Sažetak
It is well-known that one may increase the maximal duration of apneic diving by performing several attempts in ad-vance. It is also suggested that the spleen contracts in apneic diving, delivering much of its blood content to active circulation. We hypothesized that the spleen empties continuously throughout the first apnea and does not recover in the short period between the next attempt. If so, the second and following apneas would be in advantage over the first one in having larger circulating red blood cell pool at the onset of apnea. In order to test this hypothesis, 10 trained apnea divers, 10 intact and 7 splenectomized untrained persons repeated five maximal apneas (A1-A5) with face immersion in cold water, with two minutes interposed between successive attempts. Ultrasonic monitoring of the spleen and noninvasive cardiopulmonary measurements were performed be-fore, between apneas and at times 0, 10, 20, 40, and 60 minutes after the last apnea. In serial apneas the spleen empties steadily throughout the first attempt and does not recover in the short period be-tween successive attempts. This could contribute to the well-known prolongation of duration of successive, briefly repeated apnea attempts.
