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Author: Rebecca Jacob

Department of Anaesthesia

CHRISTIAN MEDICAL COLLEGE, VELLORE

Distance Learning Editor: Isobel S

Post Graduate Diploma in Family Medicine for recent MBBS Graduates

– 2013-14

Towards multicompetence in Secondary

ANAESTHESIA FOR

OBSTETRIC EMERGENCIES

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3. Anesthesia for Obstetric Emergencies

2

ACKNOWLEDGEMENTS

The distance learning course of the Integrated Post Graduate Diploma in Family

Medicine consists of 27 module booklets. The modules were prepared by CMC

faculty and doctors from mission hospitals who were trained in distance learning

methodology. The modules have been revised to meet the requirements of this

course from the distance learning materials prepared for the erstwhile Fellowship

in Secondary Hospital Medicine (under the Department of Medicine Unit 1, CMC

Vellore) and for the Post Graduate Diploma in Family Medicine (under the

Department of Distance Education, CMC Vellore). The source and authorship of

each module will be stated in the acknowledgements page.

This module – Module 3: Anaesthesia for obstetri c emergencies – was originally

written for the FSHM course by Dr. Rebecca Jacob, Department of Anaesthesia,

CMC Vellore.

The distance learning modules are the intellectual property of Christian Medical

College, Vellore. They may freely be reproduced. If they are being modified or

used as part of another course, specific permission should be obtained from the

Course Organiser at the distance learning centre, CMC.

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INSTRUCTION SHEET – Anaesthesia for obstetric emergencies (MODULE 3)

1. After you complete the module tear:

(a) Tutor marked assignment (page 33 );

(b) The module evaluation form (at the end of the module)

Send it by registered post on 27-05-13

2. Please write your name and roll number on the tutor marked assignment before

dispatching it.

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OVERVIEW

This module will help you manage the pregnant patient through emergencies that may

occur during her pregnancy such as an emergency caesarean section or management

of a retained placenta.

The module will help you understand the physiological changes in pregnancy which are

relevant to anaesthesia, take you through the various options for anaesthesia in

different situations, outline the drugs and equipment which you may need and, most

importantly, discuss safety concerns. You may find various safety issues like ‘Start an

IV line, give oxygen, check equipment and keep in left lateral position’ repeated over

and over again. This has been done deliberately to ensure that you do not over look

these safety precautions in any emergency situation.

The readings at the back of the module have been arranged to maintain the logical flow

of information. The readings required to work on each activity have been stated as part

of the instruction for each activity. Try and read all of the additional readings when you

have the time - it will improve your overall understanding of the subject.

Most of the references and reading materials are modified from ‘Update in Anaesthesia’

- a free journal publication of the World Federation of Societies of Anaesthesiologists.

Further information may be obtained from their website www.freemedicaljournals.com.

Other relevant references are mentioned at the end.

http://www.freemedicaljournals.com/



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OBJECTIVES

After completion of the module the student should be able to

1. Clinically evaluate a pregnant patient presenting for emergency surgery.2. Take the necessary precaution to safeguard the mother and the foetus.

3. Make a decision on a simple anaesthetic and be able to administer it if it is

necessary to do so.

4. Recognise and identify complications arising from the emergency and from the

anaesthetic administered and be able to ‘rescue’ the patient in this situation.

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CONTENTS

TOPIC Minutes Page nos.

Activity 3.1 Pre-anaesthetic clinical evaluation inobstetric labour 10 7

Reading Anaesthetic applications of phys changes 10 41

Pre-anaesthetic general checkup &investigations 10 42-43

Activity 3.2 Preparation of patient for anaesthesia 10 9 Reading Anaesthesia for Caesarean section: intro 10 37-40

Anaesthesia for Caesarean section 10 44-45

Activity 3.3 Choice of anaesthetic & preparation of patient for spinal anaesthetic – I 10 11

Reading Advantages, disadvantages & indications for alternative anaesthetic techniques 40 46-60

Activity 3.4 Preparation for spinal anaesthesia for pregnant patient 10 13

Reading spinal anaesthesia 97-108

Activity 3.5 Mgmt of spinal anaesthesia-inducedhypotension 10 15

Reading Management of hypotension in spinalanaesthesia 5 52-53

Activity 3.6 Post-partum haemorrhage – I 10 17 Reading Anaesthesia for obstetric haemorrhage 15 66-70

Activity 3.7Management of pregnant patient withfoetal distress 10 19

Reading General anaesthesia 10 55-60

Activity 3.8 Post partum haemorrhage - II 10 21

Reading Anesthesia for Obstetric haemorrhage 65-70Activity 3.9 Antepartum haemorrhage 10 23

Activity 3.10 Management of parturient for nonobstetric surgery 10 25

Reading Anaesthesia for non obstetric emergencies 15 71-74

Anaesthesia for patient with full stomach 15 59-65

Activity 3.11 Cardiac arrest in a parturient 10 27 Reading Cardiac arrest in pregnancy 10 74

Primary & secondary ABCD survey 10 75-76

Resuscitation of the pregnant woman 10 77-81 Activity 3.12 The (right) way to do LSCS 10 29

TUTOR MARKED ASSIGNMENT 60 33-35

Total estimated study time 350

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INSTRUCTION: Let us start with an activity to help you understand the physiological changes in pregnancy relevant to the anaesthetist and help you focus on routineexamination and laboratory investigation.Read the sections: “ Anaesthet ic appl icat ions of physiological changes in

pregnancy ” (pg.41), and “ Pre-anaesthet ic checkup and invest igat ions in pregnancy ” (pgs.42-43) before you proceed to the activity.

ACTIVITY 3.1 [TIME: 10 MIN]PRE-ANAESTHETIC CLINICAL EVALUATION &

INVESTIGATIONS IN OBSTETRIC LABOUR

A 28 year old gravida Jacinta presents for safe delivery in early labor. She hascome to hospital just after breakfast.

1. What history will you ask for?

2. What findings will you look for in clinical examination?

3. What lab investigations would be relevant?

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FEEDBACK 3.1

1. What history will you ask for?

Antepartum history

a. Booking statusb. Immunisationc. History of co-morbidities during pregnancy: high blood pressure, diabetes,

cardiac problems, bronchial asthmad. Any history of allergiese. History of previous surgery

f. Time of last meal

2. What findings will you look for in clinical examination?

a. Pallor, Pedal edemab. Pulse rate, Blood pressurec. Foetal heart rate examinationd. Auscultation: Breath Sounds, Heart Sounds

e. Airway examinationf. Spine examination

3. What lab investigations would be relevant?

Serum CreatininePCV, VDRL, Virology status if available If PIH

Blood group & type Platelet counts

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INSTRUCTION: In the next activity, you will be considering anaesthetising a patient whodoes not have foetal distress. Before you start the activity, read “Anaesthesia for caesarean sect ion : introduc t ion ” (pgs.37-40) and the second part: “Anaesthesia for caesarean section ” (pgs.44-45).

ACTIVITY 3.2 [TIME: 10 MIN]PREPARATION OF PATIENT FOR ANAESTHESIA

The second stage of Jacinta’s labor is prolonged, a diagnosis of cephalo-pelvicdisproportion (CPD) is made and the patient presents for LSCS.She is in pain, complains of a dry tongue and feeling thirsty.HR – 110/min BP 130/80 mm of Hg

1. How do you prepare the patient?

2. What do you keep ready?

3. How should you transfer the patient?

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FEEDBACK 3.2

1. How do you prepare the patient?

2. What do you keep ready?

3. How should you transfer the patient?

In left lateral position

a) Start good IV access (18G cannula) with IV crystalloid (RL or Nacl on )

b) Quick antipartum history as discussed in Feedback 1

c) Quick clinical examination

d) Reassurance

Prepare for regional anaesthetic technique – spinal anaesthesia, with all equipmentready for general anaesthesia also (in case of failure or inadequate spinal).

a. Check anaesthesia apparatusb. Oxygen mask (Hudson) – Check oxygen sourcec. Working suction apparatus (electric or mechanical for mother & baby)d. Tipping tablee. Tray with 2 working laryngoscopes, airway, stylette, endotracheal tubes of

appropriate sizes (6,6.5,7,7.5)f. Emergency drugs (ephedrine, phenylephrine, adrenaline, atropine)g. Tray for spinal anaesthesia with different size lumbar puncture needles and

the local anaesthetic agentsh. Oxytocin

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ACTIVITY 3.3 [TIME: 10 MIN]CHOICE OF ANAESTHETIC &

PREPARATION OF PATIENT FOR SPINAL ANAESTHETIC - I

The obstetrician tells you the baby is fine and that this is not an acute emergencybut Rajamani requires an LSCS due to a breech presentation.

1. What type of anaesthesia would you choose and why?

2. How would you prepare for a spinal anaesthetic?

3. What special precautions do you need to take in this patient?

INSTRUCTION: The next activity will help you learn about the choice of anaesthetic for a particular patient and precautions to be borne in mind for a spinal anaesthetic.Before beginning the activity, read “Advantages, disadvantages and indicationsfor alternative anae sthetic techniques” from pg.46 to pg.60. The section“ Regional anaesthet ic bloc kade ” is particularly relevant here. Then proceed to theactivity.

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FEEDBACK 3.3

1. What type of anaesthesia would you choose and why?

Spinal anaesthesia

Why? - Avoids the risk of difficult intubation associated with generalanaesthesia

- Pulmonary aspiration from regurgitation is avoided- Avoids poly pharmacy of drugs IV- Awake mother and early breast feeding- Less blood loss- Some post OP analgesia

2. How would you prepare for a spinal anesthetic?

3. What special precautions do you need to take in this patient?

Prepare the operation room as for a GA.Check all the equipment for resuscitation of mother and baby.Check drugs.Check suction and ‘wedge’ are available. Ensure an assistant is available.

1) Large bore IV cannula with crystalloid (Ringerlactate or normal saline, NOTdextrose) onflow

2) H2 receptor blockers (ranitidine 3mgm/kg)3) Less volume of the local anaesthetic agent4) Placement of Wedge underneath the right hip(15°)5) Prevent severe hypotension – Preloading 10ml/kg

- Use of vasopressor Oxygen by mask

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INSTRUCTION: This activity continues the learning on spinal anaesthesia. Additional information is found on pgs.97-108.

ACTIVITY 3.4 [TIME: 10 MIN]PREPARATION FOR SPINAL ANAESTHESIA FOR PREGNANT PATIENT -

II

You have not been trained to give general anaesthesia but you do know how togive a spinal. When you call up the operation theater, what will you ask thenurses to keep ready?

1. (i) (ii) (iii) (iv)

State drugs / dose / type & size of needle / position of patient

2. How would you do the procedure?

3. What special precautions do you have to take?

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FEEDBACK 3.4

1. (i) (ii) (iii) (iv)

State drugs / dose / type & size of needle / position of patient

(i) Bupivacaine 0.5% (Heavy) (ii) 1.6 to 2ml depending on the height of the patient(iii) Quincke / Whittacre needle(iv) Left Lateral position / Sitting position

2. How would you do the procedure?

3. What special precautions do you have to take?

Position patient. Apply monitor – Pulse/BP/Oximeter & check level of consciousness.Clean with sterile antiseptic solution.Drape.Identify L3-4 or L2-3 interspace and Do L.P.Ensure the flow of clear CSF.Inject drug.

Preloading 10ml/kg with crystalloid through large bore IV cannule- Small volume of the local anaesthetic agent- Placement of wedge under the right hip (15°)- O2 by mask- Keep vasopressors ready

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INSTRUCTION: Before starting on the next activity, re-read “ Management of

hypo tension in spin al anaesthesia ” (pgs.52-53).

ACTIVITY 3.5 [TIME: 10 MIN]MANAGEMENT OF SPINAL ANAESTHESIA-INDUCED HYPOTENSION

The spinal is given and the patient positioned for the LSCS. The BP drops to 80mm Hg (systolic) and the next reading in 3 min. shows 70mmHg (systolic).Patient complains of sinking feeling in chest, giddiness, nausea and vomiting.

1. What do you do?

2. What drugs can you use in this situation? How do their actions differ?

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FEEDBACK 3.5

1. What do you do?

2. What drugs can you use in this situation? How do their actions differ?

Ephedrine – Indirectly acting sympathomimeticHas more β receptor activity and preserves the uterine arterial bloodsupply

Mephentermine – 3-5 mgmPhenylephrine – Boluses of 25 – 50mcg/ kg can be administered.

Acts by increasing the mean arterial pressure

i) Intra venous fluid – Bolus of crystalloid (at least 200 ml in 5min)ii) Oxygen by mask

iii) Vasopressor – ephedrine 3 – 6 mgm repeated if necessaryiv) Check position of wedge under right buttockv) Lift uterus off IVC

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INSTRUCTION: Activity 3.6 continues the learning on complications following spinal anaesthesia. Before attempting it, read carefully “Anaesthesia for obstetr ic

haemorrhage” (pgs.66-70). Then proceed to the activity.

ACTIVITY 3.6 [TIME: 10 MIN]POST PARTUM HAEMORRHAGE - I

After the baby is delivered the obstetrician says the uterus is not contracting.The patient’s BP is 60 mmHg and HR is 120/min. The patient is cold and anxious.The obstetrician says the blood looks dark. Oximetry is 84%.

1. What is your diagnosis?

2. What would you do?

3. What are the side effects of uterotonic drugs?

4. Where are they contra-indicated?

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FEEDBACK 3.6

1. What is your diagnosis?

Atomic


3. What are the side effects of uterotonic drugs?

4. Where are they contra-indicated?

CALL FOR HELPa) Ask obstetrician to massage the uterusb) Give oxygen by mask 6.L/minc) Give Oxytocin: 10 – 20 units added to 500ml – 1000ml of Crystalloidd) Methergin – Ergot derivative for uterine contraction 0.2mgm deep IM/IVe) Carboprost – 15 methyl prostaglandins 250 μgm (0.25mgm) deep IMf) IV fluids fast crystalloids/colloids & blood.g) Take more crossmatch sample while starting another IV line with large bore

cannula. Ask for more blood.

1) Oxytocin – TachycardiaHypotension

Careful administration in cardiac patients

2) Methergin – HypertensionNausea and vomiting (can be severe)Headache

3) Carboprost – BronchoconstrictionNausea and vomiting

Methergin – Avoid in PIH, hypertension, ischaemic heart diseaseCarboprost – Contra indicated in asthmaticsProphylactic antiemetics like ondansetron 4mgm stat and Q 6 H may be required incase of use of methergin or carboprost.

Atonic post partum haemorrhage

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INSTRUCTION: The next activity deals with anaesthesia for a pregnant patient withfoetal distress. You can attempt the activity on the basis of what you have studied sofar. Read the section on “General Anaesthesia” (pgs.55-60) and also re-read pgs.37-39 before proceeding to the activity.

ACTIVITY 3.7 [TIME: 10 MIN]PREGNANT PATIENT WITH FOETAL DISTRESS

A 35 year old primigravida at 32 weeks gestation presents at 2nd stage of labor with acute foetal distress (meconium stained liquor). BP- 130/80 mm Hg Pulse -110/min RR - 30/min. Complains of severe cramping pain at 2 min interval(laboratory investigations are normal).

1. What is your choice of anaesthesia?

2. How do you proceed?

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FEEDBACK 3.7

1. What is your choice of anaesthesia?

2. How do you proceed?

General anaesthetic: There is no time to lose in foetal distress, since oxygenation of mother & foetus is paramount.

Shift to OR in left lateral position

Check anaesthetic apparatus.

Intubation tray with working laryngoscopes, appropriate size endotrachealtubes, stylettes, oropharyngeal airway

Working suction apparatus – keep running during induction with catheter tucked under patient pillow.

Tipping trolley

Emergency drugs

GET competent help & explain what is required.

RAPID SEQUENCE INDUCTION as follows:o Preoxygenation – 100% O2 – for 4 minutes (or) 4 tidal volume breathso Administration of Thiopentone 4mg/kg , Succinylcholine 1 – 1.5mg/kgo Apply cricoid pressure and do not ventilate.o Perform laryngoscopy after 60 seconds, intubate, inflate cuff. Confirm

endotracheal tube placement by auscultation of chest, chest expansion,ETCO2 trace if available.

o Release cricoid pressure (important not to do so before theconfirmation of ET tube placement).

Once the baby is delivered oxytocin may be added to the IV fluid.

Narcotics may now be given IV.

Antibiotics may also be given.

Intermediate acting muscle relaxants like vercuronium (0.1mgm/kg) or atracurium (0.5mgm/kg) may be given IV once the patient starts breathing.

Ventilation is continued with O2 + N2O inhalational agents like halothane (1%)or ether.

At the end of surgery, reverse the action of the neuromuscular agents withneostigmine (0.05mgm/kg BW and atropine 0.02mgm/kg BW).

Extubate only when patient is breathing regularly, awake and able to sustainhead lift > 5 sec, hand grip > 5 sec.

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INSTRUCTION: The following activity deals with another case of post partumhaemorrhage. Re-read the section: “Anaesthesia for obstetric haemorrhage” (pgs.65-70) before you begin the activity.

ACTIVITY 3.8 [TIME: 10 MIN]POST PARTUM HAEMORRHAGE - II

A primigravida has delivered ½ hour ago but has persistent bleeding PV. BP is 90

mmHg HR – 110/min. RR – 20/min. She has no abdominal pain.

1. What could the diagnosis be?

2. How would you anaesthetise the patient for a retained placenta?

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FEEDBACK 3.8

1. What could the diagnosis be?

a) Retained placental products in utero or birth canal tear / traumatic PPH.b) This is unlikely to be an atonic uterus as her BP is not very low even

after ½ hour.

2. How would you anaesthetise the patient for a retained placenta?

General anaesthesia with halothane is a preferred technique for manual removalof placental products. Halothane is a good uterine relaxant that is needed for complete removal of placental products. If halothane is not available thiopentoneand / or deep ether may be used.

(RAPID SEQUENCE INDUCTION WITH CRICOID PRESSURE)

After removal of retained placenta uterotonics can be administered for uterine

contraction.

N.B. Spinal anaesthesia does not relax the uterus.

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INSTRUCTION: The following activity is also a case of haemorrhage. You canattempt it on the basis of the previous readings about haemorrhages.

ACTIVITY 3.9 [TIME: 10 MIN]

ANTE PARTUM HAEMORRHAGE

34 year Rajamma G2P1L1A0, comes to the labour room with complaints of profusebleeding per vaginum for the past 1 hour. She is at 37 weeks of gestation and thebleeding is not associated with any pain.Foetal heart rate at admission was 140/min and sudden foetal bradycardia (dipsof 90 min) was noted.The obstetrician requests an emergency LSCS.

1. What is the probable diagnosis in this patient?

2. What clinical findings will be relevant and significant?

3. What information would you like to ask the obstetrician?

The patient’s BP - 70 mm Hg, HR -120/min, RR - 24/min.

4. What anaesthesia would you like to give this patient?

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FEEDBACK 3.9

1. What is the probable diagnosis in this patient?

2. What clinical findings will be relevant and significant?

3. What information would you like to ask the obstetrician?

4. What anaesthesia would you like to give this patient?

Placenta praevia, (if she has pain, consider abruptio placenta)

Pallor, pulse rate, blood pressure, fetal heart rate, amount of blood loss

Grading of placenta praevia by ultrasound guidance

General anaesthesia because of hypovolaemia and haemodynamic instability.Use ketamine as the induction agent as it helps maintain BP. Ketamine may be aproblem in foetal distress. However, in this situation the mother is consideredmore important and thiopentone could cause profound hypotension which isdifficult to reverse (this will cause further foetal hypoxia).

(Placenta praevia Gr. I & II are usually stable and spinal anaesthesia may beused in selected cases)

Before starting Anaesthesia

Place 2 wide bore IV cannula with IV crystalloid.Blood should be cross matched & transfer started as soon as possible.O2 for transfer Transfer in the left lateral position.

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INSTRUCTION: In the next two activities, you will learn how to handle the obstetric patient for non obstetric emergencies. Study the Algor i thm on pg.70 and read thesection “Anaesthesia for nonobstetric emergencies” (pgs.71-74). Also read “ Anaesthesia for a pat ient w i th ful l stom ach ” (pgs.59-65). Then you can begin the

activity below.

ACTIVITY 3.10 [TIME: 10 MIN]PARTURIENT AND NON OBSTETRIC SURGERY

A 24 year old primigravida in her II trimester has been diagnosed to have acuteappendicitis and is posted for appendicectomy.

