Stark A R, Cohlan B A, Waggener T B, Frantz I D, Kosch P C
J Appl Physiol (1985). 1987 Mar;62(3):1117-23. doi: 10.1152/jappl.1987.62.3.1117.
To investigate the regulation of end-expiratory lung volume (EEV) in premature infants, we recorded airflow, tidal volume, diaphragm electromyogram (EMG), and chest wall displacement during sleep. In quiet sleep, EEV during breathing was 10.8 +/- 3.6 (SD) ml greater than the minimum volume reached during unobstructed apneas. In active sleep, no decrease in EEV was observed during 28 of 35 unobstructed apneas. Breaths during quiet sleep had a variable extent of expiratory airflow retardation (braking), and inspiratory interruption occurred at substantial expiratory flow rates. During active sleep, the expiratory flow-volume curve was nearly linear, proceeding nearly to the volume axis at zero flow, and diaphragm EMG activity terminated near the peak of mechanical inspiration. Expiratory duration (TE) and inspiratory duration (TI) were significantly shortened in quiet sleep vs. active sleep although tidal volume was not significantly different. In quiet sleep, diaphragmatic braking activity and shortened TE combined to maintain EEV during breathing substantially above relaxation volume. In active sleep, reduced expiratory braking and prolongation of TE resulted in an EEV that was close to relaxation volume. We conclude that breathing strategy to regulate EEV in premature infants appears to be strongly influenced by sleep state.
为了研究早产儿呼气末肺容积（EEV）的调节机制，我们记录了睡眠期间的气流、潮气量、膈肌肌电图（EMG）以及胸壁位移。在安静睡眠状态下，呼吸过程中的EEV比无梗阻性呼吸暂停期间达到的最小容积大10.8±3.6（标准差）ml。在活跃睡眠状态下，35次无梗阻性呼吸暂停中有28次未观察到EEV下降。安静睡眠期间的呼吸具有不同程度的呼气气流阻滞（制动），吸气中断发生在相当高的呼气流量时。在活跃睡眠期间，呼气流量-容积曲线几乎呈线性，在零流量时几乎延伸至容积轴，膈肌EMG活动在机械吸气峰值附近终止。与活跃睡眠相比，安静睡眠期间的呼气持续时间（TE）和吸气持续时间（TI）显著缩短，尽管潮气量无显著差异。在安静睡眠中，膈肌制动活动和TE缩短共同作用，使呼吸期间的EEV维持在明显高于松弛容积的水平。在活跃睡眠中，呼气制动减少和TE延长导致EEV接近松弛容积。我们得出结论，早产儿调节EEV的呼吸策略似乎受睡眠状态的强烈影响。
