Derenne J P, Whitelaw W A, Couture J, Milic-Emili J
Respir Physiol. 1986 Sep;65(3):303-14. doi: 10.1016/0034-5687(86)90015-0.
To investigate the mechanisms by which human subjects prevent or compensate for the change in respiratory muscle length imposed by applying continuous positive pressure to the airways, six men were studied under general anesthesia with methoxyflurane at the end of a minor surgical procedure (rhinoplasty). Ventilatory and occlusion pressure response to carbon dioxide was measured by a rebreathing technique with no bias pressure, or with 16 cm H2O positive pressure produced by adding weights to a spirometer bell. Static pressure-volume curves of the respiratory system were obtained while the subjects were paralyzed with succinyl choline. In contrast to awake subjects described in other studies, the anesthetized patients did not activate expiratory muscles to combat the rise in end-expiratory level caused by pressure, and showed little evidence of enhanced activation of inspiratory muscles that in the conscious state compensates for the disadvantage of their shorter length. A change in the shape of the occlusion pressure wave, however, suggested that positive pressure had some effect on the neural discharge to inspiratory muscles. The mechanisms by which the respiratory system defends itself against a pressure load that tends to change end-expiratory level are sensitive to anesthesia and may require consciousness.
为了研究人类受试者预防或补偿因气道持续正压通气导致的呼吸肌长度变化的机制，在一台小型外科手术（隆鼻术）结束时，对6名男性在甲氧氟烷全身麻醉下进行了研究。通过无偏压的重复呼吸技术，或通过在肺活量计钟罩上加砝码产生16 cm H₂O正压的方式，测量对二氧化碳的通气和闭塞压力反应。在受试者被琥珀酰胆碱麻痹时，获取呼吸系统的静态压力-容积曲线。与其他研究中描述的清醒受试者不同，麻醉患者并未激活呼气肌来对抗由压力导致的呼气末水平升高，并且几乎没有证据表明吸气肌的激活增强，而在清醒状态下吸气肌激活增强可弥补其较短长度的劣势。然而，闭塞压力波形状的改变表明正压对吸气肌的神经放电有一定影响。呼吸系统抵御倾向于改变呼气末水平的压力负荷的机制对麻醉敏感，可能需要意识参与。
