呼出气CO_2容积曲线诊断COPD换气功能障碍的评价

Evaluation on CO_2 Volume Curve of Expiratory Air Diagnosing Dysfunction of Ventilation in Patients with COPD

目的评价无创肺换气肺功能诊断技术即呼出气CO2容积曲线诊断慢性阻塞性肺病(COPD)换气功能障碍的准确度及影响因素。方法采用病例对照研究。对照组94人,COPD组201例,主要分析参数:CO2max%、dC/dV3(%)、Vm25-50/VT、Vm50-75/VT。与常规肺功能各参数进行相关分析,比较四项主要诊断指标敏感度、特异度。结果VD-B(ml)、VD-B/VT、Vm25-50/VT、Vm50-75/VT、CO2max(%)、dC/dV2(%)、dC/dV3(%),两组比较差异有显著性意义(P<0.01);Vm25-50/VT、Vm50-75/VT、CO2max、dC/dV3与FVC、FEV1、DLCO、RV/TLC等常规肺功能指标中度相关(r=-0.4￣-0.6,P<0.01);Vm50-75/VT敏感度和特异度高于其它指标。结论(1)COPD患者VCap曲线形态异常,Ⅲ相斜率[dC/dV3(%)]明显增高且与阻塞严重程度相关。(2)变量Vm50-75/VT、Vm25-50/VT受生理因素及通气量的影响少,与常规肺功能指标显著相关,特别是DLCO功能(r=-0.566,-0.511,P<0.01)作为评价中、重度COPD换气功能障碍、通气/血流灌注失调指标,敏感度86%、特异度91%、准确度90%,能很好地区别正常对照组和COPD阻塞严重程度。(3)VCap方法简便快速、安全无创、患者依从性高、重复性好。(4)频数分布曲线与对照组有重叠,建议取最佳临界点为正常参考值。

Objective To evaluate the accuracy and influence factors of noninvasive diagnostic technique of pulmonary function（CO2 volume curve of expiratory air） for pulmonary gas exchange function in patients with chronic obstructive pulmonary diseases（COPD）.Method Contrast study was carried out.Tbere were 94 healthly people in control group and 201 patients in COPD group.The main variables included maximum CO2 concentration（CO2 max%）,the slope of phase 3（dC/dV3%/L）,volume between 25% and 50% of CO2max（Vm25-50）, volume between 50% and 75% of CO2max（Vm50-75）,tidal volume（VT）,Vm25-50/VT as well as Vm50-75/VT.Their correlation with various variables of routine pulmonary function was analyzed.Their sensitivity and specificity was compared.Results VD-B（ml）,VD-B/VT,Vm25-50/VT as well as Vm50-75/VT,CO2max（%）,dC/dV2（%） and dC/ dV3（%） were compared between two groups and there were significant differences（P〈0.01）.Vm25-50/VT,Vm50-75/VT,CO2max,dC/dV3 and FVC ,FEVI, DLCO, RV/TLC were moderately related （r=-0.4～-0.6,P〈0.01）,especially Vm50-75/VT had a higher sensitivity and specificity than any other parameters.Conclusions （1）The shape of VCap curve in patients with COPD is obviously exceptional.The slope of phase 3（dC/dV3%） rises prominently,and is correlated with the disease severity.（2）Vm50-75/VT and Vm25-50VT are hardly influenced by physiological factors and expired volume（VE）.They are prominently correlated with DLCO,RV/TLC and FEV1. In severe patients with COPD,the sensitivity,specificity and accuracy of Vms0_75/VT are 86%,91% and 90%, which can distinguish the control group and the severity of COPD. （3）VCap is a simple,non-invasive,secure and rapid bedside method in the diagnosis of patients with pulmonary gas exchange dysfunction. （4 ）The curves of control group and patients with COPD are partially overlapped.The optimal cut-off points are suggested to be used as normal reference values.