BACKGROUND: The deleterious cardiopulmonary side effects immediately after positioning in reverse Trendelenburg and CO2 intra-abdominal insufflation during a laparoscopic cholecystectomy are well tolerated in healthy patients but can lead to serious morbidity and mortality in patients with a limited cardiopulmonary reserve. Using a continuous and non-invasive cardiac output monitor based on partial CO2 rebreathing method, we investigated the immediate cardiopulmonary changes caused by positioning in reverse Trendelenburg and CO2 intra-abdominal insufflation during a laparoscopic cholecystectomy, and assessed the applicability of the partial CO2 rebreathing method for the measurement of cardiac output in a laparoscopic cholecystectomy. METHODS: The investigation was carried out on 11 patients undergoing a laparoscopic cholesystectomy. The control values of cardiac index (CI), cardiac output (CO), mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), systemic vascular resistance (SVR), dynamic compliance (Cdyn), airway resistance (Raw), peak inspiratory pressure (PIP) and end tidal CO2 partial pressure (PETCO2) were measured in the supine position after induction with target-controlled infusion of propofol (5 microgram/ ml). Five minutes after positioning in reverse Trendelenburg and CO2 insufflation, the same cardiopulmonay variables were measured and compared with the control values. RESULTS: CI, CO and CVP were reduced 33.3%, 31.9% and 29.0%, respectively (P < 0.05). MAP and SVR were increased 39.8% and 154.1%, respectively (P < 0.05). Cdyn was reduced 38.0% (P < 0.05). Raw and PIP were increased 22.8%, and 34.8%, respectively (P < 0.05), whereas HR and PETCO2 remained unchanged. CONCLUSIONS: The non-invasive cardiopulmonary monitor using partial CO2 rebreathing method, could be used with ease and safety in a laparoscopic cholecystectomy.