Andersson J P A, Evaggelidis L
Department of Cell and Organism Biology, Lund University, Lund, Sweden.
Scand J Med Sci Sports. 2009 Feb;19(1):87-91. doi: 10.1111/j.1600-0838.2008.00777.x. Epub 2008 Feb 21.
Competitive breath-hold divers try to achieve maximum times, depths, or distances underwater, thereby risking hypoxic syncope. In the present study, the cardiorespiratory responses to dynamic apnea (simultaneously initiated apneas and dynamic leg exercise) were investigated in 10 breath-hold divers. The divers performed 60 s dynamic apneas with the face in air (A) or face immersed in cold water (AFI). During apneas, the arterial oxygen saturation was reduced (A: -10%), but to a lesser extent during AFI (-6%, P<0.01), reaching a nadir 10-15 s post-apnea. Also, changes in end-tidal O(2) and CO(2) pressures (P(et)O(2)/P(et)CO(2)) were smaller during AFI than A (DeltaP(et)O(2): 8.2 vs 8.7 kPa, P<0.01; DeltaP(et)CO(2): 3.1 vs 3.2 kPa, P<0.05). The heart rate was lower during AFI than A (66 vs 78 bpm, P<0.01), reflecting an augmented diving response during AFI. The maximum safe breath-hold time under the conditions of the present study was calculated to be 101 and 106 s for A and AFI, respectively, consistent with the dynamic apnea times achieved by world-class apnea divers. It is concluded that the augmented diving response during face immersion apneas is associated with a slower reduction of the pulmonary (and arterial) oxygen store, probably delaying the occurrence of a hypoxic syncope.
竞技屏气潜水者试图在水下达到最长时间、最大深度或最远游距，从而面临低氧性晕厥的风险。在本研究中，对10名屏气潜水者进行了动态屏息（同时开始屏息和腿部动态运动）时的心肺反应研究。潜水者在面部暴露于空气中（A组）或面部浸入冷水中（AFI组）的情况下进行60秒的动态屏息。在屏息过程中，动脉血氧饱和度降低（A组：-10%），但在AFI组降低幅度较小（-6%，P<0.01），在屏息后10 - 15秒达到最低点。此外，AFI组终末潮气O₂和CO₂压力（P（et）O₂/P（et）CO₂）的变化小于A组（ΔP（et）O₂：8.2对8.7 kPa，P<0.01；ΔP（et）CO₂：3.1对3.2 kPa，P<0.05）。AFI组心率低于A组（66对78次/分钟，P<0.01），反映出AFI组潜水反应增强。在本研究条件下，A组和AFI组的最大安全屏息时间分别计算为101秒和106秒，与世界级屏息潜水者达到的动态屏息时间一致。研究得出结论，面部浸入屏息过程中增强的潜水反应与肺（和动脉）氧储备的较慢减少有关，可能会延迟低氧性晕厥的发生。
