Lung volumes and alveolar gases during actual dives were studied in the Korean diving women, or ama. These women dive without assistance. Average descent and ascent velocities are 0.6 m/sec. Maximal depth and duration of dive observed were 17 m and 82 sec, respectively. However, typical sustained diving activity is to a depth of 5 m for 30 sec, averaging 60 dives/hr. This diving pattern is compared with the assisted dives of the Japanese ama lasting 60 sec and reaching a depth of about 20 m. Prior to diving the lung is filled to 85% of vital capacity. About 700 ml of this gas are lost upon return to the surface. A slight hyperventilation before dive reduces the Pco2 to 28. At the bottom the fractional composition of O2 as well as CO2 is less than before dive indicating that both gases are removed by the circulation. The compression of the gases accounts for the reversal of CO2 transport. Upon return to the surface CO2 leaves the blood and reaches normal values while the O2 is very low. At the bottom O2 pressure is high due to compression but falls rapidly upon ascent. The detailed pattern of gas exchange is discussed. Submitted on September 28, 1962
Various respiratory functions were determined in 20 ama (diving women) as well as in an equal number of nondivers (control group.) The vital capacity was significantly larger in the ama than in the control; this is entirely due to the higher inspiratory capacity in the former group. Neither the residual volume (RV) nor the expiratory reserve volume showed any difference between the two groups. Hence, the RV/TLC ratio tended to be lower in the ama. MBC was considerably higher in the ama. The maximal inspiratory pressure for any given lung volume was significantly higher in the ama, while the maximal expiratory pressure was not different between the two groups. The resting alveolar gas composition is not different from that of the control. The ventilatory responses to breathing 3% and 5% CO2 in O2, as well as the ventilatory responses to breathing 8.5% O2 in N2, were measured and are discussed. It is suggested that some of these differences in pulmonary function between the ama and control group represent long-term adaptations of the divers acquired by engaging daily in diving operations. Submitted on September 28, 1962
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