BACKGREOUND: The pneumonectomy may depress the right ventricular (RV) function transiently. The thermodilution ejection/volumetric catheter is known to be most useful method assessing the changes in RV performance during pulmonary resection. The purpose of this study was to examine the RV function during and immediately after pneumonectomy using thermodilution methods. METHODS: 16 patients undergoing pneumonectomy were studied. After induction of anesthesia, a multilumen thermodilution catheter mounted with a rapid response thermister was inserted. Using computer system, RV ejection fraction (RVEF), cardiac output, and RV end-diastolic volume (RVEDV) were measured when the patient was in lateral position (control), after one lung ventilation (OLV) and the main pulmonary artery ligated, and at the completion of resection. Arterial blood gases were analyzed and pulmonary vascular resistance (PVR) was calculated. RESULTS: Systolic pulmonary blood pressure (SPAP)(28.3 +/- 6.2 mmHg) increased compared to the control (24.6 +/- 5.9) without a significant change of PVR. No statistically significant difference was found in either RVEF or RVEDV at each times. CONCLUSIONS: Our study demonstrate the pneumonectomy do not depress the RV function immediately and RVEF do not show any correlation with PVR or RVEDV.