Bindslev L, Hedenstierna G, Santesson J, Norlander O, Gram I
Acta Anaesthesiol Scand. 1980 Jun;24(3):199-205. doi: 10.1111/j.1399-6576.1980.tb01534.x.
Airway closure, functional residual capacity (FRC) and the transpulmonary pressure volume relationship of each lung were studied in the anaesthetized subject in the supine and the left lateral positions. In the supine posture, FRC was of approximately the same size in each lung as was closing capacity (CC). CC exceeded FRC in either lung. In the left lateral position, FRC was increased by 0.91 in the non-dependent lung and was reduced by 0.21 in the dependent lung, while CC was unaltered in either lung. Consequently, FRC exceeded CC in the non-dependent lung and was further lowered beneath CC in the dependent lung. Airway closure did not occur in the non-dependent lung until an average of 0.51 of gas had been expelled after the dependent lung had ceased to empty. The addition of positive end-expiratory pressure (PEEP) in the range 0.5-2 kPa, increased FRC more in the non-dependent than the dependent lung. The findings suggest that airway closure is evenly distributed in the horizontal level, while it has a discontinuous distribution between the dependent and non-dependent lung. Moreover, the increase in lung volume caused by PEEP has a distribution that is by no means ideal for the purpose of countering airway closure.
在麻醉状态下的受试者处于仰卧位和左侧卧位时，研究了气道闭合、功能残气量（FRC）以及每侧肺的跨肺压力容积关系。在仰卧姿势下，每侧肺的FRC大小与闭合容量（CC）大致相同。任何一侧肺的CC均超过FRC。在左侧卧位时，非下垂肺的FRC增加了0.91，下垂肺的FRC减少了0.21，而任何一侧肺的CC均未改变。因此，非下垂肺的FRC超过了CC，而下垂肺的FRC则进一步降至CC以下。直到下垂肺停止排空后平均呼出0.51的气体，非下垂肺才会发生气道闭合。在0.5 - 2 kPa范围内添加呼气末正压（PEEP）时，非下垂肺的FRC增加幅度大于下垂肺。研究结果表明，气道闭合在水平层面上分布均匀，而在下垂肺和非下垂肺之间则呈间断分布。此外，PEEP引起的肺容积增加对于对抗气道闭合而言，其分布绝不是理想的。
