Episodic Reversible bronchospasm triggered by external agents.

Eosinophilic inflammation, Mucous gland & smooth muscle hypertrophy.

Attacks last 1- several hours. Responds to bronchodilator & steroid therapy

CO2 should be low in asthma due to prolonged expiration

if increasing, decompensating

Atopic / Intrinsic asthma: commonest - TH2 mediated type 1 IgE hypersensitivity. Family history of allergy /atopy. Genetic predisposition – Mutations in IL 4, 5 & 13 & ADAM genes.

Non-atopic / Extrinsic Asthma: No allergen / no family history. Toxins inducing direct hypersensitivity. Chemicals & Infections.

Drug Induced Asthma: Aspirin

Occupational Asthma: Industrial pollutants.

Exercise induced asthma: Dehydration / heat loss.

Status Asthmaticus: severe persisting attack (days) not responding to therapy. Mucous plugging, air trapping, hyperinflation, Severe hypoxia & Respiratory acidosis. May be fatal.

Demographics

• In kids, males more common than females.
• In adults, Females more common than males.

Pathophysiology