Fukushima M, King L S, Kang K H, Banerjee M, Newman J H
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee.
J Appl Physiol (1985). 1990 Nov;69(5):1779-85. doi: 10.1152/jappl.1990.69.5.1779.
The causes of respiratory distress in O2 toxicity are not well understood. The purpose of this study was to better define the airway abnormalities caused by breathing 100% O2. Sheep were instrumented for measurements of dynamic compliance (Cdyn), functional residual capacity by body plethysmography (FRC), hemodynamics, and lung lymph flow. Each day Cdyn and FRC were measured before, during, and after the application of 45 min continuous positive airway pressure (CPAP) at 15 cmH2O. The amount of aerosol histamine necessary to reduce Cdyn 35% from baseline (ED35) was measured each day as was the response to aerosol metaproterenol. Cdyn decreased progressively from 0.083 +/- 0.005 (SE) 1/cmH2O at baseline to 0.032 +/- 0.004 l/cm H2O at 96 h of O2. Surprisingly, FRC did not decrease (1,397 +/- 153 ml at baseline vs. 1,523 +/- 139 ml at 96 h). The ED35 to histamine did not vary among days or from air controls. Metaproterenol produced a variable inconsistent increase in Cdyn. We also measured changes in Cdyn during changes in respiratory rate and static pressure-volume relationships in five other sheep. We found a small but significant frequency dependence of compliance and an increase in lung stiffness with O2 toxicity. We conclude that in adult sheep O2 toxicity reduces Cdyn but does not increase airway reactivity. The large reduction in Cdyn in O2 toxicity results from processes other than increased airway reactivity or reduced lung volume, and Cdyn decreases before the development of lung edema.
氧中毒时呼吸窘迫的原因尚未完全明确。本研究的目的是更好地界定吸入100%氧气所导致的气道异常情况。对绵羊进行仪器安装，以测量动态顺应性（Cdyn）、通过体容积描记法测量的功能残气量（FRC）、血流动力学以及肺淋巴流量。每天在施加15 cmH₂O的持续气道正压通气（CPAP）45分钟之前、期间和之后测量Cdyn和FRC。每天测量使Cdyn从基线降低35%所需的组胺气雾剂量（ED35），以及对沙丁胺醇气雾剂的反应。Cdyn从基线时的0.083±0.005（标准误）l/cmH₂O逐渐降低至吸氧96小时时的0.032±0.004 l/cmH₂O。令人惊讶的是，FRC并未降低（基线时为1397±153 ml，96小时时为1523±139 ml）。ED35对组胺的反应在各天之间或与空气对照组相比并无差异。沙丁胺醇使Cdyn产生了变化不定且不一致的增加。我们还在另外五只绵羊中测量了呼吸频率变化和静态压力-容积关系期间Cdyn的变化。我们发现顺应性存在微小但显著的频率依赖性，且氧中毒时肺硬度增加。我们得出结论，在成年绵羊中，氧中毒会降低Cdyn，但不会增加气道反应性。氧中毒时Cdyn的大幅降低是由气道反应性增加或肺容积减少以外的其他过程导致的，并且在肺水肿发生之前Cdyn就已降低。