1. What are the problems anticipated while doing this case?

2. What precautions should be taken during anaesthesia?

3. What is the anticipated risk that has to be explained to the patient about thissurgery and anaesthesia?

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FEEDBACK 3.10

1. What are the problems anticipated while doing this case?

2. What precautions should be taken during anaesthesia?

3. What is the anticipated risk that has to be explained to the patient about thissurgery and anaesthesia?

Challenges of managing two lives – that of the mother, and that of the foetus.

Mother: Physiological changes of pregnancy

Full stomach

Pulmonary aspiration

Polypharmacy of drugs – Feto placental transfer

Difficult intubation

Appendix can be pushed above the usual location Premedication with prokinetic agents

Rapid sequence induction with cricoid pressureWedge under the right hip

Avoid hypoxia, hypotensionFetal heart rate monitoring also to be done

There is a high risk of preterm labour and abortion after laparotomy.

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INSTRUCTION: Before you attempt this activity, please read the section “Cardiac arrest in pregnancy” (pg.74) and study the table “Primary & secondary ABCDsurvey” (pgs.75-76 ). Also read “ Resusci tation o f the pregnant woman” (pgs.77-81).Then proceed to the activity.

ACTIVITY 3.11 [TIME: 10 MIN]CARDIAC ARREST IN A PARTURIENT

38 year old Ramani G2P1L1 presents for a 2nd Caesarean section, the indicationbeing previous caesarean section with tenderness over the scar. The previousCaesarean section was uneventful. Her vital signs are: BP - 130/90, HR - 100/min,RR - 18/min. Spinal was given with 2 ml 0.5% Bupivacaine. BP drops to 100/70mmHg, HR - 110/min, RR –16/min.The LSCS is started, the uterus incised and BP drops to 60/? mmHg, HR -60/min,

RR - 30/min.1. What could have happened?


The ECG monitor shows a flat line. The BP is unrecordable and the patientapnoeic.

3. What has happened now? How would you proceed?

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FEEDBACK 3.11

1. What could have happened?


3. What has happened now? How would you proceed?

Tenderness in the uterine scar area may be associated with scar rupture anduterine dehiscence. In this case, however the uterus seems intact as the surgeryis started with uterine incision.

Differential diagnosis:1. High spinal with severe hypotension2. Amniotic fluid embolism

Inform the surgeon and call for help.Deliver the baby fast and lift the uterus out of the abdomen to relieve aorto-caval compression.Give IV crystalloid rapidly.Oxygen by mask at 4 L/min.Vasopressors - ephedrine.

She has had a cardio pulmonary arrest. Continue the above measures and startCPR.

A – airwayB – breathingC – circulationD – defibrillation and drugs

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INSTRUCTION: Now we will do a final exercise to go over the correct way to do anLSCS.

ACTIVITY 3.12 [TIME: 10 MIN]THE (RIGHT) WAY TO DO LSCS

In the following scenario identify the right and wrong management pattern statingwhat you would do in that situation.

Meenakshi, a 30 year old primigravida, at term, an unbooked case, presents withpainful bleeding P.V. Foetal heart - 140/min, Mothers HR - 120/min, BP - 90/60, RR- 25/min.

The patient is taken straight to the operation theater for an LSCS.

IV is started with a 20G cannula and 5% Dextrose.

Spinal anaesthesia is given at L1-2 with 3ml 0.5% hyperbaric hupivacaine.

BP drops to 60/?, HR now 140/min. She has no pain now but has started

vomiting.

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FEEDBACK 3.12

Correct management:

1. Stabilise the patient first and find cause of bleeding

History

Clinical examination

Labs: Hb, coagulation studies, blood for grouping and cross matching

O2 by mask

1 large bore IV cannula, run crystalloid fast (NOT DEXTROSE)

Check foetal heart

? Ionotropes

Explain risk to relatives- Obtain informed consent from patient.

2. Spinal should not be attempted in case of hypovolemia.GA should be given with ketamine as the induction agent

3. Hypotension is due to spinal, and vomiting is due to hypoxia and hypotension- Correct both.

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NOTES

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NOTES

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Name: Roll No:Module name:

TUTOR MARKED ASSIGNMENT (60 MINUTES)

Once you have completed the TMA, tear it out and insert it into the addressed envelopeand send it to the training centre.

Multiple Choice Questions (2 X 10 = 20 marks)

I) Indicate whether the following statements are true or false, in respect of a pregnantpatient:

The pregnant woman has

1. Increased plasma volume

2. Decreased cardiac output

3. Decreased functional residual capacity

4. Poor gastric emptying

5. The height of spinal blockade is the same in the pregnant & non pregnant

patient for a given volume of local anaesthetic.

6. Left lateral position increases aortocaval compression.

7. Sub arachnoid block produces hypotension by peripheral vasodilatation.

8. Methergine (Ergometrine) is the drug of choice in pre-eclamptic patients.

9. In a failed spinal ketamine anaesthesia is an option.

10. General anaesthesia is indicated in the case of a parturient with severe

hypotension for LSCS.

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Short Structured Answers (4 x 3 = 12 marks)

Note: If you need more space, please use extra paper.

11) Left lateral position does

1.

2.

3.

4.

12) Contraindications to spinal anaesthesia for LSCS are :

13) How would you prepare a haemorrhaging parturient for a Caesarian section?

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14) How does CPR in a parturient differ from one in a non-parturient normal adult?

Essay (8 marks)

15) 24 year old Rajeswari presents in labour to your hospital where she is diagnosedto have CPD and is posted for an LSCS.

a) What is the minimum equipment you require and the emergency drugs you shouldhave available before you start anaesthesia?

b) How will you manage her anaesthetic for an LSCS?

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READINGS

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ANAESTHESIA FOR CAESAREAN SECTION: INTRODUCTION2

Caesarean section (LSCS) is one of the commonest operations performed in the developing world

and is often carried out in difficult circumstances. As with any operation, the anaesthetist should

first think about all the problems that may occur as it is always better to be prepared for trouble

than to be taken by surprise.

The problems arise in 5 areas:

1. The patients

2. The surgery (and the surgeon!)

3. The drugs (both anaesthetic drugs and any taken by the patient)

4. Equipment

5. The anaesthetist

1. Problems with the patient

Caesarean section is often said to be a unique situation where the anaesthetist has to deal with

2 patients under the same anaesthetic. The health of the baby has to be considered as well as

that of the mother.

Risks to the mo the r : Changes in maternal physiology have been described in the earlier

section. The important changes affecting anaesthesia are:

Pregnant women are at risk of hypoxia. They are more difficult to oxygenate than non-pregnant

patients due to changes in their respiratory mechanics, and they use the oxygen more quickly

because of a higher metabolic rate. This situation can be made worse by other factors. Obesity

makes control of the airway more difficult and interstitial fluid retention may make the larynx

harder to visualize for successful intubation.

Although fluid retention is a feature of pregnancy, a more common problem is the risk of

hypovolaemia either due to obstetric complications causing significant antepartum

hemorrhage or, very commonly, prolonged labor leading to exhaustion and dehydration. This is

particularly noticeable in the hot season.The pregnant mother is at greater risk of pulmonary acid aspiration, as regurgitation of acidic

stomach contents is more likely than in non-pregnant patients. This can lead to catastrophic aspiration

pneumonitis.

The patient with hypertensive disease of pregnancy may have abnormal clotting function and

multiple other complications of this disease.

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Risks to the fetus include hypoxia and acidosis if placental blood flow is reduced. Since

maternal blood pressure is maintained at the expense (if necessary) of placental perfusion, by

the time a significant drop in maternal blood pressure has been measured the fetus has already

suffered from reduced placental perfusion. The general condition of the fetus should be

considered.

What is the state of the fetus preoperatively? How significant is any "fetal distress"? Is there an

obstetric complication, such as cord prolapse, that puts the fetus at imminent risk and requires

the quickest possible intervention? Is there more than one fetus?

Risks to mother and fetus: Both need to be protected from the "supine hypotensive syndrome"

(aorto-caval compression). This occurs when the maternal inferior vena cava and, to a lesser

extent, the aorta are compressed by the gravid uterus if the mother is allowed to lie on her back.

2. Problems with the surgery

Ask yourself the following questions: Who is the surgeon, how experienced, how long does

he/she expect to take and what incision is planned? Are blood and other intravenous fluids

available? Is there a surgical complication such as placenta praevia that could cause serious

intra-operative hemorrhage?

Does your surgeon lift the uterus right out of the abdominal cavity after delivery in order to

suture it? (Under regional anaesthesia, this is very uncomfortable and is rarely necessary.)

3. Problems with drugs

As with any patient, the pregnant woman may be taking drugs for concurrent diseases which have

to be considered, e.g. steroids, anti diabetic medication. They may also be taking drugs that can

react with anaesthetic drugs, e.g. antidepressant medication.

With all drugs, check the weight of the patient and try and weigh her if possible. Do not accept

average doses quoted in textbooks but calculate drug dosage as mg/kg. This is particularly important

in India where, fully grown women at term may only weigh 35 to 40kg.

There is a moderate reduction in psuedo-cholinesterase in pregnant women compared with

the non-pregnant population. This is more notable immediately post-partum. Although the initial

dose of suxamethonium is the same, its effect may be prolonged. If suxamethonium has not

been correctly stored it may not be fully effective.

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Ketamine causes a rise in blood pressure. It should not be given to mothers with hypertension

but is well worth considering if a mother is being resuscitated from hypovolaemia.

Ergometrine, given to encourage uterine contraction immediately after delivery, frequently

causes nausea and vomiting. It is better to use oxytocin.

Are all general anaesthesia requirements including emergency drugs available?

Drugs used for the anaesthetic may affect the fetus. Anaesthetic drugs cross the placenta and

therefore a "deep" anaesthetic will sedate the baby and risk birth apnea. Narcotics and sedatives

should not be given to the mother prior to delivery. Neuromuscular blocking agents are safe

except for flaxedil (gallamine)

4. Problems with equipment

What anaesthetic equipment is available? Is there adequate oxygen, either in cylinders or as a

functioning oxygen concentrator? Is the power supply reliable?

Does the suction work and is there a back up manually operated sucker?

Does the table tilt and is there a suitable wedge available?

Is there a range of equipment for difficult tintubation: introducers, a range of laryngoscope blades

and handles and endotracheal tubes?

Is there resuscitation equipment ready for the patient having a regional anaesthetic? What

resuscitation equipment is ready for the baby?

What sterile needles are available for spinal anaesthesia?

Is there any monitoring equipment available?

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5. Problems with the anaesthetist

Finally, you should consider how experienced you are with any particular technique and how longyou expect to take. Can you obtain the help of another anaesthetist? This is a good policy if you

are expecting a difficult intubation or other problems. Lastly, and probably as important as anything

else, do you have a trained assistant? Do they know how to do cricoid pressure correctly? Are they

strong enough to turn the patient on to her side if you get into trouble?

Having considered all the potential difficulties, make a plan for your anaesthetic.

Plan for Anaesthesia

Preoperative preparation

Preoperative induction

Postoperative care

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ANAESTHETIC APPLICATIONS OF PHYSIOLOGICAL CHANGES IN

PREGNANCY

(For more information on physiological changes in pregnancy, read “Physiological Changes

associated with Pregnancy”, Additional Readings, pgs.84-92.)

How does the pregnant woman differ with regard to physiological reserves andoxygen demand?

Although there is an increased blood volume (50%), increased left ventricular mass (50%)

increased cardiac output (40%), reduced after load, and increased minute volume (40%),

the oxygen demand is great and cardiopulmonary reserves are low. In addition, the

inferior vena cava is completely occluded at term in 90% patients, leading to 25%

reduction in cardiac output. They remain symptomless, only thanks to the patency of

collateral veins and compensatory vasoconstriction in splanchnic vessels including uterine

arteries. The reduced functional residual capacity (FRC) decreases the safe period of

apnea and physiological anemia reduces the oxygen supply. The increased tendency to

pulmonary aspiration compounds it all.

The uterus remains an intrapelvic organ until the 12 th week of gestation, when it begins to

rise out of pelvis and encroach on the peritoneal cavity. By 24 weeks, the uterus will be at

the level of the umbilicus. At 36 weeks the uterus reaches its maximal supraumblical

extent. As the uterus enlarges, it reduces the confines of the intraperitoneal space,

restricting the intestines to the upper abdomen. Likewise the intrauterine environment

gradually changes from very protective to very vulnerable. The placenta reaches its

maximum size by 36 to 38 weeks of gestation and is devoid of elastic tissue. Thus lack of

placental elastic tissues predisposes to shear forces between the placenta and uterine

wall leading to such complications as abruption placentae. The placental vasculature is

maximally dilated throughout gestation, yet extremely sensitive to catecholamine

stimulation. The uterus is therefore highly susceptible to rupture.

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PRE-ANAESTHETIC GENERAL CHECK-UP & INVESTIGATIONS1

A good history and clinical examination should take into account the normal physiological

changes in the pregnant woman.

Ante-partum work up should include:

Booking status

Immunisation

History of co-morbidities during pregnancy such as high blood pressure, diabetes,

cardiac problems, bronchial asthma

Any history of allergies

History of previous surgery

Time of last meal

In the general clinical examination, look for:

Pallor, pedal oedema

Pulse rate, blood pressure

Foetal heart rate examination

Auscultation: breath sounds, heart sounds

Airway examination

Spinal examination

The spine should be carefully examined (in case a spinal anesthetic is required later) and the

airway assessed carefully. The latter would include a check of adequate mouth opening (2

finger breadth), no loose teeth, a thyromental distance of 3 finger breadth), adequate neck

extension.

To measure the thyromental distance, have the patient sitting up with head extended and

measure the distance from the thyroid cartilage to the mentum, To check neck extension,

stabilize the patient’s shoulder, and ask him to extend his neck and not arch his back.

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The contents of the mouth, especially the size of the tongue in relation to the mouth may be

classified according to Mallampatti classification.

Class I Class II Class III Class IV

Mallampati ClassificationI : Uvula, soft palate, faucial pillars seenII : Soft palate, uvula seenIII : Soft palate seen

IV : No landmarks seen

Classes I & II are easy to intubate.

(Further reading on airway assessment – Anaesthesia for District Hospitals – Michael Dobson)

Routine Investigations in a pregnant woman include

Haemoglobin

Random blood sugar

Blood group & cross matching

VDRL

Virology status – HIV, Hep B and Hep C

Creatinine

Platelets should be checked if the patient is hypertensive, as they may be low in pregnancy

induced hypertension (PIH). (If facility is available.)

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ANAESTHESIA FOR CAESAREAN SECTION2

PREOPERATIVE PREPARATION

Visit the patient, take a history and examine her and the foetus (Portia position, HR). Consider the

state of the maternal cardiovascular system, her airway: whether or not you expect a difficult

intubation, and also the state of the fetus. Give antacid as described in the table below.

Explain the type of anaesthetic that you plan to use and what the patient can expect to happen

before, during and after surgery. Try to gain the patient's, and her family's agreement for what

you plan to do. If the patient is at high risk then this should be explained to the family concerned.

(from Update in Anaesthesia)

Elective case Ranitidine 150 mg orally the night before and 90 minutes pre op

Emergency Ranitidine 50 mg IV

immediately decision made to operate

High risk Ranitidine 150 mg orally 6 hrly

labour (e.g. Diabetic)

Premedication should not be given because it will depress the baby's respiration and consciouslevel at birth. If naloxone is available for the baby (or nalbuphine as a second-best alternative),

then pethidine may be given to the mother during labor. A good alternative to pethidine in labor is to

use inhalational analgesia, either with a 50/50 mixture of nitrous oxide and oxygen (Entonox).

ANAESTHESIA

Three anaesthetic techniques are possible:

1. Local infiltration anaesthesia with or without supplementation.

2. Regional anaesthesia

3. General anaesthesia

Before starting anaesthesia check the following:

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Antacids, suction, availability of blood, oxygen and an assistant who can do cricoid pressure.

Establish good IV access with a reliable large bore cannula and start an IV infusion of Normal

Saline or Ringer's Lactate (Hartmann's solution).

Place a wedge on the operating table, under the right side of the patient so that she is tilted tothe left by 15 to 20 degrees.

Always have at hand the drugs and equipment necessary to perform an urgent general

anaesthetic or resuscitation of mother or child. Whatever technique you start with, you may

end up giving a general anaesthetic.

Equipment and drugs that you should keep ready include:

Anaesthesia apparatus

Oxygen mask (Hudson) and reliable oxygen source

Working suction apparatus (electric or mechanical for mother and baby)

Tipping table

Tray with 2 working laryngoscopes, airway, stylette, endotracheal tubes of appropriate

sizes (6, 6.5, 7, 7.5)

Emergency drugs (ephedrine, phenylephedrine, adrenaline, atropine)

Tray for spinal anaesthesia with different size lumbar puncture needles and the local

anaesthetic agents

Oxytocin (? Methergine)

Prepare to transfer the patient on a comfortable trolley, in the left lateral position so as to

avoid supine hypotension.

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ADVANTAGES, DISADVANTAGES & INDICATIONS FOR ALTERNATIVE

ANAESTHETIC TECHNIQUES2

1. LOCAL ANAESTHETIC (LA)

The local anaesthetic infiltration is normally carried out by the surgeon. Work out the maximum safe

dose of the drug being used lignocaine 1% (10mgm/ml) 5-7mg/kg body weight (BW) with 1:200

and add adrenaline at the rate of 5 micrograms per ml of LA. This is a 1 in 200,000 solution of

adrenaline (easily made by adding 0. 1ml of adrenaline 1:1000 to each 20ml s of LA).

If available give oxygen to the mother until delivery.

Using a 100mm needle two long bands of skin are infiltrated either side of the proposed incision.

Keep the needle parallel to the skin and beware that the abdominal wall is very thin at term. Do not

stick the needle into the uterus. After incising the skin, the rectus sheath is infiltrated. In order

to anaesthetise the parietal peritoneum, a further 10mls of solution is injected under the linea alba,

once it is reached and, lastly, 5mls is injected into the loose visceral peritoneum of the uterus at the

point of the incision in the lower segment.

Reassure the patient and explain that after the local anaesthetic has been given, she will still feel

certain sensations of touch. She may experience discomfort if the head is well engaged in the pelvis.

However, the anaesthetic will prevent her feeling significant pain.

Supplementation is a problem because of the effects on the fetus and the first choice is to give

nothing until the cord is clamped, after which small doses of narcotic or sedative may be used.

Probably the safest supplementation is nitrous oxide in oxygen or as described above.

Ketamine should be used cautiously, in as low a dose as possible, and only intravenously. In

analgesic doses of 0.25mg/kg, it has little effect on the baby and, although it crosses the

placenta easily, doses up to a total of 1mg/kg can be used. Full anaesthetic doses of 2mg/kg will

sedate the baby and may cause chest wall rigidity which complicates resuscitation. If ketamine is

used then midazolam, diazepam or promethazine should be given to reduce the problems of

hallucinations on emergence. These should only be given after the cord has been cut. Ketamine

also causes contraction of the uterus and should probably be avoided in cases of significant fetal

distress. Atropine 0.5 mgm may be needed with ketamine because of excess salivary

secretions.

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DO NOT use Ketamine in case of heart disease, severe foetal distress, hypertension, raised ICP or

IOP or with a h/o psychiatric illness or seizures.

Other points with local and regional anaesthesia:

Atropine is also useful in combating the discomfort and nausea that some patients feel on surgical

traction on the peritoneum.

If ergometrine is used to contract the uterus after delivery it will cause vomiting which may be

awkward to manage in the supine position during surgery. If it is the only drug available give it very

slowly intravenously, preferably with the infusion running. Oxytocin is better, either in a drip at 10-

20 units in 1000mls running at 2 to 3mls/minute or a 5 to 10 units IV bolus slowly intravenously.

Ondansetron 4 to 8 mgm may be given to prevent vomiting. Odansetron is cheap and freely

available

N.B. If these drugs are mistakenly given prior to delivery, constriction of the uterus can be

a catastrophe for the baby. There is no need to draw up the oxytocin until it is needed

after delivery of the baby and on checking with the surgeon.

Advantages and disadvantages of local anaesthesia infiltration

Advantages:

o It is safe, especially for mothers in poor condition and those who are hypotensive.

o There is a reduction in bleeding because of the adrenaline.

o It is a suitable technique for the single operator/anaesthetist although any supplementation

is best avoided.

o It is inexpensive, requiring minimal resources.

Disadvantages:

o It is not always a perfect technique and the mother may experience considerable

discomfort.

o It takes time to establish and gives less surgical exposure.

o It requires experience and patience on the part of the surgeon.

Indication: It is probably most suitable when a reasonably experienced surgeon has limited

anaesthesia backup.

