Assessment Of The Severity On Chronic Obstructive Pulmonary Disease By Volumetric Capnography

ObjectiveTo explore the correlation between volumetric capnography (VCap) and traditional pulmonary function on chronic obstructive pulmonary disease (COPD), try to get the indexes of VCap which were related to the severity on COPD, which could replace the indexes of traditional pulmonary function when some older patients with COPD could not accept traditional pulmonary function testing.Methods390 patients admitted to Fujian Geriatric Hospital from June in 2008 to June in 2010 for testing pulmonary function were included in the study. They were divided into 2 groups: (1)the COPD group:260 cases(average age 76.57±6.38);(2)the control group:130 cases(average age 76.00±7.74).The COPD group was divided into 4 subgroups(COPDⅠ～COPDⅣ).All persons were tested with traditional pulmonary function and VCap. Receiver operating characteristic curve(ROC) was used for evaluating the diagnostic value of COPD by the indexes of VCap.Results1. C02max, VD-B/VT, VD-F/VT, Vm25-50/VT, Vm50-75/VT, dC/dV3, SR23 of VCap in the COPD group were higher than those in the control group, and dC/dV2 of VCap in the COPD group was lower than that in the control group. VD-B/VT, VD-F/VT, Vm25-50/VT, Vm50-75/VT, dC/dV3, SR23 of VCap were statistically significant(P<0.05), while C02max and dC/dV2 of VCap were not statistically significant(P>0.05).2. Vm25-50/VT, Vm50-75/VT, dC/dV3, SR23 of VCap in the 4 subgroups(COPDⅠ～ COPDⅣ) compared with the control group that the difference was statistically significant(P<0.05), while dC/dV2 of VCap was not statistically significant(P>0.05). C02max of VCap in the COPD(Ⅲ～Ⅳ) group (severe and very severe group) was statistically significant(P<0.05), while VD-B/VT, VD-F/VT of VCap in the COPD(Ⅱ～Ⅳ) group(from moderate to very severe group ) were statistically significant(P<0.05).3. C02max, VD-B/VT, VD-F/VT, Vm25-50/VT, Vm50-75/VT, dC/dV3, SR23 of VCap and VC% of predicted, FVC%pre, FEV1%pre, FEV1/FVC, Kco%pre, DLco%pre of traditional pulmonary function correlated negatively.4. In a number of indexes of Vcap, the specificity of Vm25-50/VT for the diagnosis of COPD was best (0.900), but its sensitivity was poor than other indexes. Which the Sensitivity and specificity were good was Vm50-75/VT and dC/dV3.Conclusions1. Vm25-50/VT, Vm50-75/VT, dC/dV3 and SR23 of VCap as the illness progress could be gradually increasing when the patients with COPD appeared in the mild airflow limited, and VCap was abnormal. Tip 4 afore-mentioned indexes were sensitive indexes, while dC/dV2 of VCap had no significance on the diagnosis of COPD and assessment of the severity. C02max of VCap might be one of the indexes to assess the severity of severe COPD or above. VD-B/VT and VD-F/VT of VCap might be one of the indexes for assessment of the severity of moderate COPD or above.2. dC/dV3 and FEV1%pre of VCap were highly correlated (r=-0.70991) on the diagnosis of COPD and assessment of the severity.3. The best critical value: VD-B/VT<37.215%, Vm25-50/VT<5.705%, Vm50-75/VT<11.120%, dC/dV3<1.0250%/L and SR23<6.5550%.