Vogelaere P, Deklunder G, Lecroart J
Hoger Instituut V. Lichamelijke Opvoeding, Vrije Universiteit Brussel, Belgium.
Int J Biometeorol. 1995 Aug;39(1):40-5. doi: 10.1007/BF01320892.
Five men, aged 31.2 years (SD 2.3), under semi-nude conditions and resting in a dorsal reclining position, were exposed to thermoneutral air for 30 min, followed immediately by a cold water (15 degrees C) immersion for 60 min. Cardiac output was measured using a dual-beam Doppler flow meter. During immersion in cold water, cardiac frequency (fc) showed an initial bradycardia. The lowest values were reached at about 10 min after immersion, 58.3 (SD 2.5) to 48.3 (SD 7.8) beats min-1 (P < 0.05). By the 20th min of exposure, fc had gradually risen to 70.0 beats min-1 (SD 6.6, P < 0.05). This change could be due to the inhibition of the initial vagal reflex by increased catecholamine concentration. Stroke volume (Vs) was significantly increased (P < 0.05) during the whole cold immersion period. Cardiac output, increased from 3.57 (SD 0.50) to 6.26 (SD 1.33) l min-1 (P < 0.05) and its change with time was a function of both Vs and fc. On the other hand, systolic flow acceleration was unchanged during the period of immersion. The changes in the respiratory variables (ventilation, oxygen uptake, carbon dioxide output and respiratory exchange ratio) during immersion showed an initial hyperventilation followed, as immersion proceeded, by a slower metabolic increase due to shivering.
五名年龄为31.2岁（标准差2.3）的男性，在半裸状态下以背卧位休息，先在热中性空气中暴露30分钟，随后立即浸入15摄氏度的冷水中60分钟。使用双束多普勒流量计测量心输出量。在浸入冷水中期间，心率（fc）显示出最初的心动过缓。在浸入后约10分钟时达到最低值，为58.3（标准差2.5）至48.3（标准差7.8）次/分钟（P<0.05）。到暴露20分钟时，fc已逐渐升至70.0次/分钟（标准差6.6，P<0.05）。这种变化可能是由于儿茶酚胺浓度增加抑制了最初的迷走反射。在整个冷水浸泡期间，每搏输出量（Vs）显著增加（P<0.05）。心输出量从3.57（标准差0.50）升至6.26（标准差1.33）升/分钟（P<0.05），其随时间的变化是Vs和fc两者的函数。另一方面，在浸泡期间收缩期血流加速度没有变化。浸泡期间呼吸变量（通气、摄氧量、二氧化碳排出量和呼吸交换率）的变化显示出最初的过度通气，随着浸泡的进行，由于颤抖导致代谢增加变慢。
