Measurement of Pulmonary Diffusing Capacity for Carbon Monoxide(D_LCO)in Application to Chronic Obstructive Pulmonary Diseases

The pulmonary diffusing capacity for carbon monoxide(D_LCO)was measuredin 50 normal subjects,50 patients with emphysema and 31 with asthma.The results sh-owed that the D_LCO value of the asthma group was markedly higher than that of thehealthy group,while the D_LCO/pr% and KCO values of the asthma group were similarto those of the healthy group.The values of D_LCO,D_LCO/pr% and KCO in the emphy-sema group were very significantly lower than those in the asthma and healthy groups.Our study suggests that the measurement of D_LCO is onc of the useful pulmonary func-tion tests in differentiation of emphysema from asthma.The mechanism ofdiffcrcnt D_LCOvalues between emphysema and asthma is discussed.The D_LCO values in patients withmild to severe emphysema gradually decreased with the severity of emphysema.The KCOvalues between the mild emphysema and healthy groups were dramatically different.Thisis helpful in the early diagnosis of emphysma as combined with other clinical data.