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2. REGIONAL ANAESTHETIC BLOCKADE (Additional reading: Spinal anaesthesia – a

practical guide pgs.100-111)

Either epidural (extradural) or spinal (subarachnoid) blocks may be used. A combined spinal +

epidural technique has the advantages of a dense subarachnoid block, with the potential for

topping up the anaesthetic via the epidural if necessary. In addition the epidural may be used for

postoperative analgesia. This combined technique is rarely done in the developing world and will

not be further discussed. Epidurals are technically more difficult to perform than spinal

anaesthesia and require more specialised equipment, which is often not available in the

developing world. There are significant and potentially fatal complications and they require

experienced anaesthetists and midwives for their safe use.

Advantages:

The patient is awake and therefore her airway is safe.

The baby is not sedated and is usually born in good condition providing hypotension is avoided.

If the baby is born with a low Apgar score the anaesthetist is free to resuscitate the baby (unless he

is also the surgeon!).

With a little experience the technique is as quick as giving a general anaesthetic and provides good

operating condit ions with some reduction in surgical haemorrhage.

It has the advantage of giving good pain relief for several hours after surgery and is

straightforward to learn and teach.

It is inexpensive and appropriate for most cases.

Contraindications:

It should not be used in cases such as:

unresuscitated preoperative hypovolaemia

dire foetal distress

bleeding disorder

sepsis at the site of injection

allergy to local anaesthetic

patients suspected of having raised intracranial pressure

patients with hypertensive disease of pregnancy (should have clotting function checked

before spinal anaesthesia)

Preparation before spinal anaesthesia

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Explain the technique and its advantages to the patient. There are widely varying views on

spinal anaesthesia among different patient populations (and also between surgeons!). Ensure that

the patient understands that pain sensation will be abolished but she should expect some pulling

and pressure sensation during surgery which may be unpleasant but will be short-lived.

The preparations described above are necessary, i.e. antacids, IV access, wedge, suction,

assistant who can give cricoid pressure, full GA and resuscitation drugs and equipment for

mother and child, oxygen until the baby is delivered, and blood for transfusion. A sterile surface

should be prepared for the procedure with all equipment for spinal anaesthesia available.

The drug required is: Bupivicaine 0.5% (heavy) – 1.6 – 2 ml depending on the height of the

patient.

The needle required is: Quincke / Whittacre needle.

Inform nurse regarding positioning of the patient in the left lateral or sitting position.

Choice of local anaesthetic - drugs, ampoules and doses

You will have to use whatever drugs are available. A hyperbaric agent (local anaesthetic mixed

with glucose) is most useful as it has a quick and predictable onset and usually produces a

dense block. If you want to keep the level low and do a saddle block you will need the heavy

solution. Solutions injected into the subarachnoid (or extradural) space should always be

preservative free and taken from a single dose vial not a multi dose container. Where possible

the ampoules should be sterile to make drawing up the solution easier. This can be achieved by

buying sterile wrapped ampoules or by autoclaving glass ampoules of local anaesthetic. Never soak ampoules in sterilising solutions. If the ampoules are not sterile on the outside, draw up the

drug carefully ensuring complete sterility.

Bupivacaine lasts longer and should be used if prolonged surgery is expected e.g. Caesarean

section followed by hysterectomy.

Engorgement of epidural veins in pregnancy reduces the subarachnoid space and hence a given

volume of local anaesthetic will have a wider spread in the pregnant than in the non-pregnant

female. The height of the block also depends on the size of the woman. Be aware of the small

stature of Asian women. At the same time, ethnic groups who are tall will require significantly

higher volumes.

In the authors' experience, the following regimes have been effective, giving a block to T5 or T6.

1.2 to 1.4mls of heavy 5% Lignocaine in Nepali women (depending on height)

2.0 to 2.5mls of heavy 0.5% Bupivacaine in Caucasian women.

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N.B. At CMC we normally give 0.5% Bupivacaine 1.6 to 2 ml. (as a rule of thumb the dose of

0.5% bupivacaine is double that of 5% lignocaine (0.8 to 1 ml lignocaine = 1.6 to 2 ml

bupivacaine 0.5%)

(See Additional Readings: Local Anaesthetics for Spinal Anaesthesia, pg.106.)

If the height of this or any block proves inadequate then it may be supplemented with an opioid

after delivery. Ketamine, always starting with a low analgesic dose or inhalational analgesia with

air / Trilene or nitrous oxide and oxygen are alternatives. Great care must be taken to avoid loss

of consciousness and inadequate protection of the airway.

Choice of needle

One problem with spinals that has limited their use in the past is the occurrence of significant

headache for 2 or 3 days following the procedure. This is due to leakage of CSF through thehole made by the needle and it is more common in pregnant women because the raised CSF

pressure, due to dilated epidural veins, causes a bigger leak. The rate of post dural puncture

headache is related to the size and design of the needle. Use the smallest gauge needle you

have available, preferably 25 or even 26 gauge. If you have to use a 22 gauge spinal needle

then you may find that the incidence of headache is unacceptable. When placing the spinal

needle try to align the bevel of the needle along the body. This parts the fibres of the dura rather

than cutting them, and reduces the incidence of headache.

In recent years a new design of needle has been used which has an atraumatic "pencil-point"

tip, instead of the standard cutting needle design. These reduce the rate of post puncture

headache to less than 1% and are worth considering. (The whitacre pencil point HP needle is

now available in India.)

Some spinal needles can be reused, providing they are properly sterilised after each use. The

best way of doing this is to use needles with metal hubs that can be re-autoclaved. Some

plastic hubs can also be autoclaved.

Technique of spinal anaesthesia

• Measure a baseline blood pressure.

• Pre-load the mother with one litre of normal saline or Ringer's lactate solution

(Hartmann's) NOT DEXTROSE prior to performing the block.

• Have a vasopressor drawn up and diluted, ready for injection.

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• The block can be performed either with the mother sitting up with her feet on a stool and

her body bent forward over a pillow on her lap; or lying on her side with the spine well

flexed. The injection should be at the level L2/3 or L3/4.

• The injection should be performed with full sterile precautions. The skin must be prepared

with an alcoholic or iodine based skin preparation. The anaesthetist should be wearing

sterile gloves and a face mask. A sterile drape should be placed over the patient if they

are in the lateral position.

• Explain what will happen to the patient as this will help them to stay still.

• Inject local anaesthetic to the skin.

While waiting for the local anaesthetic to take effect, draw up the correct dose of the spinal

injection which you plan to use and leave it ready beside you on the sterile surface. Ensure that

your drawing up needle touches only the inside of the ampoule that you are using. Check the

name, concentration and expiry date of the spinal anaesthetic twice. Almost all serious

neurological complications of spinal blocks have been due to the wrong drug being injected into

the subarachnoid space due to lack of vigilance. Record the batch number and date of expiry of

the drug on your anaesthetic chart.

• For the mid-line approach, place a spinal needle introducer between the lumbar spines

to a depth of 2 or 3 cms until it is firmly held by the interspinous ligament. If the proper

introducer is not available, a size 19 gauge hypodermic needle can be used. Insert the spinal

needle size 25 to 26G is preferable with the stillette through the introducer and advancesteadily and carefully feeling for the slight extra resistance of the ligamentum flavum followed by the

easing of resistance which occurs when the subarachnoid space is entered. This normally lies

at a depth of about 4-6cms and you can check your progress from time to time by withdrawing

the stillette and seeing if CSF flows back.

• On entering the subarachnoid space, hold the the hub of the needle firmly in place by resting

the back of the left hand (for a right handed person) on the patient's back and holding the hub

between thumb and forefinger. Carefully attach the syringe of spinal anaesthetic solution and

withdraw gently on the plunger. CSF should flow back steadily and can be seen as "oily" streaks if a heavy solution isused. If all is well, steadily inject the anaesthetic solution and withdraw the

needle and introducer. Apply a small dressing or sticking plaster over the puncture wound.

(See Additional Readings, pgs.104-106 for further details regarding physiology of spinal

anaesthesia.)

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An alternative approach in difficult cases, or by choice, is the paramedian approach. In this case

the local anaesthetic is infiltrated one finger's breadth lateral to the L3 or L4 spinous process.

Place the introducer at right angles to the skin, followed by the spinal needle which is advanced

straight in until it hits the lamina of the vertebra. Then angle it slightly medially and cephalad

(towards the head) and "walk" it off the lamina aiming for the gap between it and the lamina

above in the midline. Advance the needle until CSF is found then proceed to inject the local

anaesthetic as described above.

Difficulties: If the patient experiences pain, the introducer is probably not in the midline but is

contacting the periosteum of an adjacent vertebra or in the muscle on one or other side of the

ligament. The patient can tell you which side you are on, which will help you to redirect your

needle. Withdraw the introducer and reposition it - it should be held firmly by the interspinous

ligament. If it moves around freely, it is probably lying to one side of the midline and is not in the

ligament. If the subarachnoid space is not found, try re-positioning the patient and get your

assistant to help flex the patient's back more (that's why they need to be strong!). Alternatively

try a different space or the paramedian approach. If blood flows back when you remove the

stillette it is probably due to minimal trauma to the small veins in the epidural space. Wait until

clear CSF flows and then inject the spinal solution. If it doesn't clear ,reposition the needle slightly

further in or try flushing with sterile saline. If blood continues to flow, you must NOT inject the spinal

anaesthetic but withdraw the needle and try again in a different space.

After injecting the local anaesthetic, lie the patient down on her right side for 2 or 3 mins, then place

her tilted to the left on a wedge ready for surgery. This helps ensure that the block spreads to both

sides of the abdomen.

N.B. This turning may be avoided if the spinal is given with the patient in the right lateral

position.

The height of the block can be assessed by testing for loss of temperature sensation using ice or

cotton wool soaked with ether. Alternatively test gently for loss of pinprick sensation using a sterile

needle. The block should be above the umbilicus and preferably towards the xyphisternum. The

block works almost immediately, and you can allow the surgeon to proceed after 5 minutes.

MANAGEMENT OF HYPOTENSION IN SPINAL ANAESTHESIA

Sympathetic blockade occurs due to the action of the local anaesthetic on the sympathetic

nerves which are easily blocked, often for several segments higher than the dermatomal action.

This leads to vasodilatation in the lower limbs, venous pooling and hence hypotension, Hypotension

often presents with hypoxia, nausea and vomiting. Thus nearly all patients will have some fall in

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systolic BP (which is one of the signs of a successful block) and, furthermore, placental blood

flow is reduced before maternal systolic BP falls. It is important to take preventative measures to

minimise the fall in BP and to act quickly to treat it.

Preload the patient with IV fluid as described and measure the BP before the block and at least

5 minute intervals thereafter.

Make sure the left sided tilt is adequate.

If the systolic BP falls more than 20mmHg from the baseline then speed up the drip and give

oxygen. If this does not reverse the hypotension then give a dose of vasoconstrictor (ephiedine

3mgm). These should be diluted and given in small bolus doses every few minutes until the

hypotension is treated. Do not tilt the patient head down as this will potentially increase the height of

the block. A feeling of nausea is often the first symptom of hypotension.

In a number of patients, the block will be high enough to cover the mid-thoracic sympathetic

outflow to the heart (T4-T6) even when the correct dose is used. This prevents a compensatory

increase in heart rate and may even cause a significant bradycardia. Severe falls in BP are

sometimes seen and should be treated immediately. Give atropine (0.5mg) for bradycardia.

Recommended vasopressors

Drug Action Initial/Follow-up dose

Ephedrine (best drug) Vasoconstrictor andincreases heart rate with

some inotropic action

Phenylephrine Vasoconstrictor only 200/100 micrograms(reflex Bradycardia)

Adrenaline (use only if other Vasoconstrictor and 0.5-1ml of 1:10,000 -drugs are unavailable) increases heart rate ++ make by diluting 1ml of l:1000to 10mls and inotropic action total with saline

(Further information on this is available in the Additional Readings: “Pharmacology of Vasoprocessors and Inotropes”, pgs.112-117.)

CLINICAL CASE STUDY- USE OF VASOPRESSORS3

Lower segment Caesarean section (LSCS) under spinal anaesthesia

A patient is scheduled for LSCS under sp ina l anaesthesia. An iv infusion is set up and

1000 mls of Hartmann’s Ringer lactate is run in whilst the spinal is performed. The patient is

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placed supine with a 15-degree left-lateral tilt to minimise aortocaval compression (i.e. pressure

from the uterus on the inferior vena cava reducing venous return to the heart).

Despite good positioning and iv fluids, hypotension is very likely at this stage because of

vasodilation due to the spinal. The patient should be given ephedrine in boluses of 3-6mg, which

may need to be repeated several times. Alternatively, 30-60mg of ephedrine can be added to the

intravenous infusion, and the rate titrated according to the BP. The SBP should be

maintained above 100mmHg. (A hazard of adding ephedrine to the infusion is that the

anaesthetist may (N.B.) forget to reduce the rate of infusion when the BP has returned to

normal, and the patient may become dangerously hypertensive.)

Once the baby has been delivered aortocaval compression is no longer a problem, and

further ephedrine is not usually required. If hypotension persists, ensure that hypovolaemia

(check blood loss) is not the cause. Intravenous fluids should be given to restore blood volume,

rather than vasopressors. Ephedrine is the best vasopressor for LSCS because it has fewest

effects on placental blood supply. If ephedrine is not available another vasopressor should

be used. Alternatively small doses of adrenaline (20-50mcg) can be given, in a dilute

preparation.

High spinal blocks: If the block is high then the patient may complain of tingling or even

weakness of the upper limbs. Even though some of the intercostal muscles will be paralysed, the

diaphragm is unaffected and these patients should be managed with a slight head-up tilt (to

prevent a hyperbaric agent spreading higher), crystalloid vasoconstrictor oxygen andreassurance. With these high blocks many patients will complain of an unpleasant feeling of not

being able to take a full breath, however, they will be able to speak normally. If the patient gets

difficulty in speaking with associated tingling in the arms this is indicative of a very high block which is

beginning to affect the diaphragm. Immediate resuscitation along the normal lines of Airway,

Breathing, Circulation; together with rapid intravenous fluids and large doses of

vasoconstrictors will rescue the situation. This is one reason why full resuscitation drugs,

equipment and skilled personnel must always be immediately available whenever a regional

anaesthetic is given. Midazolam 1-2 mgm can be used for retrograde amnesia. Remember thata long acting muscle relaxant will not be required.

Nausea: Apart from hypotension, this may be caused by traction on the peritoneum in which case a

small dose of atropine may be helpful. Ergometrine (methergine) will also cause nausea and is

best avoided in the awake patient.

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Sedation: As previously discussed, none should be given prior to delivery, unless it is known that

the baby is dead.

Caudal anaesthesia: For completeness it should be mentioned that epidural anaesthesia via the

sacral hiatus has been used to establish regional anaesthesia for LSCS. However, it gives an

unpredictable spread of anaesthesia and slower onset, and is not recommended.

(Additional Readings: Factors affecting the spread of Local Anaesthetic solution, pgs.109-111;

Practical problems with Spinal Anaesthesia, pg.111-112)

3. GENERAL ANAESTHESIA (GA)

General anaesthesia will be necessary if there are contraindications to spinal anaesthesia or if

you cannot encourage either the mother or the surgeon to do the operation with the patient

awake.

Indications for general anaesthesia for LSCS

Dire foetal distress

Acute maternal hypovolemia

Significant coagulopathy

Sepsis at site of spinal

Inadequate regional anaesthesia

Maternal refusal of regional anaesthesia

Risks of general anaesthesia

The main risk associated with general anaesthesia is that of airway control. There is a significantrisk of aspiration of stomach contents and only 30mls of acid aspiration can cause a fatal acid

pneumonitis (Mendelson's syndrome). ALL PREGNANT PATIENTS SHOULD BE

CONSIDERED ‘FULL STOMACH’ and in danger of acid aspiration. (See the following

reading which deals with this topic in detail.)

Preparation for General Anaesthesia

General precautions previously mentioned must be observed.

Ensure good IV access, antacids and left lateral tilt.

If it is an emergency with a significant risk of a full stomach then it is safest to pass a large

bore nasogastric tube to drain the stomach. Remove the tube before inducinganaesthesia.

Check that the suction is working.

Always use a rapid sequence induction with pre-oxygenation and drugs given by bolus injection

according to the patient’s weight. Cricoid pressure is maintained until the anaesthetist is satisfied

that the airway is secure and both lungs are being ventilated.

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If a draw-over circuit is being used then preoxygenate the patient from a reservoir bag filled

from an oxygen cylinder or an oxygen concentrator.

Monitor closely throughout. Measure the blood pressure at least every 5 minutes and the pulse

continuously.

(See Additional Readings: pgs.96-98 regarding monitoring during General Anaesthesia.)

Common Problems Intubation is often more difficult than in the non-pregnant patient, especially

if the mother is obese. Since oxygen consumption is high you cannot afford to take too long.

Assess the difficulty of intubation beforehand and if you anticipate difficulties consider whether

spinal anaesthesia should be your first choice or try and get an experienced colleague to help

you.

Ensure there is a reliable, trained assistant. Prepare your different introducers, laryngoscopes

and Magills forceps.

If there is not enough room for the laryngoscope handle because of a short neck or large breasts

(or both!), try a child's laryngoscope handle with an adult blade or when using an adult handle,

take off the handle, insert the blade and then re-attach the handle afterwards. A short handle is

now available and is well worth having handy.

During maintenance of anaesthesia most anaesthetists continue the muscle relaxation

using either a non-depolarising muscle relaxant or sometimes intermittent suxamethonium.

This allows a light inhalational anaesthetic to be given. If you are using N2O/O2, give 50% N2O only

and add 10% halothane or 1 -1.5% ether if you are using air/ oxygen give 50% oxygen if possible

together with twice the percentage of volatile agent recommended above.

If you are not using a relaxant technique after intubation then ether breathed spontaneously has

a good safety record provided that the baby is delivered quickly. Light ether anaesthesia

does not cause too much relaxation of the uterus.

After the baby is born you can revert to a standard anaesthetic and give narcotic analgesics.

Avoid high concentrations of halothane (ideally no more than 10%) as it can increase the blood

loss during surgery by relaxing the uterus.

Recovery Because of the risk of aspiration, it is preferable to extubate the mother on her side,

when she is awake and in full control of her airway.

Particular complications: A failed intubation plan must be available and discussed regularly.

Your colleagues should know what to do and it should be printed on a card and attached to the

anaesthetic machine. The priorities are:

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• Ensure full oxygenation of the mother at all times.

• Give only the initial dose of suxamethonium and do not attempt intubation too many times.

• If you have no success with introducers and other intubation aids then accept that you will

not be able to intubate and ventilate the mother with a face mask until spontaneous

respiration returns.

• Maintain correct cricoid pressure at all times.

• The safest thing to do is usually to allow the patient to wake up and perform the operation

under a spinal anaesthetic.

If the airway is easy to maintain and the operation is urgent it may be necessary to consider

proceeding under general anaesthesia (ether 4-6% or halothane 1-1.5%) without an

endotracheal tube. An alternative is ketamine though this does not provide such good relaxation

for the surgeon. In all cases maintain cricoid pressure until the operation is finished and the

patient can be turned into the left lateral and head down position.

Remember that the baby will be sedated, and will probably require resuscitation, so get help.

Whatever happens, do not let your patient die or suffer brain damage just because you cannot

intubate. If the airway is completely obstructed and mask ventilation impossible, do an immediate

cricothyroidotomy with a large IV cannula. This should be converted to a formal tracheostomy or

the mother allowed to wake up and regain control of her own airway.

Acid aspiration: If the patient vomits or regurgitates during induction of anaesthesia, the airway

should be suctioned and the patient immediately placed in the left lateral head down position to

prevent aspiration. Depending on the situation the patient may then be intubated rapidly or

woken up.

Vomiting and regurgitation can also occur during recovery and it is imperative that patients are

not left on their backs during this phase. Solid food causes immediate airway obstruction

resulting in hypoxia, whilst liquid gastric contents cause an acid pneumonitis (inflammation of

lung tissue). If aspiration occurs at induction, then intubate the patient and clear the airways with

suction. Consider bronchoscopy (if available) to remove solid food. Lavage of the airways is

ineffective and not recommended. Ensure adequate oxygenation using added oxygen if available.

The diagnosis can usually be confirmed by listening with a stethoscope to the mid zone of the lungs

at the tips of the scapulae 30 minutes after the event. Fine crepitations heard in this area are an

early sign of aspiration pneumonia and, if the aspiration is significant, signs of hypoxia will

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develop. Within a few hours the chest X-ray will show signs of aspiration pneumonitis. The

patient will require supportive treatment with oxygen, chest physiotherapy, nebulised

bronchodilator and observation, particularly of respiration, for 24 - 48 hours. If respiratory function

deteriorates then aggressive supportive treatment will be needed including high flow oxygen and,

if necessary, intubation and ventilation. When there is no obvious deterioration, if the patient is

well after 6 hours, clinically significant aspiration is most unlikely to have occurred.

