EFFECTS OF A SINGLE SATURATION DIVE ON LUNG-FUNCTION AND EXORCISE PERFORMANCE

We studied the effects of an experimental saturation dive to 360 and 4 50 m in a simulation chamber on spirometric lung function, diffusing c apacity, pulmonary compliance, and exercise performance in eight profe ssional divers (age 22-40 years). To assess intraindividual variabilit y, all parameters were measured on 2 days before and on 2 consecutive days immediately after the dive. For the group as a whole there was a significant increase in vital capacity and alveolar volume, and a decr ease in Krogh factor and specific compliance (P < 0.01). These changes were reduced on the 2nd day after the dive. All subjects showed lower ed exercise performance after the dive. Arterial pressure of oxygen an d ventilation during exercise increased (P < 0.01), whereas arterial p ressure of carbon dioxide, oxygen uptake, and anaerobic threshold decr eased (P < 0.01). Exercise parameters showed only a slight trend towar ds pre-dive values on the 2nd day after a dive. The individual analysi s revealed that after the dive two subjects showed a marked decrease i n diffusing capacity and a more than average decrease in Krogh factor (TL(CO)/V-A). One of them had signs of mild decompression sickness and the other, signs of preexisting obstructive airways disease. Our data are compatible with the hypothesis that the effects of a single deep saturation dive on pulmonary function and exercise performance are the results of counteracting mechanisms. We suggest that lung volumes inc rease due to the enhanced work of breathing during a deep saturation d ive and that these changes could mask an impairment in gas exchange. F urthermore, a saturation dive can induce an apparent deterioration of pulmonary function.