抽象
隔膜强度可以通过膈压力(PDI)的测量响应于膈神经刺激进行评估。膜片的长度张力关系可以通过在肺容积的范围测量抽搐膈进行研究。肺容积和隔膜强度之间的关系的以前的研究已经使用的膈神经的电刺激的方法。在这些研究中,抽搐增强的现象并没有被考虑进去。先前已经表明,隔膜的现有收缩可以大大提高抽搐反应,从而影响测量值。本研究的目的是调查对于体积从残留体积(RV)在正常受试者肺总量(TLC)unpotentiated抽搐PDI和肺容积之间的关系。十分注意,以避免肌肉增强。为此,我们在刺激膈神经与磁刺激。此外,我们使用正压膨胀肺部高肺容量。上的长度张力关系抽搐增强作用的影响,通过使受试者之前膈神经刺激最大吸气努力研究。 The unpotentiated twitch Pdi decreased in a linear fashion with increasing lung volume over the full range of vital capacity by 0.54 kPa.L-1. Potentiation increased twitch Pdi by 40% at FRC and the effect was similar, in absolute terms, at all lung volumes. In relative terms, the effect of potentiation became greater as lung volume increased, and more than doubled twitch Pdi at TLC. With increasing lung volume, there is a linear fall in unpotentiated twitch Pdi with a slope that is less steep, over the same range of absolute lung volume, than previously reported. When assessing diaphragm strength by the twitch technique, it is essential to control for lung volume and equally important to control for twitch potentiation.