In making the diagnosis, consider other causes of hypoxia and respiratory failure in late

pregnancy, e.g. pulmonary oedema (fluid overload, cardiac failure, pre eclampsia/ eclampsia),

amniotic fluid embolism and pneumonia.

Some authorities recommend giving steroids immediately but opinion is divided on whether or

not to give antibiotics since acid pneumonitis is initially a sterile condition without bacterial

infection. Give broad spectrum antibiotics if solid matter has been inhaled or if signs of a

secondary bacterial pneumonia develop after a day or two.

Intra-operative haemorrhage Good surgical technique should prevent the need for

transfusion in most patients unless they are previously significantly anaemic and/or have

been haemorrhaging in labour. Catastrophic haemorrhage can occur with certain placental problems

(placenta praevia or abruption) or abnormalities (placenta accretia). All patients presenting for

LSCS should be cross matched for 1 unit of blood before theatre. If haemorrhage is anticipated more

blood should be cross matched.

Special circumstances - the operator anaesthetist.

At some small hospitals the surgeon conducts the anaesthetic as well as performs the operation.

This is a difficult situation, but is commonplace in many parts of the world. Techniques of

anaesthesia used in this situation include local infiltration, spinal anaesthesia, epidural

anaesthesia and ketamine. Whatever method of anaesthesia is used, expertise will develop with

experience. A trained assistant must care for the patient throughout the operation to look after the

airway and monitor the patient's vital signs. Regional techniques, during which the patient

remains awake, are probably safer.

Summary

In most circumstances LSCS is a straightforward common operation, which requires little

alteration to our normal anaesthetic practice. Preparation should be thorough and problems

anticipated before they occur. Plans should be prepared for emergencies such as a failed

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intubation or unexpected severe haemorrhage. Both general anaesthesia and regional

anaesthesia may be associated with unnecessary mortality if they are not carried out carefully. In

all cases keep reminding yourself of the 4 cornerstones which are easily forgotten: suction,

cricoid pressure, left lateral tilt and close observation.

A Techniq ue for General Anaesthesi a in Elective Caesarean Section

1. Intravenous administration of an H2-receptor antagonist and/or metoclopramide 30

to 60 minutes pre-induction.

2. Administer 500 ml to 1000 ml of a non-glucose containing balanced salt solution via

a large bore IV catheter.

3. Maintain left uterine displacement.

4. Apply monitors (ECG, pulse oximeter, blood pressure monitor, peripheral nervestimulator, precordial stethoscope.

5. Preoxygenate with 100% oxygen via tight fitting face mask (3 to 5 minutes).

6. Perform a rapid sequence intravenous induction complete with cricoid pressure.

(See pg.65) Administer thiopental 4 mg/kg followed immediately by succinylcholine

1.0 to 1.5 mg/kg. Perform laryngoscopy and intubation (6.0 to 7.0 mm endotracheal

tube) when adequate muscle relaxation has been achieved (approximately 45 to 60

seconds). Have a plan on how to handle an unexpected difficult intubation.

7. Ensure proper placement of endotracheal tube and then release cricoid pressure.8. Administer nitrous oxide in 30% to 50% concentration. Dial in a low concentration

of a potent inhalation agent (e.g. halothane 0.5%, Isoflurane 0.6% to 0.75%, or

enflurane 1.0%). Avoid hyperventilation as hypocarbia leads to uterine artery

vasoconstriction and decreased utero-placental blood flow, jeopardizing the foetus'

well-being.

9. After delivery deepen anaesthesia with increased nitrous oxide (upto to 70%),

narcotics, barbiturates, benzodiazepines, or propofol with or without the

continuation of 0.5 MAC potent inhalation agent.

10. Administer muscle relaxant as necessary (small doses of vecuronium or

atracurium).

11. Reverse the action of the neuromuscular agents with nestigmine (0.05 mg/kg BW

and 0.02 mgm/kg BW).

12. Extubate when patient is breathing regularly, awake, can maintain her airway and

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can maintain a sustained head lift.

13. If she is drowsy, recover her in the left lateral ‘recovery’ position .

ANAESTHESIA FOR THE PATIENT WITH A FULL STOMACH6

One of the major risks posed by patients who have not been prepared for theatre is that they

may not have an empty stomach. When consciousness is lost (as during induction of general

anaesthesia) the patient with stomach contents may regurgitate gastric material via the

oesophagus which may be aspirated into the lungs causing a severe pneumonitis (inflammation

of the lungs) usually called "aspiration pneumonitis". This is especially severe, and often fatal, if

the gastric contents are markedly acidic (pH < 2.5). As little as 30 mls will cause a severe

reaction. When solid foodstuffs are aspirated, complete obstruction of the airway may occur.

Why do people regurgitate? Normally the specialized junction between the oesophagus and

the stomach, the oesphagogastric junction (which may also be called the cardia) acts as a

sphincter to prevent material returning to the oesophagus after entering the stomach. When the

conscious level is depressed this junction works less efficiently and if the pressure within the

stomach (the intragastric pressure) is greater than the closing pressure of the sphincter then

regurgitation will occur. Note that regurgitation is different from vomiting. Vomiting is an active

process and involves contraction of the abdominal muscles; regurgitation is passive involving

smooth muscles only.

Normally patients are fasted for 2 hours after clear fluids and 6 hours following a meal before they are

anaesthetised. This is to reduce the chance of any residual food remaining within the stomach.

However these periods of fasting may not always guarantee an empty stomach. Patients who have

been traumatised, or are suffering from intra-abdominal pathology, or who have had opioid drugs or

are in labour do not empty their stomachs efficiently and should always be treated as if they have a

full stomach.

The risk of regurgitation is greater if the intragastric pressure is increased by the presence of food

or liquid within the stomach, the lithotomy position (legs up with patient on their back), obesity or

an intra-abdominal swelling such as pregnancy after 24 weeks or ovarian masses.

Pregnancy further increases the risk of regurgitation as hormonal changes decrease the

efficiency of the oesophagogastric junction. A hiatus hernia may render the oesophagogastric

junction ineffective; patients with this condition will usually give a history of 'heartburn' or indigestion

when they lie down.

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The Anaesthetic Approach to the Patient with a Full Stomach

Identify the patient at risk. Any patient who falls into any of the categories above should be treated

as having a 'full stomach'.

Consider the operation planned and its urgency. If the operation can be delayed to allow the

stomach to empty then this approach should be adopted. However the patient's life should not be

put at risk by delaying urgent procedures. It should be remembered that some ill patients may be

unable to empty their stomachs.

If possible reduce the volume, pressure and acidity of the stomach contents. Patients with a

stomach full of liquid, such as those with bowel obstruction or who are drunk should have a

large nasogastric tube passed prior to general anaesthesia.

Often the patients will vomit during attempts at passing of a nasogatric tube. Remember that

even after passing the tube, the stomach is unlikely to be completely empty as nasogastric tubes are

inefficient for removing liquids and useless for solids.

As discussed earlier, certain elective patients, such as obese patients, those with diabetes mellitus,

those with ascites, and pregnant females in the third trimester, are at risk of acid aspiration despite

being adequately fasted. This group of patients is best treated by decreasing the acidity and

volume of gastric fluids by the use of ranitidine or cimetidine given 1 to 2 hours preoperatively.

Unfortunately this is not adequate for emergencies who should also be given 30mls of sodium citrate

immediately before induction of anaesthesia. Such techniques will raise the pH of the gastric fluid

and make the consequences of aspiration less serious. Unfortunately not all anaesthetists

have access to these drugs but most pharmacies can make up sodium citrate. Some patients,

however, tend to vomit after the sodium citrate.

Consider the Best Form of Anaesthesia

Due to the risks associated with general anaesthesia the use of a local anaesthetic technique

should be considered. This will avoid depressing the conscious level. Beware however of using

deep sedation in combination with local anaesthesia. Some anaesthetists believe that

ketamine protects the airway by preserving laryngeal reflexes - this is not true.

If general anaesthesia is required in a patient at risk of having a full stomach the airway should be

protected by a cuffed endotracheal tube. (Under the age of 10 an uncuffed endotracheal tube

should be used.) The safest technique for introducing an endotracheal tube in this situation is

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called a rapid sequence induction (RSI or crash induction) using preoxygenation and cricoid

pressure.

Preoxygenation. Under normal circumstances the lungs contain a mixture of oxygen, nitrogen

and carbon dioxide. At the end of expiration the volume of gas left in the lung (about 2 litres) is

called the Functional Residual Capacity (FRC). This contains the oxygen reserve on which the

patient depends when they are not breathing. Most of the gas in the lung is nitrogen which can be

replaced with oxygen thereby increasing the oxygen reserve. The technique of replacing the nitrogen

contained in the FRC with oxygen is called preoxygenation or de-nitrogenation. After 3

minutes of breathing 100% oxygen most of the nitrogen has been replaced by oxygen.

Cricoid pressure. The cricoid is a ring shaped cartilage situated between the first tracheal ring

and the thyroid cartilage. When firm backward pressure is applied to it, the oesophagus is occluded

preventing any regurgitated gastric fluid from entering the pharynx. It is completely reliable providedthe pressure is put on the correct area. The backward pressure should be firm; if the equivalent

pressure is applied to the bridge of the nose it feels uncomfortable.

Technique of Rapid Sequence Induction

1. Prepare your equipment and drugs - where possible this should include all the apparatus listed

in the table below. Check all the equipment carefully before starting and ensure that everything is to

hand.

Table - Equipment required for a ‘crash’ induction.

Tilting trolley or operating table

Suction apparatus and tubing

Anaesthetic machine, source of oxygen, anaesthetic circuit and facemask

2 appropriately sized working laryngoscopes

Correct size of endotracheal tube and one a size smaller

Endotracheal tube introducer, cuff syringe and connections to circuit

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Range of oral airways

Anaesthesia drugs - induction agent, atropine and suxamethonium

A trained assistant

2. Consider whether a nasogastric tube should be passed.

3. Assess how difficult endotracheal intubation is likely to be. If you expect difficulties think

again whether local anaesthetic could be used or consider an awake intubation?

4. Insert an intravenous cannula and demonstrate the position for cricoid pressure to your

assistant.

5. Preoxygenate the patient. Using a Magill or other anaesthetic breathing circuit, turn the oxygen

to 6 to 8 litres/minute and apply the facemask to the patient. Ensure that there is a good seal

between the mask and the patient's face. Ask the patient to breathe oxygen for three minutes. Do

not allow the patient to breathe even a single breath of air during this phase or else the

preoxygenation will have to be repeated. This is due to the volume of nitrogen that is contained in a

single breath of air.

6. Estimate the dose of induction agent which the patient will need (e.g. thiopentone 5mg/kg) less

in the pregnant patient and give this intravenously, immediately followed by suxamethonium

1.5mg/kg. As soon as consciousness is lost ask your assistant to apply cricoid pressure.

7. Keep the facemask in place but do not ventilate the patient manually as some of the oxygen may

enter the stomach increasing the intragastric pressure. As soon as the suxamethonium is effective

intubate the patient, inflate the endotracheal tube cuff and check the position of the tube by listening

to the lungs with a stethoscope. If you have endtidal carbon-di-oxide it will help confirm placement of

the tube.

Note: if intubation is delayed for any reason, or the patient's colour deteriorates, manual inflation of

the lungs should be immediately carried out with cricoid pressure in place.

8. When you are satisfied that the tube is placed correctly, fix it and then instruct your assistant

to release the cricoid pressure.

9. Proceed with the anaesthetic and surgery as planned. At the end of the surgery turn the patienton to their side and do not remove the endotracheal tube until the patient is fully awake and capable

of protecting their own airway.

Difficulties with the Technique

1. Intubation is unexpectedly difficult. Ensure that the cricoid pressure is not pushing the larynx to

one side. If it is, move the larynx and cricoid cartilage by moving your assistant's hand to

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the correct position. Do not release cricoid pressure. If the suxamethonium needs to be repeated

remember to give atropine before the second dose to avoid bradycardia, and ventilate the patient

gently to prevent hypoxia. Maintain cricoid pressure at all times. If intubation proves impossible

then carry on as described under failed intubation.

2. No oxygen. Obviously no preoxygenation can take place but it is sti ll possible to use cricoid

pressure as discussed above. In this situation the patient will need to be gently ventilated with air

to prevent hypoxia after apnoea develops.

3. No suxamethonium. The best option here is to induce the patient in a head down position on the left

side using an inhalation (gas) induction with halothane or ether in oxygen or oxygen enriched air. Once

the patient is deeply anaesthetised they may be intubated whilst still in the lateral position. Cricoid

pressure is not necessary in this situation as any regurgitated material will automatically run out of

the mouth.

4. Fai led intubat ion. If intubation proves impossible then it is best to accept the situation and

adopt an alternative anaesthetic technique instead of wasting time with repeated intubation attempts.

The possible options are to continue with a mask anaesthetic (provided the airway is easy to

maintain while maintaining cricoid pressure) or to wake the patient up after turning them on their

side with the head down and attempt the procedure under local anaesthetic. Alternatively the

patient may be allowed to wake up and an awake tracheostomy or intubation performed. The best

course will depend on the condition of the patient and their degree of fasting, the operation

planned, the facilities and level of expertise available.

5. The cricoid cartilage is difficult to identify. Using firm pressure with your index finger follow a line

down the front of the neck from the front of the mandible. The first’ solid’ structure you meet is the

hyoid bone, followed by the thyroid cartilage (Adam’s apple) which is much more prominent in

males. Immediately below this you will feel a gap between the cricoid and thyroid cartilages

(the cricothyroid ligament) and then the cricoid cartilage. Encourage your assistants to practice

finding the cricoid cartilage on other colleagues until they are confident. Non-skilled assistants can

provide cricoid pressure if they receive adequate instruction and the position of the cricoid ring is

marked on the skin in ink before starting.

6. The patient regurgitates despite the application of cricoid pressure. If there is only a small quantity

of fluid suck it out of the pharynx and intubate the patient. Use a suction catheter to aspirate the

trachea after intubation. If there is copious fluid then the patient should be turned on to the side

and placed head down to protect the airway. Suction the pharynx and then intubate the patient.

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Note: When using small oxygen concentrators in association with draw over apparatus

preoxygenation may be difficult as the machines can only provide 4 litres per minute of around 85 -

90% oxygen. When this mixture is used the patient will always entrain air into the draw over circuit

making preoxygenation less efficient. One way round this is to fill a large plastic bag with 'oxygen'

from the concentrator and use this as an oxygen reservoir during preoygenation. When used it should

be attached to the inlet of the circuit. Remember to remove it before it empties completely.

Anticipated Difficult Intubation

Awake intubation. This technique can be used to place an endotracheal tube before inducing

anaesthesia. It is useful for patients in whom you expect intubation may be difficult and in whom

maintaining an airway under anaesthesia may become a problem.

The best technique uses a fibreoptic bronchoscope but these are rarely available. A simpler

technique is to give the patient a drying premedication with intramuscular atropine and then using

some plain 10% lignocaine spray inside the mouth and then ask them to move the solution around

the mouth. After a short time gently insert the laryngoscope as far as the patient will let you and

spray some more lignocaine into the airway further down, then remove the scope. By repeating

this maneouvre you will soon see the epiglottis and cords and after spraying them well you be able to

intubate the patient. Induce anaesthesia as soon as you have accomplished this. At all times be gentle

and consider using sedation such as low dose diazepam/midazolain and/or morphine to help you.

Be careful however, not to depress respiration.

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ANAESTHESIA FOR OBSTETRIC HAEMORRHAGE

Etiology o f Obstetr ic Haemorrhage and Som e Assoc iated Obstetr ic Risk

Factors.

Aetiology group Examples of risk factors

Placental abnormalities Congenital Bicornuate uterusLocation Placenta praevia

Attachment/invasion Placenta accreta/increta/percreta Acquired structural Leiomyoma, previous surgeryPeripartum Uterine inversion, uterine rupture, placental abruption

Coagulationl disorders Congenital Von Willebrand’s disease

Acquired DIC, dilutional coagulopathy, heparin

Lacerations and trauma Planned Caesarean section, episiotomyUnplanned Vaginal/cervical surgical trauma

Uterine atony Multiple gestation, high parity, prolonged labour.Choriomanionitis augmented labour, tocolytic agentsRetained uterine products of conception, blood clots

Causes of Obs tetr ic Haemorrhage

Antepartum Postpartum

Placenta praevia uterine atonyPlacental abruption genital traumaUterine rupture retained placentaVasa praevia placenta accreta

uterine inversion

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Symptoms asso ciated with Haemorrhage in Pregnancy

Class Acute Blood Loss (ml) % Lost Clinical findings

1. < 1000 15 None

2. 1200-1500 15-25 Mild hypotensian blood pressure changespulse pressure < 30 mm Hg,

Reduced peripheral perfusion withVasoconstrictionProlonged capillary refill time.

3. 1500-2000 25-35 Cold clammy skin, tachycardia, tachypnea,Hypotension, restlessness, Oliguria

4. > 2000 > 35 Profound shock, nonpalpable bloodPressure (BP L60 mHg) altered

consciousness. Amnesia

Management o f a Bleeding Parturient

Follow general principles of resuscitation (Airway, breathing, circulation)

Call for help

Try & make an early diagnosis and treat the cause

Begin large-bore intravenous line (14G / 16G one or two cannulae)

Order blood tests (haemoglobin, coagulation profile, cross match)

Order blood (haematology consultation, if possible)

Oxygen by mask at 8 lit/min Infuse crystalloid / colloid (Pentastarch/polygeline) to maintain isovolemia (warm all

fluids)

Start high-pressure infusion system

Pulse and BP monitoring with Oximeter and Non-invasive BP monitor

Consider use of Vasopressors – ephedeine or phenyl ephrine

Insert a central venous pressure line (after stabilization)

Begin prompt treatment of clotting disorders as soon as result obtained

Monitor urine output (Foley’s catheter)

Keep the patient warm

N.B. In case of a retained placenta, deep general anaesthesia, as with halothane, helps relaxthe uterus and makes removal of the products easier. Decrease the concentration of the inhaledagent as soon as this has been done so as to help the uterus to contract. Aslo start oxytoxin atthis stage.

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Obstetr ic Haemorrhage: Fluid Therapy

1. Initial therapy

Crystalloid (Ringer lactate/0.9% saline) maximum 2 litres

Colloid (hetastarch, polygeline, human albumin, 4.5%) maximum 1.5 litres

Do not use dextran

2. Transfuse blood as soon as possible

If cross-matched blood is still unavailable and 3.5 litres of crystalloid/colloid is infusedthen

Give ‘O’ negative blood or

Uncrossmatched, own group blood

3. If bleeding does not stop with initial therapy and results of coagulation studies are stillunavailable (Remember dilutional coagulopathy can also occur)

Give 1 litre fresh frozen plasma (FFP)

Give cryoprecipitate empirically

Use best equipment available to achieve rapid warmed infusion of fluids

N.B. Fresh whole blood may be used if FFP is not available.

Definit ive Treatment - Ato nic PPH

Bimanual uterine compression

Uterotonics- Syntocinon infusion (maximum 40 units in 1000 ml ringer lactate – 125 ml/hr)- Ergometrine 0.5 mg slow IV inj.

- 15 methyl PGF2 0.25 mg IM/IV

- Gemeprost rectal suppository 1000 g

Uterine and vaginal exploration

Consider angiographic embolizaion (ASE)

Initiate timely surgical haemostasis- Stepwise uterine devascularisation- B-lynch suture- Bilateral hypogastric artery ligation (BHAL)

- HysterectomyResort to hysterectomy sooner rather than later especially in cases of placenta accreta or uterine rupture

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COMMONLY USED UTEROTONICS

Commonly used uterotonics are:

Oxytoxin – 10-20 units added to 500 ml -1000 ml of Crystalloid

Methergin – Ergot derivative for uterine contraction 0.2 mgm deep IM/IV

Carboprost – 15 methyl prostaglandins 2 µgm (0.25 mgm) deep IM

Their effects are:

Oxytoxin – Tachycardia, Hypotension

Administer carefully in cardiac patients.

Methergin – Hypertension, Nausea and vomiting (can be severe), Headache

Carboprost – Bronchoconstriction, Nausea and vomiting

They are contra-indicated in cases as given below:

Methergin – Avoid in PIH, hypertension, ischaemic heart disease.

Carboprost – Contraindicated in asthmatics

Prophylactic antiemetics like odansteron 4 gm stat and Q6H may be required in case of use of Methergin or Carboprost.

TEACHING POINTS

1. The usual estimate of vaginal bleeding often does not reflect the extent of intravascular

volume deficit.2. The same patient may have more than one haemorrhagic disorder.

