Exercise-Induced Bronchoconstriction and Compressed Air Breathing with SCUBA

Abstract

1561 Cool, dry air is a potent stimulus for bronchoconstriction in those individuals susceptible. Thus, diving with compressed air potentially increases the risk of airway narrowing in those with exercise-induced bronchoconstriction (EIB). However, this has not been investigated. PURPOSE: The purpose of this study was to determine the influence of breathing compressed air via self-contained underwater breathing apparatus (SCUBA) regulators while exercising on the severity of EIB. METHODS: Ten non-asthmatic Controls and ten subjects with diagnosed EIB volunteered. Pre and post exercise pulmonary function was measured by spirometry. Subjects performed a treadmill run for 5 minutes at approximately 80% of their age-predicted maximal heart rate. On one occasion they breathed ambient air and on another they breathed compressed air via SCUBA regulators. Oral breathing was forced via the use of a nose clip. Forced expiratory volume in 1 second (FEV1) was used to determine changes in pulmonary airway function. RESULTS: Both groups had normal pulmonary function prior to the exercise. Control subjects had no change in pulmonary function after exercise on either occasion. EIB subjects demonstrated an average post-exercise decrease in FEV1 of about 15% over 15 minutes post exercise while breathing ambient air. While breathing compressed air via SCUBA, EIB subject's pulmonary function worsened significantly by about 61% over the 15 minutes post exercise, to a 24% decrease in post-exercise FEV1. CONCLUSIONS: This study demonstrated that compressed air breathing via SCUBA increased the severity of EIB in EIB subjects. The results have implications for those EIB individuals wishing to dive. Supported by the Professional Association of Diving Instructors (PADI) foundation.