颤搐性跨膈压与肺容量的关系的研究

The relationship between twitch transdiaphragmatic pressure and lung volume

目的探讨颈部膈神经磁波刺激时,肺容量位对颤搐性跨膈压(Twitch transdiaphragmatic pressure,Pdi(t))的影响,确定膈肌最适初长时的肺容量位,从而为临床上评估COPD膈肌功能及合理确定肺减容术减容范围提供参考依据。方法观察7名健康成人在颈椎磁刺激时,不同肺容量(RV、FRC-1/2ERV、FRC、FRC+1/5IC、FRC+2/5IC、FRC+3/5I、FRC+4/5IC、TLC)位所诱发的Pdi(t)的变化。结果 Pdi(t)在RV位时最大(34.18±8.8)cmH2O,随着肺容量的增加而呈线性下降,在TLC位达到最低值(5.83±5.64)cmH2O。两者的线性回归方程为:Y=31.17-0.26X[(Y为Pdi(t),单位cmH2O;X为肺容量,用%VC来标化;r=0.98,P<0.01)]。结论膈肌的最适初长位于RV,磁刺激膈神经所诱发的Pdi(t)最大,并随着肺容量位的增加而呈线性下降。

[ Objective ] To investigate the influence of lung volume on twitch transdiaphragmatic pressure Pdi（t） and determine the lung volume corresponding to optimal diaphragm muscle length, which provide objectivebasisfor evaluating diaphragmatic function and the reference range of volume reduced in lung volume reduction surgery （LVRS） in clinics. [ Methods ] In 7 normal subjects, changes in the twitch transdiaphragmatic pressure Pdi（t） elicited by cervical magnetic stimulation at various levels of lung volume（RV, FRC-1/2ERV, FRC, FRC＋I/5IC, FRC＋2/5IC, FRC＋3/5IC, RC＋4/5IC, TLC） were observed. The diaphragmatic force output was reflected by above parameters. [Results] At RV, Pdi（t） reached to peak[（34.18_＋8.8）cmH20）] and decreased linearly as the lung volume increased, with its minimum at TLC （5.83±5.64）cmHzO. The linear regression equation for Pdi （t）= 31.17-0.26X （r =0.98, P 〈 0.01）. [Conclusions] The optimal initial length of diaphragm muscle is RV, which is also below FRC in normal subjects. Above the lung volume corresponding to the opumal initial length, Pdi （t） is decreased linearly as the lung volume increases, with the slope of 0.26 cmH2O/%VC.