Palada Ivan, Obad Ante, Bakovic Darija, Valic Zoran, Ivancev Vladimir, Dujic Zeljko
Department of Physiology, University of Split School of Medicine, Soltanska 2, 21000 Split, Croatia.
Respir Physiol Neurobiol. 2007 Aug 1;157(2-3):374-81. doi: 10.1016/j.resp.2007.02.002. Epub 2007 Feb 8.
The effects of maximal apneas on cerebral and brachial blood flow and oxygenation are unknown in humans. Middle cerebral artery blood velocity (MCAV), cerebral and muscle oxygenation (Sc(O2) and Sm(O2)) and brachial blood flow (BBF) were measured during apneas in breath-hold divers (BHD) and non-divers (ND). Brain oxyhemoglobin (O(2)Hb) was maintained in both groups until the end of apnea, whereas deoxyhemoglobin increased more in BHD. Therefore, Sc(O2) decreased more in BHD due to longer apnea duration and smaller initial MCAV increase. MCAV increased significantly more in BHD versus ND at the end of apnea. Cerebral desaturation for approximately 13% occurred at the end of apnea in BHD despite increased cerebral oxygen delivery for approximately 50%. Larger reduction in muscle O(2)Hb was found in BHD, with similar peripheral vasoconstriction. These data indicate that BHD have decreased Sc(O2) at the end of breath-hold despite large increases in MCAV. This is partly due delayed initial cerebral vasodilation. This study provides further evidence for the oxygen-conserving effect in elite divers.
最大呼吸暂停对人体脑血流和肱血流及氧合的影响尚不清楚。在屏气潜水员（BHD）和非潜水员（ND）呼吸暂停期间，测量了大脑中动脉血流速度（MCAV）、脑和肌肉氧合（Sc(O2)和Sm(O2)）以及肱血流（BBF）。两组在呼吸暂停结束前脑氧合血红蛋白（O(2)Hb）均保持稳定，而脱氧血红蛋白在BHD中增加更多。因此，由于呼吸暂停持续时间更长且初始MCAV增加较小，BHD中Sc(O2)下降更多。呼吸暂停结束时，BHD的MCAV显著高于ND。尽管脑氧输送增加了约50%，但BHD在呼吸暂停结束时仍出现了约13%的脑去饱和。在BHD中发现肌肉O(2)Hb的下降幅度更大，外周血管收缩情况相似。这些数据表明，尽管MCAV大幅增加，但BHD在屏气结束时Sc(O2)仍下降。这部分是由于初始脑血管扩张延迟。本研究为精英潜水员的氧保存效应提供了进一步证据。
