Practical Physiology - -Erythrocyte Erythrocyte

Sedimentation RateSedimentation Rate..

- -Bleeding timeBleeding time..

- -Clotting timeClotting time..

Erythrocyte Sedimentation Rate (ESR) (Westergren method)

Procedure:Under aseptic conditions withdraw (1.6 ml ) of blood from a vein and mix with (0.4 ml) of 3.8% sodium citrate as anticoagulant (4:1), suck this blood into a Westergren tube, adjust the top level at (0 mm) mark. Wipe the blood off its tip and set the tube in a vertical position in the Westergren rack. RBCs settle down leaving a column of clear plasma on the top. After exact one hour read the upper level of the RBC column. The result is expressed in mm/1mm/1stst hr hr.

(ESR) (Westergren method) Normal ranges of ESR:Male 0 –15 mm/1st hr.Female 0 –20 mm/1st hr.

ESR estimation also has a prognostic value and

a fall in ESR after treatment indicates good prognosis.

PHYSIOLOGICAL BASIS OF PHYSIOLOGICAL BASIS OF ESRESR

Determine ESRDetermine ESR

ESRESRNormal  Values:

Males: 3-9 mm 1st hourFemales: 5-12 mm 1st hour.

Factors affecting ESRIncreased ESR in

inflammation, infections, (increased globulins) & Bone fractures & malignancy (increased plasma fibrinogen).Decreased ESR in: may be Polycythemia.

Clinical significance of Clinical significance of ESRESR

The changes of ESR are, not diagnostic of any specific disease but it is of a prognostic value

(If the patient is improving the ESR tends to fall. If the patient’s condition is getting worse the ESR

tends to rise.)

Bleeding time (Dukeś method)

Procedure:1. Clean a finger ball with spirit and with a

sterile lancet give at least 2 mm deep prick. Note the time.

2. Every 15 sec. blot off the drop of blood by a filter paper until no more blood appears on the puncture site. Note the time at which the bleeding has stopped.

Bleeding time (illustration) Cont…..

Bleeding time test(Duke’s method)

B.T = = ? min.no. of blots

4

Every 15 sec.

-Normal bleeding time (B.T) = 1 – 4 min.-Normal bleeding time (B.T) = 1 – 4 min.

Bleeding time (Dukeś method) Cont…..

Estimation of bleeding time is not a reliable test, because the results of this test would vary depending on the site and depth of the puncture. Moreover it is shortened in cold weather, due to capillary constriction, and reverse is the case in hot weather.-It is especially prolonged by lack of platelets (Thrombocytopaenia ).

Events in haemostasis (Arrest of bleeding): 1- Vasoconstriction. 1- Vasoconstriction. 2- Platelet aggregation. 2- Platelet aggregation. 3-3- Blood coagulation. Blood coagulation.

Bleeding timeBleeding timeClinical Significance:

It is usually significantly prolonged in the case of congenital or acquired platelet defects.Defect in platelets ;

a) Thrombocytopenic purpura; more common.It is due to low platelet count below 50.000/cmm.

May be due to decreased production or increased destruction

b) Thrombocytopathic purpura; less commonIt is due to defect in platelet function (count is normal).

in a & b, bleeding time normally (1-4 min) is prolonged.

Clotting time (capillary tube method)

Procedure:1. Clean the finger with spirit and give a deep

prick with a sterile lancet, squeeze the finger to obtain a large drop of blood. Note the time (T1).

2. Fill in two plain capillary tubes with blood. 3. After (1/2 min.), start breaking small pieces of

one capillary tube every 30 sec. until a fibrin thread is seen in the interval between the 2 broken equivocal ends.

4.The interval between T1 and T2 is the clotting time.

Clotting time (illustration)

Fibrin thread

Clotting time test (capillary tube method).

-Normal Clotting time (C.T) = 5 – 8 min .-It is increased in haemophilia.

T2

1 2 3 4 5 6 7 8

CLOTTING time

No= 4-8 minutes.Causes of prolonged clotting timea) Liver disease

It leads to failure of formation of Clotting factors by the liver cells.

b) HaemophiliaHaeomophilia is characterized by bleeding after trauma.