慢性阻塞性肺疾病中容积二氧化碳图死腔参数的变化及其临床价值

Changes and clinical value of dead space parameters in volumetric capnography of chronic obstructive pulmonary disease

目的探讨容积二氧化碳图(VCap)死腔参数在慢性阻塞性肺疾病(COPD)诊断中的应用价值。方法选取2013-2014年在我院门诊和住院治疗的74例COPD患者(COPD组)和38例健康志愿者(健康组)作为研究对象。测定受试者的肺通气、容量、弥散指标及Threshhold死腔(VDT)、Langley死腔(VDL)、Fowler死腔(VDF)、Wolff死腔(VDW)、Bohr死腔(VDB)参数。首先,在健康组中建立以死腔为应变量,性别、年龄、身高、体重、潮气量及呼吸频率为自变量的预计值计算公式,并运用公式计算各受试者的正常死腔预计值。采用配对t检验比较COPD组死腔预计值与实测值的差异。运用判别分析统计死腔对COPD患者和健康人的判别效率。采用偏相关分析统计死腔参数与常规肺功能参数的相关性。结果在COPD组中,VDT实测值[(79.51±39.29)m L]较预计值[(97.42±30.53)m L]减小(P<0.01),而VDF[(190.20±57.41)m L]、VDW[(214.04±73.35)m L]及VDB[(294.89±93.12)m L]实测值较预计值[(177.18±38.99)m L、183.86±46.63)m L、(237.44±62.27)m L]增大(P<0.05)。在运用死腔参数对COPD组和健康组的判别分析中只有VDT和VDB占预计值%进入判别函数,总归类正确率为87.9%(116/132)。在COPD组中,VDT及VDF与FEV1、FEV1/FVC、DLCO均呈负相关(P<0.05),VDW与FEV1、FEV1/FVC、DLCO均呈负相关(P<0.05),与RV、TLC呈正相关(P<0.05),VDB与FEV1、FEV1/FVC、DLCO均呈负相关(P<0.05),与RV、TLC、RV/TLC均呈正相关(P<0.05)。结论 VCap死腔对COPD的诊断及严重程度评估具有一定的临床参考价值。

Objective To investigate the application value of volumetric capnography(VCap) dead space parameters in diagnosis of chronic obstructive pulmonary disease(COPD). Methods Seventy-four patients with COPD(COPD group) and 38 healthy volunteers(healthy group) in our hospital for outpatient and inpatient treatment from 2013 to 2014 were selected as the research subjects. The pulmonary ventilation, volume and dispersion index, Threshold dead space(VDT), Langley dead space(VDL), Fowler dead space(VDF), Wolff dead space(VDW) and Bohr dead spaces(VDB) were measured in all the subjects. First, the formula for predicted value was obtained through multiple regression analysis with dead space as the dependent variable, and gender, age, height, weight, tidal volume, respiratory frequency as the independent variables. The predicted values of all subjects were computed by the formula. The difference between the predicted value and the measured value of dead space in COPD group was compared by paired t test. The discriminant efficiency of dead space on COPD patients and healthy people was analyzed by discriminant analysis. Correlations between dead space parameters and routine pulmonary function parameters were analyzed by partial correlation analysis. Results In the COPD group, the measured value of VDT was lower than the predicted value [(79.51±39.29) m L vs(97.42±30.53) m L, P<0.01], while the measured values of VDF, VDW, and VDB were significantly increased than the predicted values [(190.20±57.41) m L vs 177.18±38.99) m L,(214.04±73.35) m L vs(183.86±46.63) m L,(294.89±93.12) m L vs(237.44±62.27) m L, P<0.05]. In the discriminant analysis of dead space on COPD patients and healthy people, only VDT and VDB entered the equation, with the total classification accuracy of 87.9%(116/132). In COPD group, VDT and VDF were negatively correlated with FEV1, FEV1/FVC and DLCO(P<0.05). VDW was negatively correlated with FEV1, FEV1/FVC and DLCO(P<0.05), which was positively correlated with RV and TLC(P<0.05). VDB was negatively correlated with FEV1, FEV1/FVC and DLCO(P<0.05), but it was positively correlated with RV, TLC and RV/TLC(P<0.05). Conclusion VCap dead space has a certain clinical reference value for the diagnosis and severity evaluation of COPD.