BACKGROUNDTo explore the characteristics and clinical significance of diffusing capacity in the patients with lung cancer.

METHODSThe pulmonary diffusing capacity for carbon monoxide (DLCO) was measured with the rebreathing method in 138 patients with primary lung cancer, and 86 were performed pulmonary resection.

RESULTSThere was no significant difference in DLCOrb and DLCOrbc between the groups with different histological type and degree of ventilation impairment and general type (P > 0.05). DLCOrb/VA mildly decreased in the patients whose lung ventilation function was normal. DLCOc/VA decreased in the patients with restrictive ventilation dysfunction (P < 0.01), and DLCOrb/VA decreased in the patients with obstructive and mixed ventilation dysfuncion (P < 0.05). DLCOc/VA decreased in the patients with light and obvious lung dysfunction (P < 0.05). DLCOc/VA in the patients with central lung cancer was lower than that in the peripheral ones (P < 0.01). DLCOc/VA and D LCOrb in the group with postoperative respiratory failure were lower than that in the group without respiratory failure (P < 0.05). When DLCOc/VA of less than 80% and DLCOrb/VA of less than 70% were used to predict the postoperative respiratory failure, the correct ratios of dignosis and the diagnostic indexes were high.

CONCLUSIONSThe diffusing capacity decreases in the patients with lung cancer, and the main manifestation is the abnormal DLCOrb/VA and DLCOc/VA. The general type of lung cancer and the degree of pulmonary dysfunction may influence the diffusing function of the patients. DLCOc/VA of less than 80% and DLCOrb/VA of less than 70% should be selected for predicting postoperative respiratory failure.