Features of exercise-induced asthma:
(1) self-limited syndrome of cough, wheezing, dyspnea, chest tightness, skin rash (urticaria), chest pain, abdominal pain, nausea or vomiting or other respiratory symptoms
(2) triggered by exercise. This may include continuous running exercise for 5-8 minutes in either cold or dry air, bicycling or use of treadmill.
Test Protocol:
(1) Consent is obtained.
(2) The patient is screened by interview or questionnaire for (a) a history of being diagnosed as having allergic rhinitis, asthma or exercise-induced asthma, (b) symptoms of asthma, especially associated with exercise.
(3) Measure peak expiratory air flow in liters/second using a peak flow meter. Record the person's resting pulse.
(4) Exercise for 5-8 minutes by continuous running.
(5) Persons unable to complete the test should be allowed to stop at any point but should be encouraged to complete the challenge if possible.
(6) The pulse on stopping is taken and should be about double the resting rate.
(7) Measure peak expiratory air flow upon completion of exercise. Continue to monitor for at least 5-8 minutes after running completed
Interpretation:
• Test is positive if there is a >= 15% reduction in peak flow following 5-8 minutes of continuous running exercise.
• A patient with a "positive" test result should be referred to their family physician for further evaluation. The definitive diagnosis can be made by either (a) reproducible findings on spirometry testing before and after bronchodilators, and/or (b) exercise challenge with monitoring for 30 minutes after completion of the challenge.
Performance of test:
• Sensitive (94-95% vs questionnaire) with high negative predictive value (98%) but has poor predictive value (39-44%).
• False positives relatively common. Other conditions having a positive response include: poor physical conditioning, vocal cord dysfunction
• False negatives occur (up to 20%). Some patients require monitoring for up to 30 minutes after the exercise stimulus. Some patients may have the asthma triggered by food or other stimulus in conjunction with the exercise. Some patients may require a longer exercise period to trigger bronchospasm.
