Department of Anaesthesia, University of Glasgow, Glasgow, UK.
Anaesthesia. 2010 Feb;65(2):167-71. doi: 10.1111/j.1365-2044.2009.06195.x. Epub 2009 Dec 1.
To investigate whether the established reductions in heart rate and cardiac output with hyperoxia in humans are primary effects or secondary to increases in systemic vascular resistance, we paced the hearts of nine patients with permanent pacemakers at a fixed rate when breathing either medical air (inspired O(2) fraction 0.21) or oxygen (inspired O(2) fraction 0.80) in a randomised, double-blind fashion. A thoracic bio-impedance machine was used to measure heart rate, stroke volume and blood pressure and calculate cardiac index and systemic vascular resistance index. Oxygen caused no change in cardiac index (p = 0.18), stroke index (p = 0.44) or blood pressure (p = 0.52) but caused a small (5.5%) increase in systemic vascular resistance index (p = 0.03). This suggests that hyperoxia has no direct myocardial depressant effects, but that the changes in cardiac output reported in previous studies are secondary to changes in systemic vascular resistance.
为了探究在人体中，高氧导致的心率和心输出量降低是原发性效应还是继发于全身血管阻力的增加，我们以随机、双盲的方式让九位装有永久性起搏器的患者在固定心率下呼吸医用空气（吸入氧分数 0.21）或氧气（吸入氧分数 0.80）。胸部生物阻抗仪用于测量心率、每搏输出量和血压，并计算心指数和全身血管阻力指数。氧气对心指数（p = 0.18）、每搏输出量（p = 0.44）或血压（p = 0.52）没有影响，但会使全身血管阻力指数小幅度增加（5.5%，p = 0.03）。这表明高氧没有直接的心肌抑制作用，但以前研究中报道的心输出量变化是继发于全身血管阻力的变化。
