Exercise-induced bronchoconstriction — structured clinical encounter

Station brief (candidate)

You are the paediatric registrar in a general clinic. A 10-year-old girl is referred because she coughs and wheezes when she plays sport and has begun to avoid it. Her symptoms start a few minutes into a game, are worst just after she stops, and settle with rest over about half an hour. She has eczema and coughs at night in winter. Her chest is clear today. The team asks you to confirm the diagnosis, control any underlying asthma, build the exercise plan, and counsel the family. You have 12 minutes with the family and 5 minutes for examiner discussion. [3]

Information available on request

• Cough, wheeze and chest tightness a few minutes into sport, worst after stopping, settling with rest over thirty minutes; worse in cold weather. [3]
• Personal atopy (eczema) and a nocturnal winter cough; no chest pain, palpitations or syncope with exercise. [3]
• She has started sitting out of physical education and team sport because of the symptoms. [12]
• Examination: normal chest between episodes; no clubbing, no cardiac murmur; growth on the 50th centile; eczema in the flexures. [3]
• Investigations (on request): normal resting spirometry; a standardised exercise challenge shows FEV1 falling 22 percent from baseline, recovering within 40 minutes. [10]

Tasks

1. Give the diagnosis and the features that support it, and explain how you have confirmed it objectively. [3] [10]
2. Classify the diagnosis by clinical context and by severity. [3]
3. Build the management plan, naming the most important first step, the non-drug measures, and the role of a pre-exercise reliever. [12] [5]
4. Counsel the family, who ask whether she should give up sport. [12]
5. State the mimic you were careful to exclude and how it would have differed. [3]

Expected approach (examiner notes)

1. The diagnosis is exercise-induced bronchoconstriction, most likely as part of asthma. It is supported by the classic after-exercise pattern (symptoms a few minutes into effort, worst after stopping, settling with rest), the cold-weather worsening, the personal atopy and nocturnal winter cough suggesting underlying asthma, and the normal chest between episodes. It is confirmed objectively by the standardised exercise challenge showing a fall in FEV1 of 22 percent from baseline — well above the ten-percent diagnostic threshold — with recovery within 40 minutes; the normal resting spirometry does not exclude it. [3] [10]

2. By clinical context this is exercise-induced bronchoconstriction occurring within asthma, given the interval features (nocturnal cough, atopy), rather than isolated disease. By severity the 22 percent maximum fall in FEV1 places it in the moderate range (25 to under 50 percent is moderate; 10 to under 25 percent is mild), sitting at the upper end of mild toward moderate, which guides how firmly to treat and supervise. [3]

3. The most important first step is to control the underlying asthma with a regular inhaled corticosteroid, because her exercise symptoms signal inadequate control; I would confirm adherence and inhaler technique. Non-drug measures for every child are a warm-up before exercise (which induces a protective refractory period), warming inspired air with a scarf in the cold, and avoiding the worst conditions. A pre-exercise short-acting beta-agonist taken ten to fifteen minutes before sport covers breakthrough symptoms, but daily use should be avoided because it causes tolerance; persistent symptoms would prompt a controller step-up or add-on therapy. [12] [5]

4. I would counsel the family firmly that she should not give up sport: the explicit goal of treatment is full, unrestricted participation, and with the underlying asthma controlled, a warm-up and a pre-exercise reliever, the overwhelming majority of children exercise and compete normally. Exercise is beneficial and achievable, and avoiding it would harm her fitness, weight, participation and confidence. I would provide a written plan and arrange review. [12]

5. The mimic I was careful to exclude is inducible laryngeal obstruction (vocal cord dysfunction). It would have differed by producing inspiratory stridor and throat tightness at peak effort rather than an expiratory wheeze after it, clearing within a minute or two without a bronchodilator, and — decisively — it would have shown no significant fall in FEV1 on the exercise challenge. Her 22 percent fall confirms the airway is the problem. [3]

Examiner probes

• "Why did you challenge her rather than treat on the history alone?" Because symptoms are unreliable and both over- and under-diagnosis are common; the objective fall in FEV1 confirms the diagnosis, grades severity, and excludes the mimics. [10]
• "She uses her reliever every day before sport and it is working. Is that fine?" No — daily short-acting beta-agonist use causes tolerance and reduced bronchoprotection, and marks poor control; the correct response is to step up the controller, not to continue daily reliever. [5]
• "What one feature would have made you look for a cardiac cause instead?" Exertional chest pain, palpitations or syncope, which never belong to the airway and demand a different workup. [3]