3. a) Uterine atony is the most common cause of post partum haemorrhage.

b) A history of caesarean section and current placenta praevia increases the probability

of placenta accreta which can result in massive obstetric haemorrhage.

4. Have a high index of suspicion.

a) Start extra large bore IV lines early (before the patient vasoconstricts).

b) Send off labs for PCV & coagulation studies.

c) Crossmatch blood early.d) Resuscitation with oxygen and ionotropes. Intubate and ventilate if required.

e) DO NOT consider spinal in this hypovolemic situation.

f) Ketamine is a good induction agent here (if GA is required).

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Algorithm for management of pregnant patient for non obstetric surgery

Pregnant patient for non obstetric surgery

Pre-operative evaluation

Assess urgency of surgery

Elective Semi-emergency Emergency

Postpone till after delivery Delay until II trimester

(if possible)

Post-operative careMonitor maternal vitals, FHR and uterine contractions

Uneventful recovery Potential complications

< 16 weeks gestation

Use non-participate antacidand full aspiration prophylaxis

Avoid N2O in high conc. DuringGA

Prefer regional anaesthesia

Maintain oxygenation eucapnia

Normotension euglycaemia. Monitor FHR

> 16 weeks gestation

Use non-participate antacid,full aspiration prophylaxis

Discuss use of tocolytics withObstetrician.

Maintain left uterineDisplacement.

Maintain oxygenation, eucapnianormotension and euglycaemia.Normotension euglycaemia.

Monitor FHR and uterineContradictions.

Maternal

Hypoxia

Hypotension

Premature labour

Thromboembolism

Foetal

Premature birth

Foetal wastage

Foetal asphyxia

Drug depression

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ANAESTHESIA FOR NON-OBSTETRIC SURGERY DURING

PREGNANCY4

The commonest indication for non obstetric surgery during pregnancy is appendectomy.

Cholecystectomy, trauma and cervical encirclage may be included in this group. The pregnant

patient undergoing surgery requires special attention to

1. Maternal safety

2. Protection of foetus against teratogenicity

3. Avoidance of intra uterine foetal hypoxia

4. Prevention of preterm labour.

PRE-OPERATIVE CONSIDERATIONS

Proper anaesthetic management of the pregnant surgical patient first requires diagnosis of the

pregnancy. All female patients of childbearing age should be questioned about the possibility of

pregnancy during pre-operative evaluation which may be confirmed by a pregnancy test if

required. Documentation of the last menstrual period should be on the anaesthetic record.

Elective surgical procedures should be postponed until after delivery. During pregnancy surgery

should only be entertained when the medical or surgical condition threatens maternal or foetal

well being.

During the pre-operative evaluation, risks to the foetus and possible loss of pregnancy should

be discussed by both the anaesthesiologist and surgeon. This is an excellent time to establish a

good rapport with the patient and alleviate maternal anxiety and minimize apprehension.

Adequate premedication should also be used to allay anxiety, both for the mother's comfort and

to prevent increased endogenous catecholamines which could decrease uterine perfusion.

Opioids or barbiturates rather than benzodiazepines are acceptable and safe for the foetus. Pre-

operative pain may be relieved by Acetaminophen or narcotic analgesics. Avoid Acetylsalicylic

acid and Non- steroidal anti-inflammatory agents.

Aspiration prophylaxis with an H2 receptor blocking agent and a non-particulate antacid should

be included as part of the pre-operative medication. Glycopyrrolate, a quarternary ammonium

compound with limited placental transfer, is a good choice as an anticholinergic anti sialagogue.

Prophylactic tocolysis with indomethacin suppositories (β-agonist drugs or magnesium sulphate)

should be started with obstetric consultation.

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If the gestation is more than 20 weeks, the patient should be given a left lateral position during

transport to the operating room and postoperatively, to prevent aortocaval compression.

The intravascular volume status should be normal or slightly elevated. Those patients who are

to undergo major conduction blockade should receive a preinduction fluid load of at least 500

ml-1 litre of crystalloid solution to avoid hypotension.

MONITORING

Monitoring of maternal blood pressure, oxygenation (both by inspired oxygen concentration and

pulse oximeter) ventilation (preferably by end tidal carbon dioxide) and temperature are

mandatory. Hypoglycemia should be avoided and hence intra-operative blood glucose

monitoring should be done.

To monitor the foetal heart rate, an external Doppler device should be used after 16 weeks

gestation, taking care that the transducer does not encroach on the surgical field.

Foetal decelerations can indicate inadvertent maternal hypoxemia during surgery, which could

be corrected by a higher inspired oxygen concentration or repositioning of the endotracheal

tube. Hypoxia is probably the most common teratogen and cause of foetal distress during

surgery. Decelerations may also indicate inadequate uterine perfusion, which could be

corrected by increasing left uterine displacement or increasing maternal mean pressure with

fluids or pressor agents such as ephedrine. Beat to beat variability will be decreased or lost after

use of opioids, barbiturates and other anaesthetic agents. This effect may persist post

operatively until the foetus excretes these agents, even after the mother has recovered.

Uterine activity should be monitored intra operatively through use of an external

tocodynamometer. This monitor may aid in the early diagnosis of uterine irritability. An external

tocodynamometer may be difficult to place and maintain during surgery but it should be used in

the immediate post operative period so that the obstetrician may elect to begin pharmacologic

tocolysis, if uterine contractions are detected.

INTRA OPERATIVE MANAGEMENT

A. Regional Anaesthesia

The minimal drug exposure conferred by regional anaesthesia makes this technique preferable

over general anaesthesia, an important consideration in the first trimester. If no sedative or

narcotic supplementation is given, there should be no change in foetal heart rate variability, to

confuse foetal monitoring in the postoperative period. Some important points to remember

during regional anaesthesia are the following:

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1. Avoid hypotension by adequately preloading with fluids and maintaining left uterine

displacement.

2. Local anaesthetic requirements are decreased even in I trimester of pregnancy.

3. Ephederine is the vasopressor of choice to combat hypotension as it preserves the uterine

blood flow, although phenylephrine has also been used successfully without adverse neonatal

effects.

4. Adequate oxygenation through a ventimask is useful to assure maternal safety and prevent

intra uterine asphyxia, especially in foetal distress.

B. General Anaesthesia

There is no evidence that any anaesthetic agent or technique is safer than the other as long as

maternal tissue perfusion and oxygenation are maintained within normal limits. Placental blood

flow decreases with maternal hypotension, mechanical ventilation, pain or apprehension,

increased uterine activity and the administration of vasoconstrictor agents.

Some important points to remember during general anaesthesia are:

1. Preoxygenate the patient for 5 minutes to prevent rapid desaturation.

2. A rapid sequence induction with cricoid pressure will decrease the risk of aspiration • along

with aspiration prophylaxis.

3. If ketamine is used as an induction agent, use doses < 2 mg / kg to prevent increases in

uterine tone.

4. Inhalational anaesthetic agents are known to decrease uterine tone and inhibit contractions.

Halogenated anaesthetics in doses above 2.0 MAC decrease maternal blood pressure and

cardiac output leading to foetal acidosis.

5. Use of N2O is controversial as it may decrease uterine blood flow. Some centres avoid its use

in the first trimester of pregnancy or pretreat with folic acid before surgery.

6. Current non-depolarizing muscle relaxants can be used safely as they do not have adverse

neonatal effects. Reversal with neostigmine, may theoretically cause an increase in uterine tone

by increasing the release of acetylcholine. Ideally they should be given slowly and in

combination with an anticholinergic agent like glycopyrrolate or atropine

Thus a safe anaesthetic management is more important than technique or agent along with

avoidance of hypoxia, hyperventilation and hypotension.

In summary, for non obstetric surgery during pregnancy, keep these points in mind:1. Postpone elective surgery until after delivery.2. Urgent surgery, if possible, should be deferred until the II and III trimester.

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3. For emergency surgery during trimester, regional anaesthesia (if surgical and maternalconditions allow) is considered safe.

4. Local anaesthetic exposure in foetus following spinal anaesthesia is less than other regional blocks.

5. Allay maternal anxiety and apprehension during the pre-operative visit.6. During general anaesthesia, avoid hyperventilation and provide adequate oxygenation.

7. Risk of gastric aspiration and pneumonitis is increased during pregnancy. Usualsafeguards should be used to prevent it.

8. To avoid aortocaval compression, a left lateral tilt should be used whenever possible.9. After the 16th week of gestation, foetal heart rate monitoring will forewarn any

abnormalities in maternal ventilation or uterine perfusion during surgery.10. Continuous monitoring of uterine activity during the postoperative period can detect

onset of preterm labour.11. Early institution of tocolytic therapy can prevent preterm delivery.

CARDIAC ARREST ASSOCIATED WITH PREGNANCY5

Adapted from Circulat ion, 2005;112:IV-150-IV-153 This special supplement to Circu lation is freely available at http://www.circulationaha.org

I would advise you to read the whole issue on CPR.

During attempted resuscitation of a pregnant woman, providers have two potential patients, the

mother and the fetus. The best hope of fetal survival is maternal survival. For the critically ill

patient who is pregnant, rescuers must provide appropriate resuscitation, with consideration of

the physiologic changes due to pregnancy.

Key Interventions to prevent Arrest

To treat the critically ill pregnant patient:

Place the patient in the left lateral position (see below)

Give 100% oxygen

Establish intravenous (IV) access and give a fluid bolus.

Consider reversible causes of cardiac arrest and identify any preexisting medical conditions

that may be complicating the resuscitation.

http://www.circulationaha.org/




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PRIMARY AND SECONDARY ABCD SURVEY: MODIFICATION FORPREGNANT WOMEN

ACLS* Approach Modification to BLS** and ACLS Guidelines

Primary ABCD Survey Airway Clear airway, head tilt, chin lift, jaw thrust / O2

Breathing

Look, Listen, FeelCirculation

Push hard / push fast : 30/2 (compression/ventilation)

Place the woman or her left side with her back angled15° to 30° back from the left lateral position. then start chestcompressions.

or

Place a wedge under the woman’s right side (so that shetilts toward her left side)

or Have one helper kneel next to the woman’s left side and

pull the gravid uterus laterally. This maneuver will relievepressure on the inferior vena cava.

Defibrillation

Biphasic 200J monophasic 360J single shock & continueCPR.Do not stop CPR for checking Rhythm for 2 mins or 5cycles of 30:2.

Defibrillation shocks transfer no significant current to thefetus.

Remove any fetal or uterine monitors before shock delivery.

* ACLS: Advanced Cardiac Life Support** BLS: Basic Life Support

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Secondary ABCD Survey Airway

Insert an advanced airway early in resuscitation to reducethe risk of regurgitation and aspiration

Airway oedema and swelling may reduce the diameter of the trachea. Be prepared to use a tracheal tube that is

slightly smaller than the one you would use for anonpregnant woman of similar size.

Monitor for excessive bleeding following insertion of anytube into the oropharynx or nasopharynx.

No modifications to intubation techniques. A provider experienced in intubation should insert the tracheal tube.

Effective preoxygenation is critical because hypoxia candevelop quickly.

Rapid sequence intubation with continuous cricoid pressureis the preferred technique.

Agents for anesthesia or deep sedation should be selectedto minimize hypotension.

Breathing

No modifications of confirmation of tube placement. Notethat the esophageal detector device may suggestesophageal placement despite correct tracheal tubeplacement

The gravid uterus elevates the diaphragm:- Patients can develop hypoxemia if either oxygen demandor pulmonary function is compromised. They have lessreserve because functional residual capacity and functionalresidual volume are decreased. Minute ventilation andtidal volume are increased- Tailor ventilatory support to produce effective oxygenationand ventilation.

Circulation

Follow standard ACLS recommendations for administrationof all resuscitation medications.

Do not use the femoral vein or other lower extremity sitesfor venous access. Drugs administered through these sitesmay not reach the maternal heart unless or until the fetus isdelivered.

Differential Diagnosis and Decisions

Decide whether to perform emergency hysterotomy.Identify and treat reversible causes of the arrest. Consider causes related to pregnancy and

causes considered for all ACLS patients.

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RESUSCITATION OF THE PREGNANT WOMAN IN CARDIAC ARREST5

Modifications of Basic Life Support

Several modifications to standard BLS approaches are appropriate for the pregnant woman in

cardiac arrest. At a gestational age of 20 weeks and beyond, the pregnant uterus can press

against the inferior vena cava and the aorta, impeding venous return and cardiac output.

Uterine obstruction of venous return can produce pre arrest hypotension or shock and in the

critically ill patient may precipitate arrest. In cardiac arrest the compromise in venous return and

cardiac output by the gravid uterus limits the effectiveness of chest compressions. The gravid

uterus may be shifted away from the inferior vena cava and the aorta by placing the patient 15°

to 30° back from the left lateral position (Class IIa) or by pulling the gravid uterus to the side.

This may be accomplished manually or by placement of a rolled blanket or other object under

the right hip and lumbar area. Other modifications are discussed below.

Airway and breathing

- Hormonal changes promote insufficiency of the gastroesophageal sphincter,

increasing the risk of regurgitation. Apply continuous cricoid pressure during

positive pressure ventilation for any unconscious pregnant woman.

Circulation

- Perform chest compressions higher on the sternum, slightly above the center of the

sternum. This will adjust for the elevation of the diaphragm and abdominal

contents caused by the gravid uterus.

Defibrillation

- Defibrillate using standard ACLS defibrillation does (Class IIa). Review the ACLS

Pulseless Arrest Algorithm There is no evidence that shocks from a direct current

defibrillator have adverse effects on the heart of the fetus.

- If fetal or uterine monitors are in place, remove them before delivering shocks.

Modifications of Advanced Cardiovascular Life Support

The treatments listed in the standard ACLS Pulseless Arrest Algorithm, including

recommendations and doses for defibrillation, medications, and intubation, apply to cardiac

arrest in the pregnant woman. There are important consideration to keep in mind, however,

about airway, breathing, circulation, and the differential diagnosis.

Airway

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- Secure the airway early in the resuscitation. Because of the potential for

gastroesophageal sphincter insufficiency with an increased risk of regurgitation, use

continuous cricoid pressure before and during attempted endotracheal intubation.

- Be prepared to use an endotracheal tube 0.5 to 1 mm smaller in internal diameter than

that used for a nonpregnant woman of similar size because the airway may be narrowed

from edema.6

Breathing

- Pregnant patients can develop hypoxemia rapidly because they have decreased

functional residual capacity and increased oxygen demand, so rescuers should be

prepared to support oxygenation and ventilation.

- Verify correct endotracheal tube placement using clinical assessment and a device such

as an exhaled CO2 detector. In late pregnancy the esophageal detector device is more

likely to suggest esophageal placement (the aspirating bulb does not reinflate after

compression) when the tube is actually in the trachea. This could lead to the removal of

a properly placed endotracheal tube.

- Ventilation volumes may need to be reduced because the mother’s diaphragm is elevated.

Circulation

- Follow the ACLS guidelines for resuscitation medications.

- Vasopressor agents such as epinephrine, vasopressin, and dopamine will decrease blood

flow to the uterus. There are no alternatives, however, to using all indicated medications

in recommended doses. The mother must be resuscitated or the chances of fetal

resuscitation vanish.

Differential diagnoses. The same reversible causes of cardiac arrest that occur in non

pregnant women can occur during pregnancy. But providers should be familiar with

pregnancy-specific diseases and procedural complications. Providers should try to identify

these common and reversible causes of cardiac arrest in pregnancy during resuscitation

attempts. The use of abdominal ultrasound by a skilled operator should be considered in

detecting pregnancy and possible causes of the cardiac arrest, but this should not delay

other treatments.

- Excess magnesium sulfate. Iatrogenic overdose is possible in women with eclampsia who

receive magnesium sulfate, particularly if the woman becomes oliguric. Administration of

calcium gluconate (1 ampoule or 1 g) is the treatment of choice for magnesium toxicity. Empiric

calcium administration may be lifesaving.

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Acute coronary syndromes. Pregnant women may experience acute coronary syndromes,

typically in association with other medical conditions. Because fibrinolytics are relatively

contraindicated in pregnancy, percutaneous coronary intervention is the reperfusion strategy of

choice for ST-elevation myocardial infarction.

- Pre-eclampsia/eclampsia. Pre-eclampsia/eclampsia develops after the 20th week of gestation

and can produce severe hypertension and ultimate diffuse organ system failure. If untreated it

may result in maternal and fetal morbidity and mortality.

- Aortic dissection. Pregnant women are at increased risk for spontaneous aortic dissection.

- Life-threatening pulmonary embolism and stroke. Successful use of fibrinolytics for a

massive, life-threatening pulmonary embolism and ischemic stroke have been reported in

pregnant women.

- Amniotic fluid embolism. Clinicians have reported successful use of cardiopulmonary bypass

for women with life-threatening amniotic fluid embolism during labor and delivery.15

- Trauma and drug overdose. Pregnant women are not exempt from the accidents and mental

illness that afflict much of society. Domestic violence also increases during pregnancy; in fact,

homicide and suicide are leading causes of mortality during pregnancy.

Emergency Hysterotomy (Cesarean Delivery) for the Pregnant Woman in Cardiac Arrest

Maternal Cardiac Arrest Not Imm ediately Reversed by BL S and ACLS

The resuscitation team leader should consider the need for an emergency hysterotomy

(cesarean delivery) protocol as soon as a pregnant woman develops cardiac arrest.

The best survival rate for infants >24 to 25 weeks in gestation occurs when the delivery of the

infant occurs no more than 5 minutes after the mother’s heart stops beating. This typically

requires that the provider begin the hysterotomy about 4 minutes after cardiac arrest.

Emergency hysterotomy is an aggressive procedure. It may seem counterintuitive given that

the key to salvage of a potentially viable infant is resuscitation of the mother. But the mother

cannot be resuscitated until venous return and aortic output are restored. Delivery of the baby

empties the uterus, relieving both the venous obstruction and the aortic compression. The

hysterotomy also allows access to the infant so that newborn resuscitation can begin.

The critical point to remember is that you will lose both mother and infant if you cannot restore

blood flow to the mother’s heart Note that 4 to 5 minutes is the maximum time rescuers will have

to determine if the arrest can be reversed by BLS and ACLS interventions. The rescue team is

not required to wait for this time to elapse before initiating emergency hysterotomy. Recent

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reports document long intervals between an urgent decision for hysterotomy and actual delivery

of the infant, far exceeding the obstetrical guideline of 30 minutes.

Establishment of IV access and an advanced airway typically requires several minutes. In most

cases the actual cesarean delivery cannot proceed until after administration of IV medications

and endotracheal intubation. Resuscitation team leaders should activate the protocol for an

emergency cesarean delivery as soon as cardiac arrest is identified in the pregnant woman. By

the time the team leader is poised to deliver the baby, IV access has been established, initial

medications have been administered, an advanced airway is in place, and the immediate

reversibility of the cardiac arrest has been determined.

Decision Making for Emergency Hysterotom y

The resuscitation team should consider several maternal and fetal factors in determining the

need for an emergency hysterotomy.

Consider gestational age. Although the gravid uterus reaches a size that will begin to

compromise aortocaval blood flow at approximately 20 weeks of gestation, fetal viability

begins at approximately 24 to 25 weeks. Portable Ultrasonography, available in some

emergency departments, may aid in determination of gestational age (in experienced hands)

and positioning. However, the use of ultrasound should not delay the decision to perform

emergency hysterotomy.

- Gestational age <20 weeks. Urgent cesarean delivery need not be considered because a

gravid uterus of this size is unlikely to significantly compromise maternal cardiac output.

- Gestational age approximately 20 to 23 weeks. Perform an emergency hysterotomy to

enable successful resuscitation of the mother, not the survival of the delivered infant,

which is unlikely at this gestational age.

- Gestational age approximately > 24 to 25 weeks. Perform an emergency hysterotomy to

save the life of both the mother and the infant.

Consider features of the cardiac arrest. The following features of the cardiac arrest can

increase the infant’s chance for survival:

- Short interval between the mother’s arrest and the infant’s delivery

- No sustained prearrest hypoxia in the mother

- Minimal or no signs of fetal distress before the mother’s cardiac arrest

- Aggressive and effective resuscitative efforts for the mother

- The hysterotomy is performed in a medical center with a neonatal intensive care unit

Consider the professional setting:

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- Are appropriate equipment and supplies available?

- Is emergency hysterotomy within the rescuer’s procedural range of experience and

skills?

- Are skilled neonatal/pediatric support personnel available to care for the infant,

especially if the infant is not full term?

- Are obstetric personnel immediately available to support the mother after delivery?

