Asthma: Onset, Pathophysiology, and Triggers

Asthma is a chronic inflammatory airway disease with variable airflow obstruction and bronchial hyperresponsiveness. It is not congenital; onset can occur at any age, though childhood diagnosis is common.

Key Features

• Inflammation: eosinophilic (Th2), neutrophilic, or paucigranulocytic.
• Airway remodeling (subepithelial fibrosis, smooth muscle hypertrophy) with chronicity.
• Triggers: allergens, viruses, exercise, cold air, irritants, stress, NSAIDs (in aspirin‑exacerbated respiratory disease).

Diagnosis

• Spirometry with bronchodilator reversibility (FEV₁ increase ≥12% + 200 mL).
• Bronchial challenge (methacholine, mannitol) if spirometry normal.
• FeNO (eosinophilic inflammation marker).

Management

Stepwise: ICS‑formoterol as reliever (MART) or SABA + maintenance ICS/LTS/LAMA. Biologics (anti‑IgE, IL‑5/5R, IL‑4Rα, TSLP) for severe eosinophilic/Type 2 asthma.