Jiang Z L, He J, Yamaguchi H, Tanaka H, Miyamoto H
Department of Physiology, School of Medicine, University of Tokushima, Japan.
Aviat Space Environ Med. 1994 Oct;65(10 Pt 1):936-43.
Blood flow velocity was measured in the common carotid artery of humans during breath-holding (BH) in the supine and upright positions, and during breath-hold face immersion (FIBH) in cold (20 degrees C) and warm (35 degrees C) water in the upright position with 90 degrees flexion of the upper body, to test the influences of the body position, facial immersion and temperature on changes in cerebral blood flow. Simultaneously, the heart rate (HR) and blood pressure (BP) under the same conditions, and the end-tidal PO2 and PCO2 (PETO2 and PETCO2) during supine BH, were also measured. Results showed that posture had no significant effect on the apneic HR. Bradycardia developed during cold FIBH, but not warm FIBH. The BP increased during BH in both positions, and during both cold and warm FIBH. The PETO2 decreased and the PETCO2 increased significantly at the end of BH. The blood velocity decreased transiently at the beginning of upright BH, but increased time-dependently during both supine and upright BH. Moreover, the velocity increased more during warm FIBH than during BH's, and even more during cold than warm FIBH. When bradycardia occurred during cold FIBH, the velocity integral per minute tended to decrease. These results suggest that the cerebral blood flow increases in these conditions of BH. This increase can be explained by the increase in PETCO2 and decrease in PETO2, possibly with a slight contribution from the increase in the BP.(ABSTRACT TRUNCATED AT 250 WORDS)
在仰卧位和直立位屏气（BH）期间，以及在上身90度屈曲的直立位、冷水（20摄氏度）和温水（35摄氏度）中进行屏气面部浸入（FIBH）时，测量人体颈总动脉的血流速度，以测试体位、面部浸入和温度对脑血流变化的影响。同时，还测量了相同条件下的心率（HR）和血压（BP），以及仰卧位屏气期间的呼气末PO2和PCO2（PETO2和PETCO2）。结果表明，体位对屏气时的心率无显著影响。在冷FIBH期间出现心动过缓，但在温FIBH期间未出现。在仰卧位和直立位屏气期间，以及在冷、温FIBH期间，血压均升高。屏气结束时，PETO2显著降低，PETCO2显著升高。直立位屏气开始时血流速度短暂下降，但在仰卧位和直立位屏气期间均随时间增加。此外，温FIBH期间的血流速度增加幅度大于屏气期间，冷FIBH期间的血流速度增加幅度甚至大于温FIBH期间。当冷FIBH期间出现心动过缓时，每分钟的速度积分趋于下降。这些结果表明，在这些屏气条件下脑血流增加。这种增加可以用PETCO2的增加和PETO2的降低来解释，可能血压的升高也有轻微贡献。（摘要截断于250字）