Advance Preparation

Experts and organizations have emphasized the importance of advance preparation. Medical

centers must review whether performance of an emergency hysterotomy is feasible at their

center, and if so, they must identify the best means of rapidly accomplishing this procedure.

The plans should be made in collaboration with the obstetric and pediatric services.

Summary

Successful resuscitation of a pregnant woman and survival of the fetus require prompt and

excellent CPR with some modifications in basic and advanced cardiovascular life support

techniques. By the 20th week of gestation, the gravid uterus can compress the inferior vena

cava and the aorta, obstructing venous return and arterial blood flow. Rescuers can relieve this

compression by positioning the woman on her side or by pulling the gravid uterus to the side.

Defibrillation and medication doses used for resuscitation of the pregnant woman are the same

as those used for other adults in pulseless arrest. Rescuers should consider the need for

emergency hysterotomy as soon as the pregnant woman develops cardiac arrest because

rescuers should be prepared to proceed with the hysterotomy if the resuscitation is not

successful within minutes.

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ADDITIONAL READINGS

PHYSIOLOGICAL CHANGES ASSOCIATED WITH PREGNANCY1

Physiological and anatomical alterations develop in many organ systems during the course of

pregnancy and delivery. Early changes are due, in part, to the metabolic demands brought on bythe fetus, placenta and uterus, and in part, to the increasing levels of pregnancy hormones,

particularly those of progesterone and oestrogen. Later changes, starting in mid-pregnancy, are

anatomical in nature and are caused by mechanical pressure from the expanding uterus. These

alterations create unique requirements for the anaesthetic management of the pregnant

woman.

CARDIOVASCULAR SYSTEM

The pregnancy-induced changes in the cardiovascular system develop primarily to meet

the increased metabolic demands of the mother and fetus.

Blood Volume increases progressively from 6-8 weeks gestation (pregnancy) and reaches

a maximum at approximately 32-34 weeks with little change thereafter. Most of the added

volume of blood is accounted for by an increased capacity of the uterine, breast, renal, striated

muscle and cutaneous vascular systems, with no evidence of circulatory overload in the healthy

pregnant woman. The increase in plasma volume (40-50%) is relatively greater than that of red

cell mass (20-30%) resulting in hemodilution and a decrease in hemoglobin concentration. Intake

of supplemental iron and folic acid is necessary to restore hemoglobin levels to normal (12 g/dl). The

increased blood volume serves two purposes. First, it facilitates maternal and fetal exchanges of

respiratory gases, nutrients and metabolites. Second, it reduces the impact of maternal blood

loss at delivery. Typical losses of 300-500 ml for vaginal births and 750-1000 ml for

Caesarean sections are thus compensated with the so-called "autotransfusion" of blood from

the contracting uterus.

Blood Constituents. As mentioned above, red cell mass is increased 20-30%. Leukocyte counts

are variable during gestation, but usually remain within the upper limits of normal. Marked

elevations, however, develop during and after parturition (delivery). Fibrinogen, as well as total

body and plasma levels of factors VII, X and XII increase markedly. The number of platelets also

rises, yet not above the upper limits of normal. Combined with a decrease in fibrinolytic activity,

these changes tend to prevent excessive bleeding at delivery. Thus, pregnancy is a relatively

hypercoagulable state, but during pregnancy neither clotting nor bleeding times are abnormal.

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Cardiac Output increases to a similar degree as the blood volume. During the first trimester

cardiac output is 30-40% higher than in the non-pregnant state. Steady rises are shown on

Doppler echocardiography, from an average of 6.7litres/ minute at 8-11 weeks to about

8.7litres/minute flow at 36-39 weeks; they are due, primarily, to an increase in stroke volume

(35%) and, to a lesser extent, to a more rapid heart rate (15%). There is a steady reduction in

systemic vascular resistance (SVR) which contributes towards the hyper dynamic circulation

observed in pregnancy.

During labor, further increases are seen with pain in response to increased catecholamine secretion;

this increase can be blunted with the institution of labor analgesia. Also during labor, there is

an increase in intravascular volume by 300-500 ml of blood from the contracting uterus to the

venous system. Following delivery, this auto transfusion compensates for the blood losses and

tends to further increase cardiac output by 50% of pre-delivery values. At this point, stroke

volume is increased while heart rate is slowed.

Cardiac Size/Position/ECG: There are both size and position changes which can lead to

changes in ECG appearance. The heart is enlarged by both chamber dilation and hypertrophy.

Dilation across the tricuspid valve can initiate mild regurgitant flow causing a normal grade I or II

systolic murmur. Upward displacement of the diaphragm by the enlarging uterus causes the heart

to shift to the left and anteriorly, so that the apex beat is moved outward and upward. These

changes lead to common ECG findings of left axis deviation, sagging ST segments and frequently

inversion or flattening of the T-wave in lead III.

Blood Pressure. Systemic arterial pressure is never increased during normal gestation. In fact,

by midpregnancy, a slight decrease in diastolic pressure can be recognized. Pulmonary arterial

pressure also maintains a constant level. However, vascular tone is more dependent upon

sympathetic control than in the nonpregnant state, so that hypotension develops more readily

and more markedly consequent to sympathetic blockade following spinal or extradural

anaesthesia. Central venous and brachial venous pressures remain unchanged during

pregnancy, but femoral venous pressure is progressively increased due to mechanical factors.

Aortocaval Compression (Supine Hypotension). From mid-pregnancy, the enlarged uterus

compresses both the inferior vena cava and the lower aorta when the patient lies supine.

Obstruction of the inferior vena cava reduces venous return to the heart leading to a fall in cardiac

output by as much as 24% towards term. In the unanaesthetised state, most women are

capable of compensating for the resultant decrease in stroke volume by increasing systemic

vascular resistance and heart rate. There are also alternative venous pathways, the

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paravertebral and azygous systems. During anesthesia, however, these compensatory

mechanisms are reduced or abolished so that significant hypotension may rapidly develop.

Obstruction of the lower aorta and its branches causes diminished blood flow to kidneys,

uteroplacental unit and lower extremities. During the last trimester, maternal kidney function is

markedly lower in the supine than in the lateral position. Furthermore, the fetus is compromised

by insufficient transplacental gas exchange.

Venous Distension increases approximately to 150% during the course of gestation and the

venous ends of capillaries become dilated, causing reduced blood flow. These vascular changes

contribute to delayed absorption of subcutaneously or intramuscularly injected substances.

Distension of the extradural veins heightens the risk of vascular damage during institution of a

regional block. The increased venous volume within the rigid spinal canal reduces the volume

or capacity of the extradural and intrathecal spaces for local anaesthetic solutions. This will

therefore increase the spread of injected drugs.

Clinical Implications: Despite the increased workload of the heart during gestation and labor,

the healthy woman has no impairment of cardiac reserve. In contrast, for the gravid with heart

disease and low cardiac reserve, the increase in the work of the heart may cause ventricular failure

and pulmonary edema. In these women, further increases in cardiac workload during labor

must be prevented by effective pain relief, optimally provided by extradural or spinal analgesia.

Since cardiac output is highest in the immediate postpartum period, sympathetic blockade

should be maintained for several hours after delivery and then weaned off slowly.

RESPIRATORY SYSTEM

Changes within the respiratory system are of great significance to the anaesthetist.

Respiratory Tract: Hormonal changes to the mucosal vasculature of the respiratory tract lead to

capillary engorgement and swelling of the lining in the nose, oropharynx, larynx, and trachea.

Symptoms of nasal congestion, voice change and upper respiratory tract infection may prevail

throughout gestation. These symptoms can be exacerbated by fluid overload or oedema

associated with pregnancy-induced hypertension (PIH) or pre-eclampsia. In such cases, manipulation

of the airway can result in profuse bleeding from the nose or oropharynx; endotracheal

intubation can be difficult; and only a smaller than usual endotracheal tube may fit through the

larynx. Airway resistance is reduced, probably due to the progesterone-mediated relaxation of

the bronchial musculature.

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Lung Volumes: Upward displacement by the gravid uterus causes a 4 cm elevation of the

diaphragm, but total lung capacity decreases only slightly because of compensatory increases in

the transverse and antero-posterior diameters of the chest, as well as flaring of the ribs. These

changes are brought about by hormonal effects that loosen ligaments. Despite the upward

displacement, the diaphragm moves with greater excursions during breathing in the pregnant than

in the non-pregnant state. In fact, breathing is more diaphragmatic than thoracic during

gestation, an advantage during supine positioning and high regional blockade.

From the middle of the second trimester, expiratory reserve volume, residual volume and

functional residual volume are progressively decreased, by approximately 20% at term. Lung

compliance is relatively unaffected, but chest wall compliance is reduced, especially in the

lithotomy position.

Ventilation and Respiratory Gases: A progressive increase in minute ventilation starts soon after

conception and peaks at 50% above normal levels around the second trimester. This increase is

effected by a 40% rise in tidal volume and a 15% rise in respiratory rate (2-3 breaths/minute).

Since dead space remains unchanged, alveolar ventilation is about 70% higher at the end of

gestation. Arterial and alveolar carbon dioxide tensions are decreased by the increased ventilation.

An average PaCO2 of 32mmHg (4.3 kPa) and arterial oxygen tension of 105mmHg (13.7 kPa)

persist during most of gestation. The development of alkalosis is forestalled by

compensatory decreases in serum bicarbonate. Only carbon dioxide tensions below 28mmHg

(3.73 kPa) will lead to a respiratory alkalosis.

During labor, ventilation may be further accentuated, either voluntarily (Lamaze method of

pain control and relaxation) or involuntarily in response to pain and anxiety. Such excessive

hyperventilation results in marked hypocarbia and severe alkalosis, which can lead to cerebral

and uteroplacental vasoconstricton and a left shift of the oxygen dissociation curve. The latter

reduces the release of oxygen from hemoglobin with consequent decreased maternal tissue

oxygenation as well as reduced oxygen transfer to the fetus. Furthermore, episodes of

hyperventilation may be followed by periods of hypoventilation as the blood carbon dioxide tension

(PaCO2) returns to normal. This may lead to both maternal and fetal hypoxia.

Oxygen consumption increases gradually in response to the needs of the growing fetus,

culminating in a rise of at least 20% at term. During labor, oxygen consumption is further increased

(up to and over 60%) as a result of the exaggerated cardiac and respiratory work load.

Clinical Implications: The changes in respiratory function have clinical relevance for the

anesthesiologist. Most importantly, increased oxygen consumption and the decreased reserve

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due to the reduced functional residual capacity, may result in rapid falls in arterial oxygen tension

despite careful maternal positioning and preoxygenation. Even with short periods of apnea,

whether from obstruction of the airway or inhalation of a hypoxic mixture of gas, the gravid has little

defense against the development of hypoxia. The increased minute ventilation combined with

decreased functional residual capacity hastens inhalation induction or changes in depth of

anaesthesia when breathing spontaneously.

GASTROINTESTINAL SYSTEM

Since aspiration of gastric contents is an important cause of maternal morbidity and mortality in

association with anesthesia, we will examine the controversy surrounding gastrointestinal

changes in pregnancy.

Mechanical Changes: The enlarging uterus causes a gradual cephalad displacement of stomach

and intestines. At term the stomach has attained a vertical position rather than its normalhorizontal one. These mechanical forces lead to increased intragastric pressures as well as a

change in the angle of the gastroesophageal junction, which in turn tends toward greater

oesophageal reflux.

Physiological Changes: The hormonal effects on the gastrointestinal tract are an issue of

debate among anaesthetists. Relaxation of the lower oesophageal sphincter has been

described, but there have been differing views about the effect on motility of the gastrointestinal tract

and the times at which it is most prominent. Many believe that there is also retardation of

gastrointestinal motility and gastric emptying, producing increased gastric volume with decreased

pH, beginning as early as 8-10 weeks of gestation. Recent studies, however, have shed a

different light on the subject. Measuring peak plasma concentrations of drugs absorbed exclusively in

the duodenum in both non-pregnant and pregnant volunteers, at different times of gestation, it

was shown that peak absorption occurred at the same interval in all women with the exception

those in labor. This suggests that gastric emptying is delayed only at the time of delivery. Thus,

the raised risk of aspiration is due to an increase of oesophageal reflux and decreased pH of

gastric contents. The heightened incidence of difficult endotracheal intubations worsens the

situation.

TEACHING POINT The gravida should be considered to be a "full stomach" patient with increased risk of

aspiration during most of gestation.

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Pulmonary Aspiration of gastric contents can occur either following vomiting (active) or

regurgitation (passive). Aspiration of solid material causes atelectasis, obstructive pneumonitis or

lung abscess, while aspiration of acidic gastric contents results in chemical pneumonitis

(Mendelson's syndrome). The most serious consequences following aspiration of acidic materials

containing particulate matter as may follow swallowing certain antacids such as magnesium

trisilicate. Clear antacids such as sodium citrate (0.3 Mol) or bicarbonate should be used. While

the incidence of pulmonary aspiration of solid food has decreased due to patient education, that of

gastric acid has remained constant.

Clinical Implications: The danger of aspiration is almost eliminated when regional anaesthesia

or inhalational analgesia is used. During general anaesthesia airway protection by means of a

cuffed endotracheal tube is mandatory. Although awake intubation is safest, discomfort and the

lack of patient cooperation and discomfort prevent it being the routine method for securing the

airway. The endotracheal tube is placed immediately following loss of consciousness after

induction of general anesthesia.

The acidity and volume of gastric content can be reduced by pharmacologic interventions which

may prove invaluable. Most importantly, a non particulate oral antacid, 30ml of sodium citrate 0.3

Mol or bicarbonate, may be given immediately prior to induction of general anesthesia to all

women. In addition, if available, metoclopramide, 10 mg IV, should be administered 1 5 - 3 0

minutes before induction to promote gastric emptying and increase the lower oesophageal

sphincter tone. This is especially beneficial in women in labor who have not been starved and

TEACHING POINT

Special precautions should be needed, even when induction to intubation time is

expected to be brief, to prevent regurgitation:

a) supine posi tion wit h l ateral tilt to minimize any increase in intragastric

pressure

b) preoxygenation prior to induction, then no positive pressure ventilation prior to

insert ion of the endotracheal tube to prevent distention of the stomach with gas

(rapid sequence induction)

c) cricoid pressure (Sellick's maneuver)during induction which is maintained until

endotracheal tube placement in the trachea has been confirmed. Cricoid

pressure should be applied to the cricoid carti lage whilst support ing the

back of the neck. This occludes the oesophagus, thus obstructing the path of

regurgitation.

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require emergency surgery. Lastly, histamine H2 - receptor antagonist the night before and the

morning of delivery may reduce secretion of hydrochloric acid (ranitidine 150mg orally).

METABOLISM

All metabolic functions are increased during pregnancy to provide for the demands of fetus,

placenta and uterus as well as for the gravida's increased basal metabolic rate and oxygen

consumption. Protein metabolism is enhanced to supply substrate for maternal and fetal growth.

Fat metabolism increases as evidenced by elevation in all lipid fractions in the blood.

Carbohydrate metabolism, however, demonstrates the most dramatic changes. Metabolically

speaking, pregnant women live in a state of "accelerated starvation." First, nutritional demands of

the growing fetus are met by the intake of glucose and, second, secretion of insulin in response to

glucose is augmented. As early as 15 weeks of gestation, maternal blood glucose levels after

an overnight fast are considerably lower than in the nongravid state.

Hypoglycemia: Optimal blood glucose levels in pregnant women range between 4.4 to 5.5mmol/1

(80 to 100mg/dl). In healthy non-pregnant individuals, signs of hypoglycemia usually begin

when the blood glucose level declines to approximately 2.2mmol/1 (40mg/dl); in pregnant

women, however, hypoglycemia is defined as a concentration below 3.3mmol/1 (60mg/dl).

Hypoglycemia initiates the release of glucagon, cortisol and, importantly, catecholamines. In the

anaesthetized state, however, these compensatory mechanisms, particularly the release of

epinephrine (adrenaline), are blocked. Autonomic derangements in the form of hypotension and

tachycardia tend to ensue during high regional blockade or deep general anaesthesia, which may

mask the symptoms and signs of hypoglycemia.

RENAL PHYSIOLOGY

Renal plasma flow and glomerular filtration rate begin to increase progressively during the first

trimester. At term, both are 50-60% higher than in the non-pregnant state. This parallels the

increases in blood volume and cardiac output. The elevations in plasma flow and glomerular filtration

result in an elevation in creatinine clearance. Blood urea and serum creatinine are reduced by

40%. The increase in glomerular filtration may overwhelm the ability of the renal tubules to

reabsorb leading to glucose and protein losses in the urine. Thus, mild glycosuria (1-10gm/day)and/or proteinuria (to 300mg/day) can occur in normal pregnancy. There is also an increase in

filtered sodium, but tubular absorption is increased by an increase in aldosterone secretion, via the

renin-angiotensin mechanism.

There is also a decrease in plasma osmolality. This is a measure of the osmotic activity of a

substance in solution and is defined as the number of osmoles in a kilogram of solvent. In practice

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it indicates that the plasma concentrations of electrolytes, glucose and urea, fall if more water

than sodium, for example, is retained. Over the whole period of gestation there is retention of

7.5L of water and 900mmol of sodium.

After the 12th week of gestation, progesterone can induce dilation and atony of the renal calyses

and ureters. With advancing gestation, the enlarging uterus can compress the ureters as they

cross the pelvic brim and cause further dilatation by obstructing flow. These changes may

contribute to the frequency of urinary tract infections during pregnancy. The effect of postural

compression of the aortic branches perfusing the kidneys has been discussed.

DRUG RESPONSES

The response to anaesthetic and adjuvant drugs is modified during pregnancy and the early

puerperium. The most pertinent alteration is a reduced drug requirement, manifest in both regional

and general anaesthesia.

Regional Anaesthesia: From the late first trimester to the early puerperium, a smaller dose of

local anaesthetic is required to obtain the desired level of spinal or extradural blockade. During the

last months of gestation, approximately two-thirds of the normal dose is adequate. This altered

response, which is due to CSF and hormonal changes and an increase in volume of the

epidural veins, subsides progressively in the early postpartum period.

General Anaesthesia: Induction and changes in depth of inhalation anaesthesia occur with

greater rapidity in pregnant women than in non-pregnant subjects. Pregnancy enhances

anaesthetic uptake in two ways. 1) The increase in resting ventilation delivers more agent into

the alveoli per unit time, while 2) the reduction in functional residual capacity favors rapid

replacement of lung gas with the inspired agent. In addition, there is a reduction in anaesthetic

requirements, with a fall in the minimum alveolar concentrations (MAC) of halogenated vapors.

When measured in ewes MAC was 25-40% lower in gravid as compared with nonpregnant

animals.

The decreased functional residual capacity has a further effect on the management of general

anaesthesia. As referred to earlier, the resultant reduction in oxygen storage capacity, together

with the elevated oxygen consumption, leads to an unusually rapid decline in arterial oxygen

tension in the apneic anaesthetized gravid.

There are also alterations in the response to intravenous agents, in particular prolongation of

their elimination half-lives consequent to the greater distribution volume (resulting from the

pregnancy-induced increase in plasma volume). Thus, the mean elimination half-life for

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thiopentone in gravid women is more than doubled in comparison with that in nongravid young

patients.

Serum Cholinesterase: Serum cholinesterase levels fall by 24-28% during the first trimester

without a marked change for the remainder of gestation. However, even lower levels (about 33%

reduction) develop during the first 7 postpartum days. The decreased levels of the enzyme are

still sufficient for normal hydrolysis of clinical doses of suxamethonium or chloroprocaine during

gestation. Postpartum, however, approximately 10% of women will be at risk of a prolonged

reaction to suxamethonium.

Clinical Implication: These altered drug responses must be taken into consideration whenever a

patient is pregnant or in the early puerperium.

MONITORING DURING CAESAREAN SECTION7

Recommendations for monitoring during Caesarean section (CS) have been developed by the

American Board of Anesthesiologists and the Obstetric Anaesthetists Associat ion (OAA) in the

UK. The OAA's recommendations are reproduced in full in Box 1. Not all anaesthetists have access to

complex equipment, but every anaesthetist should be aware of the potential problems that may be

encountered and make appropriate use of the monitors they do have. The requirements for regional and

general anaesthetics are different and so considered separately. All obstetric patients undergoing

CS should be positioned with left lateral tilt to avoid aorto-caval compression.

Regional anaesthesia

Most of the monitoring is clinical since awake mothers are excellent monitors of their own physiology. The

anaesthetist should be continuously present from the start of anaesthesia to the completion of surgery.

