Pulmonary capacity in lung cancer patients prior to lung resection--comparison of the unilateral pulmonary artery occlusion test with expired gas analysis during exercise testing.

We attempted to determine if expired gas analysis during exercise testing has equal value to the unilateral pulmonary artery occlusion test (UPAO). Sixty-four lung cancer patients were evaluated. We performed UPAO and measured mean pulmonary artery pressure (PPA) and cardiac output (C.O.) 15 min later, and calculated total pulmonary vascular resistance (TPVR). Expired gas analysis during exercise testing was performed, and the maximum oxygen consumption per unit body surface area (VO2max/m2) and the anaerobic threshold (AT/m2) were calculated. The patients were divided into two groups according to the PPA as follows: Group PPA(L) and Group PPA(H), and the TPVR as follows: Group TPVR(L) and Group TPVR(H). Comparative studies of the mean values of VO2max/m2 and AT/m2 were performed between the two groups. VO2max/m2 was significantly higher in Group PPA(L) than in Group PPA(H). VO2max/m2 was significantly higher in Group TPVR(L) than in Group TPVR(H). TPVR and VO2max/m2 showed no significant correlation, but a weak negative quadratic correlation with the equation y = 2276-246.6 logx was found. This result led a minimal acceptable levels for lung resection of Vo2max/m2 of 650 ml/min/m2 corresponding to the TPVR levels of 700 dyne.sec.cm5/m2.