Field study of ventilation in volunteer scuba divers during head-out immersion.

Seven subjects had spirometric studies during head-out immersion before and after working at depth in coral research. Under the variable environmental conditions of a field study the seven subjects demonstrated changes in the spirometric variables consistent with those found in wet laboratories. Exercise at depth did not change the variables from preexercise levels. This suggests either that the body reestablishes preexercise head-out immersion equilibrium rapidly or that subtle changes were beyond the sensitivity of the instrument. On head-out immersion, one subject with abnormal control values of FEV1/FVC% and FEF25-75 had a rise rather than a fall in these values, which was the opposite of that of the other six subjects and the expected result.