Karen Conyers, BSRT, RRT

AIRWAY CLEARANCE

Airway Clearance

Pulmonary Physiology and Development

Impaired Airway Clearance

Airway Clearance Techniques

Therapy Adjuncts

PULMONARY PHYSIOLOGY

AND DEVELOPMENT

Birth Respiratory Function

– Terminal respiratory unit not fully developed– Respiratory function performed by alveolar-capillary bed

Airways– Little smooth muscle– Small airway diameter– Increased airway resistance

Lung compliance– Incomplete elastic recoil– Decreased lung compliance

Age 2 Months Alveoli

– 24 million alveoli present – Alveoli small but fully developed– Ability to form new alveoli

Respiratory muscles– Underdeveloped accessory muscles– Diaphragm is primary muscle of respiration

Response to increased ventilatory demands– Respiratory rate increases, not tidal volume

Ages 3 to 9 Months

Increasing strength– Baby learns to hold head up, reach for things– Upper body strength develops, including accessory

muscles for respiration Changes in respiratory function

– Learns to sit up: rib cage lengthens – Greater chest excursion– Increased tidal volume

Age 4 Years

Lung development– Development of pre-acinar

bronchioles and collateral ventilation (pores of Kohn)

– Development of airway smooth muscle

Age 8 Years

Continued lung development– Alveolar development complete – Alveolar size increases– Total lung volume increases – 300 million alveoli (increased from 24 million

at age 2 months)

Adult Lung

Gradual loss of volume Loss of elasticity

– Decreasing compliance

Environmental effects– Smoking– Air pollution– Occupational hazards

Disease effects

Factors Affecting Airflow

Airway resistance

Turbulent airflow

Airway obstruction

Normal Airway Resistance Decreasing cross-sectional area from acinus to

trachea causes increased resistance, as airflow moves from small to large airways.

Cross-sectional areas:– trachea diameter 2 cm– 4th generation bronchi 20 cm– bronchioles 80 cm– acinus cross-section 400 cm

Greatest airway resistance in large airways; laminar

airflow in small airways

Airway Obstruction

Increased airway resistance– Bronchospasm– Inflammation

Hypersecretion of mucus– Acute process– Chronic disorder

Mucus

Mucus produced by goblet cells in airway

Chronic airway irritation increased numbers

of goblet cells larger quantities of mucus

Cilia move together in coordinated fashion to move

mucus up airways

IMPAIRED

AIRWAY CLEARANCE

Impaired Airway Clearance: Factors

Ineffective mucociliary clearance Excessive secretions Thick secretions Ineffective cough Restrictive lung disease Immobility / inadequate exercise Dysphagia / aspiration / gastroesophageal reflux

Results of Impaired Airway Clearance

Airway obstruction

Mucus plugging

Atelectasis

Impaired gas exchange

Infection

Inflammation

A Vicious Cycle

Entering the Cycle

ASPIRATION

ASTHMA

ASPERGILLOSIS

CYSTICFIBROSISGASTRO-

ESOPHAGEALREFLUX

PRIMARYCILIARY

DYSKINESIA

NEURO-MUSCULARWEAKNESS

AIRWAY CLEARANCE

TECHNIQUES

Airway Clearance Techniques

Goals

Conventional Methods

Newer Therapies

Therapy Adjuncts

Goals

Interrupt cycle of lung tissue destruction

Decrease infection and illness

Improve quality of life

Conventional methods

Cough

Chest Physiotherapy

Exercise

Cough

Natural response

Only partially effective

Frequent coughing leads to “floppy” airways

May be suppressed by patient

Chest Physiotherapy (CPT)

Can be used with infants Requires caregiver participation Technique dependent Time consuming Physically demanding Requires patient tolerance Effectiveness debated