Assessment of analgesia

A major cause of maternal complaint is pain during LSCS under regional anaesthesia. For LSCS, a

block should extend from S4 to the upper thoracic dermatomes. One common reason for inadequate pain

relief is a failure of the block to spread to the sacral dermatomes. Although this happens more

frequently with epidural than spinal anaesthesia, whichever technique is used, always test the back

of the legs (S2 and S3) to confirm that the sacral dermatomes are blocked before surgery starts.

How high a regional block must extend into the thoracic dermatomes to achieve intraoperative

analgesia remains controversial. Recommendations from T10 to T4 have been made, although the

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method of testing the block is often unspecified and the need for supplemental analgesics not

mentioned. The three most commonly used methods of assessment are:

• loss of temperature sensation

• loss of pinprick sensation

• loss of light touch sensation

These may differ by as much as 10 dermatomes, with temperature sensation lost first and light touch

sensation last. Experimental data suggests that intraoperative analgesia is most reliably predicted by

blocking light touch sensation (the hub of a needle lightly applied to the skin) to T5 (just beneath the

nipples).

It is worth telling the mother that she might feel pressure as the baby is delivered.

Haemodynamic consequences of regional anaesthesia

Extensive epidural and spinal blocks cause a temporary sympathectomy which makes the patient

susceptible to hypotension. In pregnant women, this is made worse by the uterus compressing the

aorta and inferior vena cava (aorto-caval occlusion). Hypotension may develop rapidly. Therefore, blood

pressure should be measured at least every two minutes from starting a regional block until

delivery. Nausea during onset of a regional block is usually an indication of hypotension.

Recommendations for monitoring during caesarean section

For operative delivery under regional block

Continuous pulse oximetry, non invasive blood pressure and continuous ECG during

induction, maintenance and recovery.

The fetal heart rate should be recorded during initiation of regional block and until abdominal skin

preparation in emergency caesarean section.

During general anaesthesia

Continuous inspired oxygen and end-tidal carbon dioxide concentration should be

monitored, as well as pulse oximetry, non-invasive blood pressure and ECG.

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Blocks above T4 cause a loss of sympathetic innervation to the heart which may be associated with

bradycardia particularly if aorto-caval occlusion is present. Because of this continuous monitoring of

the pulse is essential.

Respiratory consequences of regional anaesthesia

Pregnant women are prone to hypoxia because of a reduction in functional residual capacity (FRC) of

the lungs and an increased oxygen consumption. This is compounded during regional blocks by abdominal

and intercostal muscle weakness which causes a further reduction in FRC. Pulse oximetry not only

monitors the pulse but also provides a continuous non-invasive monitor of the saturation of arterial

haemoglobin. It is simple and accurate; always use it if you can.

When the thoracic dermatomes are blocked, patients often complain of a strange sensation when

breathing, usually as they realise that they cannot produce a forceful cough. This is normal and a result

of intercostal paralysis and the patient can be reassured. However difficulty in speaking represents

diaphragmatic paralysis developing and needs very careful assessment of the level of block. Further

spread of local anaesthetic must be minimised. If hyperbaric local anaesthetic has been used,

this can be done by careful elevation of the head and neck. However be prepared to intubate and

support such patients’ ventilation.

Unexpected high blocks

"Total spinals" or very high blocks may follow excessive spread of a deliberate intrathecal injection of

local anaesthetic or be caused by an epidural catheter that is misplaced in the subarachnoid space.

Misplaced epidural catheters can be detected by attempting to aspirate CSF through the catheter and

carefully assessing the effect produced by a test dose. An appropriate test dose will produce

detectable changes in sensory and motor function within five minutes of injection if the catheter is in the

subarachnoid space, and no significant effect if the catheter is in the epidural space.

The spread of deliberate intrathecal injections of hyperbaric (heavy) local anaesthetics can be controlled

by keeping the upper thoracic and cervical spine elevated. As spinal blocks sometimes extend very

rapidly, you must check the spread of the block within 4 minutes of injection and reposition the patient if

necessary.Symptoms of high blocks are predictable. As the block extends the hands become warm and dry,

then loss of hand and arm movement follows. Loss of abduction of the shoulder may be rapidly

followed by diaphragmatic paralysis. At the same time sensation is lost over the upper chest, hands,

arms, shoulder and neck. If the block extends further, consciousness may be lost and the pupils may

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become fixed and dilated. However all these signs will reverse provided cardiovascular and

respiratory support are provided.

Regional blocks may continue to extend for at least 30 minutes after local anaesthetic has been

injected, so the anaesthetist must remain vigilant for symptoms of high blocks even after surgery has

started.

Monitoring the injection of local anaesthetic

Accidental intravenous injection of local anaesthetics may occur with epidural anaesthesia and although

deaths are rare, convulsions occur in 1 in 500 - 9000 patients. This risk can be minimised by carefully

aspirating before each injection, by assessing the effect of a small initial test dose of local anaesthetic and

by splitting all large doses of local anaesthetics into several small portions. Every dose must be assessed

for symptoms of intravenous injection (Table below) even when previous doses have been

uncomplicated.

Symptoms of intravenous injection of local anaesthetic

Tingling around the mouth

Tinnitus (ringing in the ears)

Visual disturbance

Confusion

Slurred speech

Altered conscious state

Convulsions

Coma

Cardiovascular collapse

Cardiac arrhythmias

General anaesthesia

Patients undergoing LSCS performed under general anaesthesia should be monitored in the

same way as with any general anaesthetic. The obstetric anaesthetist should be particularly aware of

airway problems and episodes of hyper- or hypotension.

Monitors of intubation

Failure of intubation and oxygenation remains one of the commonest causes of anaesthetic related

maternal deaths. Confirmation of the correct placement of an endotracheal (ET) tube is crucial. Various

monitors are available to help the anaesthetist, but seeing the ET tube pass through the glottis remains

the most valuable. However the presence of bilateral breath sounds should always be checked and,

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when possible, the presence of expired CO2 confirmed. The table on pg.97 shows ten simple clinical

tests of correct placement of a tracheal tube.

The oesophageal detection device is a useful additional monitor. It is cheap and easily constructed

using a 50 ml syringe or a self inflating bulb. If a negative pressure is applied by the syringe to a

correctly positioned endotracheal (ET) tube, gas can be aspirated because the trachea is supported

by rigid cartilage. However if the ET tube is misplaced in the oesophagus and a negative pressure

applied, the oesophagus will obstruct the tip of the ET tube and gas cannot be aspirated.

Monitors of ventilation

As with regional anaesthesia the pregnant mother is vulnerable to hypoxia; look at the patient's

colour of the blood and at movement of the chest wall. If you are ventilating by hand, feel for any changes

in resistance to ventilation - if you are using ventilator, look regularly at and make a note of the inflation

pressure. Always use a pulse oximeter if you have one.

Haemodynamic consequences of general anaesthesia

Aorto-caval occlusion means that mothers are vulnerable to hypotension, while hypertension may

occur with laryngoscopy and surgical stimulus. Pre-eclamptic mothers are particularly vulnerable to

hypertension on laryngoscopy. So, as with regional anaesthesia, blood pressure must be measured at

least every two minutes until delivery, and the pulse must be continuously mentioned.

Monitors for awareness

To reduce fetal depression and uterine relaxation, anaesthetists have sometimes used low doses of anaesthetic agents in a paralysed mother during CS. This has resulted in some mothers being awake and

in severe pain. No single monitor reliably predicts awareness, although signs of sympathetic

stimulation - sweating, tachycardia, hypertension and pupillary dilation - should always be

regarded with concern.

The most reliable method of ensuring the mother is asleep is to give adequate doses of induction agents

and an initial overpressure of inhalational agents.

Neuromuscular blockade

With modern short acting muscle relaxants, reversal of neuromuscular block at the end of

caesarean section is rarely a problem. The exception is if the mother has been treated with magnesium

sulphate. Magnesium enhances the action of non-depolarising muscle relaxants. So in these patients,

assessing neuromuscular function is important, ideally with a nerve stimulator; but alternatively, clinical

methods may be used, such as assessment of hand grip or sustained head lift.

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Various monitors of fetal condition are available. Fetal heart rate (FHR) monitoring is the most common.

The FHR may be recorded intermittently with a stethoscope, by abdominal ultrasound, or with a fetal

scalp electrode. A normal FHR has a 95% association with good fetal condition, and a prolonged

and continuing bradycardia is almost always associated with severe fetal distress.

During LSCS, the FHR should be monitored from the start of anaesthesia until abdominal skin

preparation especially if the fetus is already distressed. Knowing that the FHR is not critical, may allow

time for a regional technique to be used, when otherwise a general anaesthetic might have to be

performed. Knowledge of the FHR is also useful if a failed intubation occurs during general

anaesthesia. The FHR can influence the decision to either wake the mother and perform a regional

technique, or continue surgery with a face mask.

CLINICAL TESTS OF TRACHEAL INTUBATION Test Result Significance Reliability

Look with laryngoscope Tube passes betweencords

Correct tracheal intubation Certain

Listen/feel Breathing through tube Correct tracheal intubation Probable

Tap sternum Air comes out throughtracheal tube

Correct tracheal intubation Probable

Inflate with SIB* Chest rises & falls Correct tracheal intubation Probable

Inflate with SIB* Gurgling noise Oesophageal intubation(REMOVE TUBE)

Probable

Pass catheter down insidetube

Patient coughs (if notparalysed)


Look Patient remains pinkafter intubation


Look Patient becomescyanosed after intubation

Oesophageal intubation(REMOVE TUBE)

Certain

Stethoscope Air entry at both apicesboth axillae & both bases


Stethoscope Air entry over stomach

Oesophageal intubation(REMOVE TUBE)

Probable

* = self inflating bag.

The capnograph or an oesophageal detection device (see above) are the most useful pieces

of equipment to confirm intubation

Special problems.

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While the monitoring requirements for uncomplicated Caesarean deliveries are straightforward,

additional monitors may be required if other pathologies are present. Haemorrhage, embolism,

hypertensive disorders of pregnancy and maternal cardiac conditions are associated with more than

50% of maternal deaths.

Major haemorrhage

Major haemorrhage may be life threatening. Whenever major haemorrhage occurs, invasive

cardiovascular monitoring should be used if available. This should include hourly urine output

measurement, temperature monitoring and central venous pressure and invasive arterial pressure

monitoring (if available).

Embolism

The triad of hypocapnia, hypoxia and hypotension should alert the anaesthetist to the possibility of an

embolism. Air embolism, thromboembolism and amniotic fluid embolism may all occur. Minor air

embolism can be detected in almost every caesarean section. However it is extremely unusual for

this to have any clinical significance. Thromboembolism causes approximately 25% of UK

maternal deaths, but rarely presents during surgery. Perioperatively, amniotic fluid embolism is the

greatest risk. If embolism is suspected then invasive cardiovascular monitoring should be considered

and the clotting cascade assessed. Amniotic fluid embolism is often associated with coagulopathy.

Hypertensive disorders of pregnancy

Severe pre-eclampsia is associated with a reduced plasma volume, while total body water is increased.

Laryngeal oedema may make intubation difficult and hypertensive responses to intubation may be

greatly increased. Treatment with magnesium may prolong the action of muscle relaxants. Renal

failure may be present. Monitoring should be tailored to detect these problems and particular consideration

given to invasive monitoring of central venous pressure, arterial blood pressure and hourly urine output.

Maternal cardiac conditions

Pregnancy stresses the cardiovascular system, particularly at delivery, when large fluid shifts and rapid

changes in the pre- and after-load of the heart occur. These changes may be compounded by

anaesthesia. Patients with cardiac disease, especially significant shunts or stenotic valvular lesions,

are vulnerable to these changes. Some patients will require invasive cardiac monitoring throughout

the perioperative period.

Conclusions

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Caesarean sections are so common that the risks are often ignored. However in a recent survey, 82% of

anaesthetic related deaths occurred during Caesarean section. The obstetric anaesthetist can

reduce the risk to his patients by careful monitoring. The monitors should be tailored to detecting the

problems that may be encountered so that they can be corrected before mother or fetus are harmed.

WHY REGIONAL ANAESTHESIA IN OBSTETRIC PRACTICE

Regional anaesthesia is one of most useful tools in anaesthesiology. It provides good

operative anaesthesia combined with postoperative analgesia with minimal adverse effects.

Subarchnoid, epidural analgesia, and peripheral nerve block, have revolutionized the

treatment of the emergency obstetrics. Regional anaesthesia has been shown to be safer to

general anaesthesia, however controversies still exist. The principal advantages of regionalanaesthesia are as follows –

1) Decreased blood loss during surgery.

2) Minimal haemodynamic changes

3) Reduced thromboembolic events.

4) Early ambulation.

5) Comparatively easy postoperative course.

6) Lack of adverse effects of inhaled anaesthetics in susceptible individuals.

SPINAL ANAESTHESIA - A PRACTICAL GUIDE8

Spinal anaesthesia is induced by injecting small amounts of local anaesthetic into the cerebro-

spinal fluid (CSF). The injection is usually made in the lumbar spine below the level at which the

spinal cord ends (L2). Spinal anaesthesia is easy to perform and has the potential to provide

excellent operating conditions for surgery below the umbilicus.

If the anaesthetist has an adequate knowledge of the relevant anatomy, physiology and

pharmacology, safe and satisfactory anaesthesia can easily be obtained to the mutual

satisfaction of the patient, surgeon and anaesthetist.

The Advantages of Spinal Anaesthesia

Cost. Anaesthetic drugs and gases are costly and the latter often difficult to transport. The costs

associated with spinal anaesthesia are minimal.

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Patient satisfaction. If a spinal anaesthetic and the ensuing surgery are performed skillfully, the

majority of patients are very happy with the technique and appreciate the rapid recovery and

absence of side-effects.

Respiratory disease. Spinal anaesthesia produces few adverse effects on the respiratory

system as long as unduly high blocks are avoided.

Patent airway. As control of the airway is not compromised, there is a reduced risk of airway

obstruction or the aspiration of gastric contents. This advantage maybe lost with too much

sedation.

Diabetic patients. There is little risk of unrecognised hypoglycaemia in an awake patient.

Diabetic patients can usually return to their normal food and insulin regime soon after surgery as

there is less sedation, nausea and vomiting.

Muscle relaxation. Spinal anaesthesia provides excellent muscle relaxation for lower abdominal and lower limb surgery.

Bleeding. Blood loss during operation is less than when the same operation is done under

general anaesthesia. This is as a result of a decreased blood pressure and heart rate, and

improved venous drainage which results in less oozing.

Splanchnic blood flow. Because of its effect on increasing blood flow to the gut, spinal

anaesthesia reduces the incidence of anastomotic dehiscence.

Visceral tone. The bowel is contracted by spinal anaesthesia and sphincters relaxed

although peristalsis continues. Normal gut function rapidly returns following surgery.

Coagulation. Post-operative deep vein thromboses and pulmonary emboli are less common

following spinal anaesthesia.

Disadvantages of Spinal Anaesthesia

1. When an anaesthetist is learning a new technique, it will take longer to perform than when he is

more practised, and it would be wise to let the surgeon know that induction of anaesthesia may

be longer than usual. Once competent, however, spinal anaesthesia can be very swiftly

performed.

2. Occasionally, it is impossible to locate the dural space and obtain CSF and the technique has to

be abandoned. Rarely, despite an apparently faultless technique, anaesthesia is not obtained.

3. Hypotension may occur with higher blocks and the anaesthetist must know how to manage

this situation with the necessary resuscitative drugs and equipment immediately at hand. As with

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general anaesthesia, continuous, close monitoring of the patient is mandatory.

4. Some patients are not psychologically suited to be awake, even if sedated, during an

operation. They should be identified during the preoperative assessment.

5. Even if a long-acting local anaesthetic is used, a spinal is not suitable for surgery lasting longer

than approximately 2 hours. It is difficult for a patient to be flat and still for longer. If an operation

unexpectedly lasts longer than this, it may be necessary to convert to a general anaesthetic.

6. There is a theoretical risk of introducing infection into the subarachnoid space and causing

meningitis. This should never happen if equipment is sterilised properly and an aseptic technique

is used.

7. A postural headache may occur postoperatively. This should be rare: see later.

Indications for Spinal Anaesthesia

Spinal anaesthesia is best reserved for operations below the umbilicus e.g. hernia repairs,

gynecological and urological operations and any operation on the perineum or genitalia. All

operations on the leg are possible, but an amputation, though painless, may be an unpleasant

experience for an awake patient. In this situation it may be kinder to supplement the spinal with

generous sedation or a light general anaesthetic. IV Midazolam is a good choice as it provides

retrograde amnesia.

Spinal anaesthesia is especially indicated for older patients and those with systemic disease such

as chronic respiratory disease, hepatic, renal and endocrine disorders such as diabetes. Most

patients with mild cardiac disease benefit from the vasodilation that accompanies spinalanaesthesia except those with stenotic valvular disease or uncontrolled hypertension.

It is suitable for managing patients with trauma if they have been adequately resuscitated and are

not hypovolaemic. In obstetrics, it may be used for manual removal of a retained placenta

(again, provided there is no hypovolaemia). However it does not relax the uterine muscle. There are

definite advantages for both mother and baby in using spinal anaesthesia for Caesarean section.

However, special considerations apply to managing spinal anaesthesia in pregnant patients

(see later) and it is best to become experienced in its use in the non-pregnant patient before

using it for obstetrics.

Contra-indications to Spinal Anaesthesia

Most of the contra-indications to spinal anaesthesia apply equally to other forms of regional

anaesthesia. These include:

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Inadequate resuscitative drugs and equipment. No regional anaesthetic technique should be

attempted if drugs and equipment for resuscitation are not immediately to hand.

Clotting disorders. If bleeding occurs into the epidural space because an epidural vein has

been punctured by the spinal needle, a haematoma could form and compress the spinal cord.

Patients with a low platelet count or receiving anticoagulant drugs such as heparin or warfarin are

at risk. Remember that patients with liver disease may have abnormal clotting profiles whilst low

platelet counts as well as abnormal clotting can occur in pre-eclampsia.

Hypovolaemia from whatever cause e.g. bleeding, dehydration due to vomiting, diarrhoea or

bowel obstruction. Patients must be adequately rehydrated or resuscitated before spinal

anaesthesia or they will become very hypotensive.

Any sepsis on the back near the site of lumbar puncture.

Patient refusal. Patients may be understandably apprehensive and initially state a preferencefor general anaesthesia, but if the advantages of spinal anaesthesia are explained they may then

agree to the procedure and be pleasantly surprised at the outcome. If, despite adequate

explanation, the patient still refuses spinal anaesthesia, their wishes should be respected.

Uncooperative patients. Although spinal anaesthesia is suitable for children, their cooperation is

necessary and this must be carefully assessed at the pre-operative visit. Likewise, mentally

handicapped patients and those with psychiatric problems need careful pre-operative

assessment.

Septicaemia. Due to the presence of infection in the blood there is a possibility of such patients

developing meningitis if a haematoma forms at the site of lumbar puncture and becomes infected.

Anatomical deformities of the patient's back. This is a relative contraindication, as it will probably

only serve to make the dural puncture more difficult.

Neurological disease. The advantages and disadvantages of spinal anaesthesia in the presence

of neurological disease need careful assessment. Any worsening of the disease postoperatively

may be blamed erroneously on the spinal anaesthetic. Raised intracranial pressure, however, is an

absolute contra-indication as a dural puncture may precipitate coning of the brain stem.

Reluctant surgeon. If a surgeon is unhappy operating on an awake patient or if he is relatively

unskilled, spinal anaesthesia may be better avoided.

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Controv ersies in spinal anaesthesia

Operator/anaesthetist. The same individual should not be responsible for over-seeing the

anaesthetic and performing the surgery as "anaesthetic" problems can occur during the course of

the operation. If such problems occur once surgery has started, the safety of the patient may be

severely compromised. However, in many places doctors perform a spinal anaesthetic and then

delegate intra-operative care of the patient to a suitably trained assistant while the surgery is

performed.

Difficult airway . At first sight, spinal anaesthesia may appear to offer an ideal solution to the problem of

a patient with a potentially difficult airway who requires lower abdominal surgery. However, the onset

of a total spinal block or unforeseen surgical complications may make it imperative that the airway is

secured. All the equipment necessary for intubation should, therefore, always be available before

spinal anaesthesia is commenced. It is always an extremely difficult to decide on whether to

embark on a spinal anaesthetic when a patient is known to be difficult to intubate. The correct decision

can only be made by the individual anaesthetist when all relevant clinical information is taken into

account.

Physiolog y of Spinal Anaesthesia

Local anaesthetic solution injected into the subarachnoid space blocks conduction of impulses

along all nerves with which it comes in contact, although some nerves are more easily blocked

than others.

