Georgopoulos D, Mitrouska I, Bshouty Z, Anthonisen N R, Younes M
Section of Respiratory Diseases, University of Manitoba, Winnipeg, Canada.
Am J Respir Crit Care Med. 1996 May;153(5):1624-30. doi: 10.1164/ajrccm.153.5.8630612.
It has been shown in mechanically ventilated awake normal humans that increasing inspiratory flow rate (VI) exerts an excitatory effect on respiratory output. It is not known if this effect persists during sleep. To test this, seven normal adults were studied during wakefulness and non-rapid eye movement (non-REM) sleep. Subjects were connected through a nose mask to a volume-cycled ventilator in the assist/control mode, and VI was increased in steps (3 to 4 breaths each) from 30 to 70 L/min and then back to 30 L/min. VI pattern was square, and all breaths were subject-triggered. Forty-one trials during non-REM sleep and 10 during wakefulness were analyzed. Both during sleep and wakefulness minute ventilation increased and total breath duration (Ttot) decreased significantly in a graded and reversible manner as VI increased. These changes were complete in the first breath after VI transition. The response was significantly less during sleep than during wakefulness (p < 0.050; at 30 L/min Ttot, expressed as percent of that at 70 L/min, was 110.2 +/- 1.3% during sleep and 127.8 +/- 3.9% during wakefulness. During wakefulness, the rate of change in airway pressure before triggering the ventilator (dp/dt), an index of respiratory drive, increased significantly (p < 0.05) with increasing VI. During sleep dp/dt was not affected by VI changes. In four sleeping subjects the increase in VI was sustained for 1.5 to 2 min. There was no evidence for adaptation of the response; Ttot, averaged over the last three breaths, did not differ from that obtained with VI was sustained for only 3 to 4 breaths. We concluded that VI exerts an excitatory effect on respiratory output, mediated by a reflex neural mechanism, and the gain of this reflex is attenuated by sleep.
在机械通气的清醒正常人体中已表明，增加吸气流量（VI）对呼吸输出有兴奋作用。尚不清楚这种作用在睡眠期间是否持续。为了对此进行测试，对7名正常成年人在清醒和非快速眼动（非REM）睡眠期间进行了研究。受试者通过鼻罩连接到辅助/控制模式的容量控制通气机，VI以步长（每次3至4次呼吸）从30升/分钟增加到70升/分钟，然后再回到30升/分钟。VI模式为方形，所有呼吸均由受试者触发。分析了非REM睡眠期间的41次试验和清醒期间的10次试验。在睡眠和清醒期间，随着VI增加，分钟通气量均增加，总呼吸持续时间（Ttot）以分级和可逆的方式显著减少。这些变化在VI转变后的第一次呼吸中就已完成。睡眠期间的反应明显小于清醒期间（p <0.050；在30升/分钟时，Ttot以70升/分钟时的百分比表示，睡眠期间为110.2 +/- 1.3％，清醒期间为127.8 +/- 3.9％。在清醒期间，触发通气机之前气道压力的变化率（dp/dt），即呼吸驱动力指标，随着VI增加而显著增加（p <0.05）。在睡眠期间，dp/dt不受VI变化的影响。在4名睡眠受试者中，VI的增加持续了1.5至2分钟。没有证据表明反应会适应；最后三次呼吸的平均Ttot与VI仅持续3至4次呼吸时获得的Ttot没有差异。我们得出结论，VI通过反射神经机制对呼吸输出产生兴奋作用，并且这种反射的增益因睡眠而减弱。
