Eucapnic Voluntary Hyperventilation Screen for Bronchospasm Risk During a SCUBA Dive

Abstract

Eucapnic Voluntary Hyperventilation (EVH) may be used to duplicate the cold dry air exposure of a SCUBA dive. It should be useful to evaluate the likelihood of bronchospasm in potentially susceptible individuals who wish to dive. A 15 year old female student who sought enrollment in a SCUBA diving class had an undocumented history of wheezing after a respiratory infection in the past, was on no medications presently and had normal pulmonary functions. Using a previously described simplified method, she was given an EVH challenge with a target ventilation of 25 times her FEV1 (62.5% of her estimated Maximum Voluntary Ventilation) for 6 minutes. The applicant had a 24.8% decrease in her FEV1 from baseline at 15 minutes after the challenge and required inhaled bronchodilator to restore her pulmonary function to baseline values. She was informed that she would be at risk of exercise induced bronchospasm triggered by the cold dry air of SCUBA exposure during actual dive conditions. This in turn would create the risk of arterial gas embolism, rupture of lung membranes, mediastinal emphysema or pneumothorax due to the expansion of trapped air upon ascent from depth and, accordingly, she was advised not to SCUBA dive. A simplified method for EVH may be conveniently used to evaluate individuals for the risks attendant to exercise induced bronchospasm triggered by the cold dry air typically ventilated during a SCUBA dive.