It Is a Chronic Inflammatory Condition Which Has Three Characteristics

BRONCHIAL ASTHMA

It is a chronic inflammatory condition which has three characteristics

•  Airflow limitation which is usually reversible spontaneously or with treatment

•  Airway hyperresponsiveness to a wide range of stimuli

•  Inflammation of the bronchi

CLASSIFICATION

•  Extrinsic

Implying a definite external cause

•  Intrinsic or cryptogenic

•  No causative agent

ETIOLOGY

Atopy and allergy

Airway hyperactivity

Precipitating Factors

Occupational sensitizers

Non specific factors

•  Cold air and exercise

•  Atmospheric pollution and irritant dusts, vapors and fumes

•  Diet

•  Emotion

•  Drugs

PATHOGENESIS

Mast cells

Epithelium

Basement Membrane

Nerves

Macrophages and lymphocytes

Eosinophils

Mediators - LTD4, Thromboxanes

LTB4, PAF

CLINICAL FEATURES

Wheezing

Episodic shortness of breath

Cough

INVESTIGATIONS

No single satisfactory diagnostic test for all asthmatic patients

•  Lung function test

•  Peak flow charts

•  Exercise test

•  Histamine or methacholine bronchial provocation test

•  Trial of corticosteroids

•  Blood and sputum test (Eosinophils > 0.4*109/L)

•  Chest X-ray

•  Skin tests

•  Allergen provocation tests

MANAGEMENT

Goals

•  To abolish symptoms

•  To restore normal or best possible long-term airway function

•  To reduce the risk of severe attacks

•  To enable normal growth to occur in children

•  To minimize absence from school or employment

This Involves

•  Patient and family participation

•  Avoidance of identified causes where possible

•  Use of the lowest effective doses of convenient medications to minimize short term and long term side effects

CONTROL OF EXTRINSIC FACTORS

•  House dust mite

•  Pets

•  Moulds

•  Certain food stiff (Peanuts etc)

•  Drugs e.g Aspirin, Beta-Blockers

•  Active and passive smoking

•  Preservatives and colouring materials e.g tartrazine

DRUG TREATMENT

B2 adrenoceptor agonist

Anticholinergic bronchodilator

Antiinflammatory drugs

● Sodium cromoglycate

● Nedocromil sodium

Inhaled corticosteroid

Oral Corticosteroids

Antibiotics

Leukotriene receptor antagonists

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MANAGEMENT OF SEVERE ASTHMA

Status Asthmaticus

•  Inability to complete a sentence in one breath

•  Respiratory rate >25 breaths per minute

•  Tachycardia >110 beats min-1

•  PEFR <50% of predicted normal or best

Treatment

•  Oxygen 40-60%

•  Nebulized salbutamol 5mg or terbutaline 10mg

•  Hydrocortisone sodium succinate 200mg IV

•  Nebulized Ipratropium bromide 0.5mg

•  Arterial blood gases

•  Chest X-ray to exclude pneumothorax