慢性阻塞性肺疾病机械通气呼吸力学容积依赖性系数与内源性呼气末正压的相关性分析

Correlation between volume dependence of respiratory mechanics and intrinsic positive end-expiratory pressure in COPD patients mechanically ventilated

目的探讨慢性阻塞性肺疾病（COPD）患者机械通气时呼吸力学非线性分析时呼吸系统弹性和阻力的容积依赖性系数（Evd／Rvd）与内源性呼气末正压（PEEPi）的相关性。方法2004年1月-2005年1月本院英东重症监护医学中心收治的25例COPD机械通气患者，分别以呼吸力学的线性和非线性模型分析其压力（P）、流量（V’）和容量（V）数据，比较二者的拟合效率指标决定系数（R。）和根均方差（RMSD）；以呼气末阻断法测定PEEPi，分析弹性容积依赖性系数（Evd）、阻力容积依赖性系数（Rvd）以及Evd×Rvd与PEEPi的相关性。结果非线性分析所得的RMSD值（1．47±0．81）cmH2O小于线性分析所得（2．36±1．18）cmH2O；非线性分析所得的R。值（0．97±0．02）大于线性分析（0．89±0．08），差异均有统计学意义（P均〈0．05）；Evd、Rvd以及Evd×Rvd与PEEPi的相关系数分别为0．90、0．82和0．95（P均〈0．01）。结论呼吸力学的非线性模型比线性模型更加适合COPD患者机械通气时呼吸力学分析。Evd和Rvd，特别是Evd×Rvd与PEEPi之间具有良好的相关性，或可用于COPD患者机械通气时PEEPi的无创性持续监测。

Objective To investigate the correlation between intrinsic positive end-expiratory pressure （PEEPi） and volume dependence of elastance and resistance of respiratory system （Evd/Rvd） origined from non-linear analysis of respiratory mechanics in COPD patients mechanically ventilated. Methods Twenty-five COPD patients mechanically ventilatd were recruited in the study. The data of pressure （ P）, flow（ V＇ ） and volume （ V ） were analyzed by linear and non-linear mode of respiratory motion respectively. RMSD and R2 were compared between the two methods. PEEPi was determined by end-expiratory occlusion method. The correlation between PEEPi and Evd, Rvd as well as Evd x Red was examined. Results The mean values of RMSD of linear and non-linear analyses of respiratory mechanics were （2.36 ± 1.18 ） and （ 1.47 ±0.81 ） cm H2O respectively, whereas for R2 were （0.89 ±0.08 ） and （ 0.97 ±0.02 ） respectively （ P 〈 0. 05）. The correlation coefficients of PEEPi with Evd,Rvd as well as Evd x Rvd were 0.90,0.82 and 0.95 respectively（P 〈0.01 ）. Conclusions Non-linear mode of respiratory motion is better to analyse respiraoty mechanics of COPD patients mechanically ventilated. There are positive correlations of PEEPi with Evd, Rvd as well as Evd × Rvd, which may be good predictors of PEEPi in mechanically ventilated COPD patients.