Asthma — Pathophysiology & Management

Asthma and COPD both cause airflow obstruction, but only one is fully reversible — and that reversibility drives every management decision you'll see on the NCLEX.

Asthma is a chronic inflammatory disorder of the airways characterized by three reversible processes: bronchospasm, mucosal edema, and excessive mucus production. Triggers — allergens, exercise, cold air, respiratory infections, stress — activate mast cells and eosinophils, releasing histamine and leukotrienes that cause smooth muscle constriction and inflammation. This is the key: the obstruction is episodic and reversible, confirmed by an improvement of ≥12% in FEV1 after bronchodilator use on spirometry. During an acute exacerbation, the client presents with wheezing, dyspnea, chest tightness, and a prolonged expiratory phase. Peak expiratory flow (PEF) monitoring guides severity: green zone (80–100% personal best) means well-controlled, yellow (50–79%) signals caution requiring rescue medication, red (<50%) is a medical emergency. Management follows a stepwise approach — identify and avoid triggers, use an asthma action plan, and escalate or de-escalate therapy based on symptom control. The cornerstone of long-term control is inhaled corticosteroids (ICS), while short-acting beta₂-agonists (SABAs) serve as rescue therapy. Status asthmaticus is a life-threatening exacerbation unresponsive to initial bronchodilator therapy requiring emergency intervention including continuous nebulization, IV corticosteroids, and possible intubation.

Key Distinctions

Don't confuse asthma's reversible obstruction with COPD's irreversible obstruction — reversibility on spirometry is the diagnostic divider. Students mix up the asthma PEF zones: red is below 50%, not below 80%. A silent chest during an asthma attack is NOT improvement — it signals critically reduced airflow and imminent respiratory failure, the opposite of what students assume.

Clinical Pearl

Wheezing that suddenly stops during an asthma attack means air is no longer moving. No wheeze in a distressed client is worse than loud wheezing — escalate immediately.