Airway Disorders and Asthma
Core concepts
Asthma is chronic airway inflammation with variable expiratory airflow limitation, often atopic. Diagnosis requires compatible symptoms plus documented variability or reversibility; spirometry is preferred when the child is old enough. Severity is assessed before treatment, while control is assessed on treatment. Inhaled corticosteroids are the cornerstone. In children 6–11 years, increasing the inhaled corticosteroid dose is generally preferred before adding a long-acting beta-agonist; montelukast may be considered but carries neuropsychiatric warnings. Acute severe asthma is treated with oxygen, repeated short-acting beta-agonist, ipratropium, early systemic corticosteroids, and magnesium for severe cases. Watch for a silent chest, exhaustion, altered consciousness, and rising carbon dioxide.
Airway disorders have characteristic sounds. Laryngomalacia causes inspiratory stridor that is worse supine and during feeding and is usually self-limited. Tracheomalacia causes expiratory or biphasic symptoms. Subglottic stenosis produces biphasic stridor. A foreign body causes sudden onset, unilateral wheeze, or asymmetric breath sounds. Vocal cord dysfunction can mimic asthma with inspiratory stridor and normal spirometry between episodes.
Traps
Do not label every wheeze as asthma. Missing a foreign body is dangerous. Long-acting beta-agonists are not first-line in young children. A single bronchodilator response in a wheezy child does not by itself prove asthma. Normal oxygen saturation does not exclude severe obstruction.
Worked example and rule of thumb
A 3-year-old with sudden cough and unilateral wheeze after eating peanuts needs urgent airway evaluation, not an asthma step-up. Rule of thumb: inspiratory stridor suggests laryngeal disease, expiratory wheeze suggests lower airway disease, and biphasic stridor suggests fixed or subglottic obstruction.