Cortese D A, Rodarte J R, Rehder K, Hyatt R E
J Appl Physiol. 1976 Oct;41(4):474-9. doi: 10.1152/jappl.1976.41.4.474.
The effect of posture on phase III (alveolar nitrogen plateau) and phase IV (closing capacity) of the single-breath oxygen test was examined in 10 normal people. In part 1 of the study, subjects inspired and expired in the standing, supine, prone, and right lateral decubitus positions; there was no effect of posture on phase IV but slopes of phase III were higher when subjects were in the supine and lateral positions. In part 2, subjects inspired in the standing position and expired in one of the recumbent positions. Phase IV occurred infrequently except in the prone position (6 of 10 subj); slopes of phase III in part 2 were not consistently altered by changing posture. It is difficult to explain the failure of posture to alter phase IV solely on a model requiring a linear gradient of pleural pressure. The slope of phase III appears to depend more on the emptying patterns of small regions with widely varying volume-to-ventilation ratios than on gravity-dependent sequences of emptying. Finally, the data suggest a considerable similarity between the upright and prone positions in terms of lung filling and emptying.
在10名正常人中研究了姿势对单次呼吸氧试验的第三相（肺泡氮平台）和第四相（闭合容量）的影响。在研究的第一部分，受试者分别在站立、仰卧、俯卧和右侧卧位进行吸气和呼气；姿势对第四相没有影响，但当受试者处于仰卧位和侧卧位时，第三相的斜率更高。在第二部分中，受试者在站立位吸气，在其中一个卧位呼气。除俯卧位外（10名受试者中有6名），第四相很少出现；改变姿势并未使第二部分中第三相的斜率发生一致变化。仅基于需要胸膜压力线性梯度的模型，很难解释姿势未能改变第四相的原因。第三相的斜率似乎更多地取决于具有广泛不同容积与通气比的小区域的排空模式，而不是取决于重力依赖的排空顺序。最后，数据表明在肺的充盈和排空方面，直立位和俯卧位之间存在相当大的相似性。
