Exercise-induced wheezing

Specialty: Respiratory.

• exercise-induced bronchospasm
• wheezing due to physical exertion

Why it occurs

• Bronchial asthma with suboptimal control (hyperventilation during exercise causes cooling and dehydration of the airway mucosa, which triggers the release of inflammatory mediators by mast cells and the subsequent contraction of bronchial smooth muscle)
• Isolated exercise-induced bronchospasm (in patients without baseline clinical asthma but with transient bronchial hyperreactivity associated with environmental conditions such as cold and dry air)
• Vocal cord dysfunction or paradoxical laryngeal movement during physical effort (which acoustically imitates bronchial wheezing)
• Persistent post-infectious bronchial hyperreactivity (after mycoplasma pneumonia or severe viral bronchitis)
• Subclinical left heart failure ("cardiac asthma" triggered by increased pulmonary capillary pressure during exercise).

Initial workup

Basal forced spirometry with bronchodilator test; Bronchial provocation test with protocolized exercise (treadmill or cycle ergometer) measuring the forced expiratory volume in the first second (FEV1) before and at intervals of 5, 10, 15 and 30 minutes post-exertion, with a drop in FEV1 greater than or equal to 10% being considered positive; Methacholine challenge test or dry/cold air inhalation.

Standard management

• Salbutamol — 100-200 micrograms inhaled through a spacer chamber 15-30 minutes before starting exercise as a prophylactic measure of choice
• Montelukast — leukotriene receptor antagonist, 10 mg orally once daily in the evening for long-term control of exercise-induced hyperresponsiveness
• Budesonide/Formoterol (inhaled as needed before exercise in selected regimens).