Exercise

Recommended for most patients Pulmonary rehabilitation expectation Training

– Ability to exercise related more to muscle mass than to pulmonary function

– Improves oxygen uptake by muscle cells

Many patients limited by physical disability

Newer Therapies

PEP valve Flutter In-Exsufflator HFCWO (Vest) Intrapulmonary percussive ventilation (IPV) Cornet PercussiveTech HF

PEP valve

Positive Expiratory Pressure Action: splints airways during exhalation Can be used with aerosolized medications Technique dependent Portable Time required: 10 - 15 minutes

Flutter

Action: loosens mucus through expiratory oscillation; positive expiratory pressure splints airways

Used independently Technique dependent Portable May not be effective at low airflows Time required: 10 - 15 minutes

In-Exsufflator

Action: creates mechanical “cough” through the use of high flows at positive and negative pressures

Positive/negative pressures up to 60 cm of water Used independently or with caregiver assistance Technique independent Portable

ABI Vest (HFCWO) Action: applies High Frequency Chest Wall Oscillation

to entire thorax; moves mucus from peripheral to central airways

Used independently or with minimal caregiver supervision

May be used with aerosolized medications Technique independent Portable Time required: 15-30 minutes

Intrapulmonary Percussive Ventilation (IPV)

Action: “percussion” on inspiration, passive expiration; dense, small particle aerosol

Used independently or with caregiver supervision

Used with aerosolized meds Technique dependent May not be well tolerated by patient Time required: 20 minutes

Other devices

Cornet– Similar to action of Flutter– Lower cost, disposable

PercussiveTech HF– Hand-held device used with aerosol meds– Similar to action of IPV– Requires 50 PSI gas source

European / Canadian Techniques

Huff cough (forced expiratory technique)

Active Cycle of Breathing Technique (ACBT)

Autogenic Drainage

Forced Expiratory Technique

“Huff” cough– Three second breath hold – Open glottis– Prevents airway collapse– Effective technique for “floppy” airways– Easy to learn

Active Cycle of Breathing Technique

Three steps: – Breathing control– Thoracic expansion / breath hold– Forced expiratory technique

May be performed independently Easily tolerated

Autogenic Drainage

Three phases– Unsticking– Collecting– Evacuating

May be performed independently Harder to teach and to learn than other techniques May be difficult for very sick patients to perform

Autogenic Drainage

NormalBreathing

CompleteExhalation

VT

RV

ERV

IRV

Cough

UNSTICKING COLLECTING EVACUATING

THERAPY

ADJUNCTS

Therapy Adjuncts

Antibiotics

Bronchodilators

Anti-inflammatory drugs

Mucolytics

Nutrition

Antibiotics

Oral Intravenous Nebulized

– Aminoglycosides: P. aeruginosa Gentamycin: 40-80 mg Tobramycin: 40-120 mg Tobi: 300 mg per dose: high dose inhibits mutation of

P. aeruginosa in lung

Bronchodilators

Hyperreactive airways common in many

pulmonary conditions

Albuterol, Atrovent

MDI or nebulized

Administered prior to other therapies

Mucolytics

Mucomyst (acetylcysteine)– Breaks disulfide bonds– Airway irritant

Pulmozyme (dornase alfa or DNase)– Targets extracellular DNA in sputum– Specifically developed for cystic fibrosis

Hypertonic saline– Sputum induction– Australian studies

Anti-inflammatory Drugs

Inhaled steroids via metered dose inhaler

Oral or IV prednisone

High-dose ibuprofen (cystic fibrosis)

Nutrition

Connection between nutrition and lung function!

Worsening lung function Worsening lung function increased work of

breathing & frequent coughing increased

caloric need

Increasing dyspnea decreased caloric intake

malnutrition decreased ability to fight

infection worsening lung functionworsening lung function

Interrupting the Vicious Cycle

ANTIBIOTICSANTI -

INFLAMMATORIES

AIRWAYCLEARANCETECHNIQUES

MUCOLYTICS

BRONCHODILATORS

NUTRITION