There are three classes of nerves: motor, sensory and autonomic. The motor convey messages for

muscles to contract and when they are blocked, muscle paralysis results. Sensory nerves transmit

sensations such as touch and pain to the spinal cord and from there to the brain, whilst autonomic

nerves control the calibre of blood vessels, heart rate, gut contraction and other functions not

under conscious control.

Generally, autonomic and pain fibres are blocked first and motor fibres last. This has several

important consequences. For example, vasodilation and a drop in blood pressure may occur

when the autonomic fibres are blocked and the patient may be aware of touch and yet feel no pain

when surgery starts.

There are practical implications associated with these physiological phenomena.

- The patient should be well hydrated before the local anaesthetic is injected and should have

an intravenous infusion in place so that further fluids or vasoconstrictors can be given if

hypotension occurs.

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- The site to be operated on should not be repeatedly touched and the patient asked "Can you feel

this?" as this increases the patient's anxiety. Often some sensation of touch or movement

remains and yet no pain is felt. It is better to pinch the skin gently either with artery forceps or

fingers and ask if it is painful. If it is not then surgery can begin.

Anatomy

The spinal cord usually ends at the level of L2 in adults and L3 in children. Dural puncture above

these levels is associated with a slight risk of damaging the spinal cord and is best avoided. An

important landmark to remember is that a line joining the top of the iliac crests is at L4 to

L4/ 5

Remember the structures that the needle will pierce before reaching the CSF.

The skin. It is wise to inject a small bleb of local anaesthetic into the skin before inserting the

spinal needle.

Subcutaneous fat. This, of course, is of variable thickness. Identifying the intervertebral spaces

is far easier in thin patients.

The supraspinous ligament which joins the tips of the spinous processes together.

The interspinous ligament which is a thin flat band of ligament running between the spinous

processes.

The ligamentum flavum is quite thick, up to about 1cm in the middle and is mostly composed of

elastic tissue. It runs vertically from lamina to lamina. When the needle is within the ligaments itwill feel gripped and a distinct "give" can often be felt as it passes through and into the epidural

space.

The epidural space contains fat and blood vessels. If blood comes out of the spinal needle

instead of CSF when the stylet is removed, it is likely that an epidural vein has been punctured. The

needle should simply be advanced a little further.

The dura. After feeling a "give" as the needle passes through the ligamentum flavum, a similar

sensation may be felt when the needle is advanced a short distance further and pierces the dural

sac.

The subarachnoid space. This contains the spinal cord and nerve roots surrounded by CSF. An

injection of local anaesthetic will mix with the CSF and rapidly block the nerve roots with which it

comes in contact.

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ligament Interspinous ligament Vertebral body ligament

Ligamentumflavum

Supraspinous Post. Long

Ligament

Figure: Section of lumbar vertebrae to show the ligaments.

Local Anaesthetics for Spinal Anaesthesia

Local anaesthetic agents are either heavier (hyperbaric), lighter (hypobaric), or have the same

specific gravity (isobaric) as the CSF. Hyperbaric solutions tend to spread below the level of the

injection, while isobaric solutions are not influenced in this way. It is easier to predict the spread of

spinal anaesthesia when using ahyperbaric agent. Isobaric preparations may be made hyperbaric by

the addition of dextrose. Hypobaric agents are not generally available. The other factors affecting

the spread of local anaesthetic agents when used for spinal blocks are described later.

Bupivacaine (Marcaine). 0.5%hyperbaric (heavy) bupivacaine is the best agent to use if it is

available. 0.5% plain bupivacaine is also popular. Bupivacaine lasts longer than most other spinal

anaesthetics: usually 2-3 hours.

Lignocaine (qn/Xylocaine). Best results are obtained with 5% hyperbaric (heavy) lignocaine which

lasts 45-90 minutes. 2% lignocaine can also be used but it has a much shorter duration of action. If

0.2ml of adrenaline 1:1000 is added to the lignocaine, it will usefully prolong its duration of

action. Lignocaine from multi-dose vials should not be used for intrathecal injection as it contains

potentially harmful preservatives.

Spinal Anaesthesia and Common Medical Conditions

Ant.long,

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Respiratory Disease. A low spinal block has no effect on the respiratory system and is

therefore ideal for patients with respiratory disease unless they cough a lot. Frequent coughing

results in less than ideal conditions for the surgeon. A high spinal block can produce intercostal

muscle paralysis, but this does not usually create any problems, unless the patient is very

limited by his respiratory disease.

Hypertension. Hypertension is not a contraindication to spinal anaesthesia but, ideally, it

should be controlled before any anaesthetic is administered. Hypertensive patients should have

their blood pressure closely monitored during the anaesthetic and any episode of hypotension

vigorously treated.

Sickle cell disease/trait. Spinal anaesthesia may be advantageous for patients with sickle cell

disease. Follow the same rules as for general anaesthesia: ensure that the patient is well

oxygenated, well hydrated and not allowed to become hypotensive. Consider warming the

intravenous fluids and do not allow the patient to become cold. Avoid the use of tourniquets.

Pre-operative Visit

Patients should be told about their anaesthetic during the pre-operative visit. It is important to

explain that although spinal anaesthesia abolishes pain, they may be aware of some sensation

in the relevant area, but it will not be uncomfortable and is quite normal. It should also be

explained that their legs will become weak or feel as if they don't belong to them anymore. They

must be reassured that, if they feel pain they will be given a general anaesthetic.

Premedication is not always necessary, but if a patient is apprehensive, a benzodiazepine such

as 5-10 mg of diazepam may be given orally 1 hour before the operation. Other sedative or

narcotic agents may also be used. Anticholinergics such as atropine or scopolamine (hyoscine) are

unnecessary.

Pre-loading

All patients having spinal anaesthesia must have a large intravenous cannula inserted and be

given intravenous fluids immediately before the spinal. The volume of fluid given will vary with the

age of the patient and the extent of the proposed block. A young, fit man having a hernia repair

may only need 500 mls. Older patients are not able to compensate as efficiently as the young for

spinal-induced vasodilation and hypotension and may need 1000mls for a similar procedure. If

a high block is planned, at least a 1 000mls should be given to all patients. Caesarean section

patients need at least 1500 mls.

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The fluid should preferably be normal saline or Hartmann's solution. 5% dextrose is readily

metabolised and so is not effective in maintaining the blood pressure.

Positioning the Patient for Lumbar Puncture

Lumbar puncture is most easily performed when there is maximum flexion of the lumbar spine.The figures below show the effect of flexion and extension on the lumbar intervertebral space.

Flexion

Extension

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This can best be achieved by sitting the patient on the operating table and placing their feet on a

stool. If they then rest their forearms on their thighs, they can maintain a stable and comfortable

position.

Ideal sitting position for spinal anaesthesia.

Alternatively, the procedure can be performed with the patient lying on their side with their hips

and knees maximally flexed. An assistant may help to maintain the patient in a comfortable curled

position. The sitting position is preferable in the obese whereas the lateral is better for

uncooperative or sedated patients. The anaesthetist can either sit or kneel whilst performing the

block.

Factors Affecting the Spread of the Local Anaesthetic Solution

A number of factors affect the spread of the injected local anaesthetic solution within the CSF and

the ultimate extent of the block obtained. Among these are:

- the baricity of the local anaesthetic solution

- the position of the patient

- the concentration and volume injected

- the level of injection

- the speed of injection

The specific gravity of the local anaesthetic solution can be altered by the addition of dextrose.

Concentrations of 7.5% dextrose make the local anaesthetic hyperbaric (heavy) relative to CSF

and also reduce the rate at which it diffuses and mixes with the CSF. Isobaric and hyperbaric

solutions both produce reliable blocks. The most controllable blocks are probably produced by

injecting hyperbaric solutions and then altering the patient's position.

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If a patient is kept sitting for several minutes after the injection of a small volume of a hyperbaric

solution of local anaesthetic, a classical saddle block of the perineum will result. The spinal column

of patients lying on their side is rarely truly horizontal. Males tend to have wider shoulders than

hips and so are in a slight "head up" position when lying on their sides, whilst for females with

their wider hips, the opposite is true. Regardless of the position of the patient at the time of

injection and whatever the initial extent of the block obtained, the level of the block may change if

the patient's position is altered within twenty minutes of the injection.

The quantity of local anaesthetic (in milligrams) injected will determine the quality of the block

obtained whilst its extent will also be determined by the volume in which it is injected. Large volumes

of concentrated solutions will, thus, produce dense blockade over a large area.

Note how the level of the subarachnoid space varies between male and female because

females have broad hips and males broad shoulders.

Hips vertical Knees drawn up to chest

Female

Back in flexion at

edge of tableShoulders vertical

Female

Male

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Although the level of injection will obviously affect which dermatomes are blocked, spinal injections

tend to be performed only in the lower lumbar region. The extent of the block is influenced more

by the volume injected and the position of the patient than the actual inter space at which the

injection occurs.

The speed of injection has a slight effect on the eventual extent of the block. Slow injections

result in a more predictable spread while rapid injections produce eddy currents within the CSF

and a somewhat less predictable outcome.

Finally, increased abdominal pressure from whatever cause (pregnancy, ascites, etc) can lead

to engorgement of the epidural veins, compression of the dura and hence a reduction in the volume

of the CSF. A given quantity of local anaesthetic injected into the CSF might then be expected to

produce a more extensive block.

PRACTICAL PROBLEMS WITH SPINAL ANAESTHESIA

(1) The spinal needle feels as if it is in the right position but no CSF appears.

Wait at least 30 seconds, then try rotating the needle 90 degree and wait again. If there is still

no CSF, attach an empty 2ml syringe and inject 0.5-1 ml of air to insure the needle is not blocked, then

use the syringe to aspirate whilst slowly with-drawing the spinal needle. Stop as soon as CSF

appears in the syringe.

(2) Blood flows from the spinal needle.

Wait a short time. If the blood becomes pinkish finally clear, all is well. If blood only continues

to drip, then it is likely that the needle tip is in the epidural vein and it should be advanced a little further

to pierce the dura.

(3) The patient complains of sharp, stabbing leg pain.

The needle has hit a nerve root because it has deviated laterally. Withdraw the needle and

redirect it more medially away from the affected side.

(4) Wherever the needle is directed, it seems to strike bone.

Make sure the patient is still properly positioned with as much lumbar flexion as possible and

that needle is still in midline. If you are not sure whether you are in midline, ask the patient on which

side they feel the needle. Alternatively, in pregnant patients, who cannot bend very much or have

calcified interspinous ligaments; it might be better to attempt a para median approach to dura. Head

end approach with legs extended on operation table in sitting position is possibly most ideal position

for conduct of spinal anaesthesia in pregnant patients.

(5) The patient complains of pain during needle insertion.

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This suggests that the spinal needle is passing through the muscle on either side of the

ligaments. Redirect your needle away from the side of the pain to get back into the midline or inject

some local anaesthetic.

(6) The patient complains of pain during injection of the spinal solution.

Stop injecting and change the position of needle, or try a different space.

PHARMACOLOGY OF VASOPRESSORS AND INOTROPES3

A "vasopressor" causes vasoconstriction and an "inotrope" increases the force of cardiac contraction.

Vasopressors and inotropes work via the Autonomic Nervous System.

Neurotransmission at postganglionic receptors. The postganglionic receptors of the

Parasympathetic Nervous System PNS are termed muscarinic, and acetylcholine (Ach) is the

neurotransmitter. The equivalent receptors in the Sympathetic Nervous System (SNS) arenoradrenergic

receptors and noradrenaline (Norad) is the endogenous (naturally occurring) neurotransmitter (table 1).

These noradrenergic receptors are further subdivided, the subdivisions relevant to this article are Alpha1 (α

1), Beta1 (β1), Beta2 (β2) and Dopamine (D). The main actions of each receptor subtype are as shown

in table 2.

VASOPRESSORS AND INOTROPES

This group of drugs is useful for resuscitation of seriously ill patients, and for the treatment of hypotension in

theatre. All of these drugs act directly or indirectly on the SNS, but the effect of each varies

according to which sympathetic receptor the drug has greatest affinity for. The duration of action also

varies. Direct acting drugs act by stimulating the SNS receptor whereas indirect acting drugs cause

the release of noradrenaline from the receptor which produces the effect. Some drugs have a mixed effect.

ADRENALINE (EPINEPHRINE)

Adrenaline acts on α 1, β1 and β2 receptors. It is said to prepare the body for a "fight or flight"response.

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Preganglionic receptor type Post ganglionic receptor type(and neurotransmitter) (and neurotransmitter)

PNS Nicotinic (Ach) Muscarinic (Ach)

SNS Nicotinic (Ach) Noradrenergic (Norad)

Actions

CVS: Increased heart rate and force of contraction produce an increase in cardiac

output. Systolic blood pressure (SBP) rises, but with low doses diastolic blood pressure

(DBP) may fall due to vasodilation and increased blood flow through skeletal muscle beds (β2).

At higher doses the vasoconstrictor effects of α 1 stimulation become more apparent, causing

the cool pale extremities of a frightened person.

RS: Bronchial smooth muscle is relaxed resulting in bronchodilation (β2).

Other: Adrenaline mobilises glucose from glycogen and raises blood sugar. Pupillary dilation

(mydriasis) occurs.

Side effects Ventricular arrhythmias, hypertension. Care with halothane anaesthesia as

arrhythmias may occur.

Preparation 1:1000 i.e. 1mgin 1 ml. 1:10,000 i.e. 1mgin 10ml

Indications and doses

Cardiac Arrest

Anaphylact ic shock - 1:10,000 adrenaline given iv in 1 ml doses until effective. If no iv

access available then 0.5ml of 1:1,000 im.

Addit ive to local anaesthetic - add adrenaline to local anaesthetic to make a concentration

of 1:200,000 – (0.1ml of adrenaline 1:100 to 20ml of local anaesthesia)

Acute severe asthma attack unresponsive to normal treatment may require infusions of

adrenaline, though 0.5ml of 1:1000 s/c may be used.

Septic shock - require infusions of adrenaline

Length of action Short, few minutes only with intravenous bolus.

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EPHEDRINE

Ephedrine acts directly on β1 and β2 receptors, and indirectly on α1 receptors by

causing noradrenaline release.

Action It causes a rise in blood pressure and heart rate, and some bronchodilation.

Side effects May cause tachycardia and hypertension. Possible arrhythmias if used with

halothane.

Preparation 3% or 5% solution: 1 ml ampoules.

Indications Low blood pressure due to vasodilation e.g. following spinal or epidural

anaesthesia and drug overdoses. Best vasopressor to use in pregnancy as it does not reduce

placental blood flow.

Dose 3-10 mg boluses iv, repeat until effective. Maximum dose is 60mg.

Length of action 5-15 minutes, repeated doses less effective (i.e. it demonstrates

tachyphylaxis).

METHOXAMINE

Methoxamine acts on α1 receptors.

Actions Increases blood pressure. There may be a reflex decrease in heart rate, and

therefore it is good for hypotension with tachycardia. Useful during spinal anaesthesia.

αl Peripheral arteriolar vasoconstrictionCardiac increased heart rate and force of contraction

β2 Bronchial smooth muscle dilation.Vasodilation in skeletal muscle. Also some cardiac effects.

D Increased renal blood flow

Side effects May produce bradycardia Dose 2-4mg boluses IV, repeated as necessary.

METARAMINOL

Acts directly on α1 receptors and also causes noradrenaline and adrenaline release.

Actions Increases blood pressure and cardiac output. Less likely to cause a reflex bradycardia than

methoxamine or phenylephrine.

Dose -1 mg boluses iv, 2-1 0mg s/c or im, by infusion at 1-20mg/hr.

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PHENYLEPHRINE

Acts directly on α1 receptors,

Action Hypertension and a reflex decrease in heart rate.

Dose 2-5mg im or sc, 0.1-0.5mgiv, by infusion 20-50mcg/min.

INOTROPES GIVEN BY INFUSION

Adrenaline is the most commonly available inotrope, and in many cases the most appropriate drug to

maintain blood pressure. When other inotropes are available, some may offer advantages in certain

situations. The inotropes listed below are only given by infusion unless a bolus dose is stated. They

are mostly very short acting, their effects lasting from a few seconds to one or two minutes and

should be given via a central line (except for aminophylline and salbutamol) via an infusion controller. The

patient must be closely monitored, particularly the ECG and blood pressure. Tachycardia,

arrhythmias, and hypertension or hypotension are side effects of these drugs. Although called inotropes

some of these drugs also have vasoconstrictor properties.

NORADRENALINE

Acts mainly on α1 receptors with few effects on β, D receptors.

Actions Increases blood pressure by vasoconstriction. Less likely to cause tachycardia than

adrenaline.

Indications Septic shock where peripheral vasodilation may be causing hypotension.

Cautions Acts by increasing afterload and therefore not appropriate for use in patients in cardiogenic

shock. Blood supply to kidneys and peripheries may be reduced.

Dose - 1-30mcg/min

• Add 4mg to 250ml 0.9% NaCl or 5%

dextrose to give 16mcg/ml.

Run at 0-112ml/hr

DOPAMINE

Acts on D, β1, β2 and α1 receptors, depending on the dose administered.

Actions Dose dependent. It used to be popular to increase urine output via its effect on the D

receptors in the kidney. However, less commonly used for this purpose as it does not prevent renal failure

and can produce a variety of arrhythmias.

Indications Hypotension.

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Dose 1-2mcg/kg/min - acts on D receptors usually increasing urine output (‘renal dose’)

2-10mcg/kg/min - also acts on β receptors to increase cardiac output (‘inotropic dose’)

> 10mcg/kg/min - additionally has effects on α1 receptors to vasoconstrict. (‘vasoconstructor

dose’)

• Add 3mg/kg (body weight) to 50mls

0.9%NaCl or 5% glucose

• 1ml/hr = 1mcg/kg/min

DOBUTAMINE

Acts on β1 and β2, with minimal action on α1 receptors.

Actions It increases cardiac output and reduces afterload (β2effects on skeletal muscle).

Indications Cardiogenic shock.

Dose 2-30mcg/kg/min

• Add 3mg/kg to 50mls 0.9%NaCl or 5%

glucose

• 1ml/hr = 1mcg/kg/min

DOPEXAMINE

Acts on β2 and D receptors.

Actions It increases cardiac output and reduces afterload. Increases blood supply to the kidneys and

possibly also the gastrointestinal tract.

Dose 0.5-6mcg/kg/min

SALBUTAMOL

Acts on β2 receptors

Actions Relaxes bronchial smooth muscle i.e. bronchodilation, may increase heart rate

Indications Severe acute asthma.

Dose By infusion 5-20mcg/min.Can also be given in bolus form iv in the initial treatment of an attack at a

dose of 5mcg/kg over several minutes.

ISOPRENALINE

Acts on β1 and β2 receptors

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Actions Main action is increased heart rate. Also increased force of contraction, and bronchodilation.

Indications Complete heart block, overdose of beta blocker or severe bradycardia unresponsive to

atropine. Can be used to treat asthma, but less suitable than drugs that act only on β2 receptors e.g.

salbutamol

Dose 0.02-0.2mcg/kg/min by infusion 5-20mcg bolus iv

PHOSPHODIESTERASE INHIBITORS (e.g. AMINOPHYLLINE, ENOXIMONE)

Prevent breakdown of cAMP by enzyme phosphodiesterase: this produces effects at β1 and

β2 receptors.

Actions Inodilation i.e. increased rate and force of contraction, vasodilation in skeletal

muscle. Also bronchodilation.

Indications Aminophylline: asthma, cardiac failure. Enoximone: cardiac failure in patients failing to respond

to dobutamine

Summary

The common causes of hypotension during LSCS under spinal anaesthesia are:

• Vasodilation - treat with fluids and ephedrine

• Aortocaval compression - tilt patient 15 degrees to left

• Bleeding - replace blood loss with intravenous fluids

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REFERENCES

1. Ciliberto CF, Marx GF. Physiological changes associated with pregnancy, Update in Anaesthesia 1998 No.9: 1-6

2. Collins C, Gurung A. Anaesthesia for caesarean section, Update in Anaesthesia 1998

No.9: 7-17

3. Gilmore K. Pharmacology of vasoprocessors and inotropes, Update in Anaesthesia 1999

No.10: 14-17

4. Gupta S. Anaesthesia for nonobstetric surgery during pregnancy in obstetric

anaesthesia, Arya publications, 2004: 79-93

5. Adapted from Circulation, 2005;112:IV-150-IV-153

6. Cephas M. Anaesthesia for a patient with a full stomach, Update in Anaesthesia 1994No.4: 1-5

7. Eldridge J. Monitoring during caesarean section, Update in Anaesthesia 2000 No.11: 37-41

8. Ankcorn C, Casey WF. Spinal anaesthesia – a practical guide, Update in Anaesthesia

1993 No.3: 2-7

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