Inquiry on Pulmonary Diffusion Function Indices of DLco and Kco as Applied in Diagnosing Pulmonary Diseases

A study was made on the effects of relevant factors on pulmonary diffusion function and applicability of diffusion measurements in space medicine. In this experiment, diffusion measurements were made using single breath method in 120 healthy subjects and 76 patients with lung diseases. A comparative analysis was also made. The results showed that DLco and Kco in healthy subjects decreased with age. While DLco was found to be higher in male than female, positively correlated with body height, and increased with increase of VC and TLC. Kco was not affected by body height, sex or lung volume, but increased with increased percentage of FEV1 and decreased with increased percentage of RV. Although the effects of pulmonary capacity and ventilation on DLco and Kco are different, their percentages in the predicted values are similar. It showed that their changes in healthy subjects are synchronous. Both of the two parameters decreased in various pulmonary diseases. However, Kco had a sensitive response in chronic obstructive pulmonary diseases, which may be used as an index for early diagnosis of pulmonary emphysema. DLco decreased remarkably in restructive pulmonary diseases. It indicates that the two indexes of diffusion capacity respond differently to different pulmonary diseases. It may be helpful when these two parameters of pulmonary diffusion are used in combination in determining impairment in diffusion capacity for early diagnosis of pulmonary diseases.