Eucapnic voluntary hyperpnea
Eucapnic voluntary hyperpnea (EVH) is widely considered the gold-standard test for diagnosing exercise-induced asthma (EIA).
EVH challenge protocol
The EVH challenge is a 6-min test during which the athlete breathes a cold, dry gas at very high ventilation rates. Airway function following the test is compared against normal resting (baseline) airway funtion.
During an EVH test athletes need to maintain a breathing rate of 80% of their maximal voluntary ventilation (MVV). This target ventilation is predicted from the volume of air exhaled in the first second (FEV1) of a forced expiratory manœuvre.
Airway function
FEV1 is the most frequently used measure of airway obstruction and bronchoconstriction. During the EVH challenge a drop in the post-test FEV1 (compared with baseline values) of more than 10% is considered a positive diagnosis of EIA.
