Role of the altitude level on cerebral autoregulation in residents at high altitude
Role of the altitude level on cerebral autoregulation in residents at high altitude
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DOI：
10.1152/japplphysiol.01429.2006
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发表时间：
2007-08-01
影响因子：
3.3
通讯作者：
Ince, Can
中科院分区：
文献类型：
--
作者：
Jansen, Gerard F. A.;Krins, Anne;Ince, Can
居住在海拔4200米以上的喜马拉雅高原居民的大脑自动调节功能受损。这项研究是为了确定这种自我调节功能受损发生的高度。这项研究的第二个目的是验证一个假设，即在高海拔地区，给氧可以逆转这种自我调节的损害。对居住在海拔1330、2650、3440和4243米的四组10名喜马拉雅高原居民，在输注苯肾上腺素期间监测动脉氧饱和度（Sa(O2)）、血压和大脑中动脉血流速度，以确定大脑的静态自动调节。在此基础上计算脑自动调节指数（AI）。通常情况下，AI介于0到1之间。AI为0表示无自调节，AI为1表示完整的自调节。在1330 m （Sa(O2) = 97%）、2650 m （Sa(O2) = 96%）和3440 m （Sa(O2) = 93%）处，AI值（平均+/- SD）分别为0.63 +/- 0.27、0.57 +/- 0.22和0.57 +/- 0.15。在海拔4243 m处（Sa(O2) +/- 88%），人工智能为0.22 +/- 0.18 （P < 0.0005，与低海拔地区相比），在给氧（Sa(O2) = 98%）时，人工智能增加到0.49 +/- 0.23 （P = 0.008，配对t检验）。综上所述，居住在4243 m的高海拔地区的居民大脑自动调节功能几乎完全丧失，在给氧过程中有所改善。那些生活在海拔3440米及以下的人仍然有大脑自动调节功能。本研究表明，海拔3440 ~ 4243 m是一个过渡区，海拔较高的居民的SaO2含量为93% ~ 88%，在此区域以上，大脑自动调节功能严重受损。
Cerebral autoregulation is impaired in Himalayan high-altitude residents who live above 4,200 m. This study was undertaken to determine the altitude at which this impairment of autoregulation occurs. A second aim of the study was to test the hypothesis that administration of oxygen can reverse this impairment in autoregulation at high altitudes. In four groups of 10 Himalayan high-altitude dwellers residing at 1,330, 2,650, 3,440, and 4,243 m, arterial oxygen saturation ( Sa(O2)), blood pressure, and middle cerebral artery blood velocity were monitored during infusion of phenylephrine to determine static cerebral autoregulation. On the basis of these measurements, the cerebral autoregulation index ( AI) was calculated. Normally, AI is between zero and 1. AI of 0 implies absent autoregulation, and AI of 1 implies intact autoregulation. At 1,330 m ( Sa(O2) = 97%), 2,650 m ( Sa(O2) = 96%), and 3,440 m ( Sa(O2) = 93%), AI values ( mean +/- SD) were, respectively, 0.63 +/- 0.27, 0.57 +/- 0.22, and 0.57 +/- 0.15. At 4,243 m ( Sa(O2) +/- 88%), AI was 0.22 +/- 0.18 ( P < 0.0005, compared with AI at the lower altitudes) and increased to 0.49 +/- 0.23 ( P = 0.008, paired t-test) when oxygen was administered ( Sa(O2) = 98%). In conclusion, high-altitude residents living at 4,243 m have almost total loss of cerebral autoregulation, which improved during oxygen administration. Those people living at 3,440 m and lower have still functioning cerebral autoregulation. This study showed that the altitude region between 3,440 and 4,243 m, marked by SaO2 in the high-altitude dwellers of 93% and 88%, is a transitional zone, above which cerebral autoregulation becomes critically impaired.