Practice recommendations
- Don’t rely on self-reported symptoms to diagnose exercise-induced bronchoconstriction (EIB) (A).
- Indirect testing is the best way to diagnose EIB in patients who do not have underlying asthma (A).
- Short-acting β2-agonists should be first-line management in EIB (A).
Strength of recommendation (SOR)
- Good-quality patient-oriented evidence
- Inconsistent or limited-quality patient-oriented evidence
- Consensus, usual practice, opinion, disease-oriented evidence, case series
Luke, a 16-year-old basketball player, complains that he can’t finish a game without running out of breath. He says things are at their worst when the game is close and when it’s nearing the end. He doesn’t have the problem during practice, or when he is playing other sports. The team physician suggested using an albuterol inhaler half an hour before game time and when he has symptoms, but he gets only minimal relief. Now he has come to you.
His vital signs, lung exam, and cardiac exam are normal. Results of pulmonary function tests with pre- and post-albuterol challenge done a year ago were also normal. Does Luke have exercise-induced bronchoconstriction (EIB)? How can you be sure? And what can you do to help?
Symptoms like Luke’s are common among athletes of all abilities. They may add up to EIB, a condition with an estimated prevalence of 6% to 12% in the general population—or they may not.1 One study showed that only a third of athletes with symptoms or prior diagnosis of EIB had positive objective testing for the condition, and current studies show that reported symptoms are not an accurate guide in athletes like Luke who do not have underlying asthma.2,3 To treat him correctly, you will need to nail down the diagnosis with additional tests.3,4
Shortness of breath that’s worse than expected
EIB can have many different presentations. The most common symptom is cough associated with exercise.3 Other common signs and symptoms include wheezing, chest tightness, and more severe than expected or worsening shortness of breath. More unusual symptoms include a decrease in performance or fatigue out of proportion to workload. Often patients with EIB have other associated medical conditions, such as allergic rhinitis.
Bronchoconstriction usually occurs with maximal or near maximal exertion. Generally, it takes 5 to 8 minutes of exercising at 80% of maximal heart rate to trigger EIB. Classically, the symptoms peak 5 to 10 minutes after exercise begins.5
Rule out cardiac problems. If EIB is the correct diagnosis, the physical exam is usually normal. The importance of the physical exam is to evaluate for other diagnoses with similar presentations. Conditions to rule out include cardiac problems, exercise-induced hyperventilation, upper and lower respiratory infections or abnormalities, exercise-induced laryngeal dysfunction, exercise-induced anaphylaxis, and gastroesophageal reflux disease (GERD). The differential diagnosis for EIB is summarized in TABLE 1.
Test for asthma. Once you have gone through the differential diagnosis and are comfortable that the symptoms are respiratory, the next step should be pulmonary function tests (PFT), pre- and post-albuterol challenge. Findings of obstruction, such as reduced forced expiratory volume in 1 second (FEV1) or increased lung volume, are consistent with a diagnosis of asthma. In that case, no further workup is needed—unless the patient is unresponsive to asthma treatment. In athletes like Luke who do not have asthma and have a normal nonprovocative spirometry, you can move on to either provocative spirometry or empiric treatment.
TABLE 1
Is it EIB, or something else?
| ETIOLOGY | POSSIBLE DIAGNOSES |
|---|---|
| Pulmonary | Exercise-induced hyperventilation (pseudo-asthma syndrome) Restrictive lung disease Cystic fibrosis Upper and lower respiratory infections Foreign body aspiration |
| Cardiac | Coronary artery disease Congenital and acquired heart defects Cardiomyopathy Congestive heart failure |
| Laryngeal | Exercise-induced laryngeal dysfunction Vocal cord dysfunction Laryngeal prolapse Laryngomalacia |
| Gastroesophageal | Gastroesophageal reflux disease |
| Allergic | Exercise-induced anaphylaxis |
| Other | Athlete is out of shape |
| EIB, exercise-induced bronchoconstriction. | |
| Source: Weiler JM, et al. J Allergy Clin Immunol. 2007.4 | |
Perform provocative spirometry
Direct spirometry is commonly done with a methacholine challenge. This test is less sensitive than indirect testing for EIB patients who do not have underlying asthma.
The gold standard for indirect testing is eucapnic voluntary hyperventilation (EVH). Because EVH requires special equipment, however, it may not be an option in your office. The more reasonable choice is exercise challenge testing, which can be done either in your office or in the milieu—the basketball court, for example—where the athlete’s symptoms usually occur. In an exercise challenge, you get a baseline spirometry measurement, have the athlete exercise to 80% to 90% of maximal heart rate, and then repeat spirometry at short intervals after exercise ends. If you do an exercise challenge in the office, you can reduce false-negative results by maintaining an ambient temperature between 68° and 77°F (20°-25°C) with a relative humidity of less than 50%.6,7