[Ventilatory changes during laparoscopic cholecystectomy]

During the past 2 years in Europe and the USA laparoscopic cholecystectomy (LC) has become a widely practiced procedure. Nevertheless, the effects of long-lasting laparoscopic procedures on carbon dioxide elimination have not yet been systematically investigated. METHODS. Approval from the institutional research review board was obtained, as was written informed consent from the patients. Eleven patients undergoing LC were studied. Patient age ranged from 31 to 67 years. All patients received total intravenous anaesthesia (fentanyl, propofol, vecuronium, DHB). Controlled ventilation with a tidal volume of 12-14 ml/kg was administered. Before introduction of anaesthesia a cannula was inserted into the left radial artery. Blood gas analysis was undertaken just before introduction, just before insufflation of carbon dioxide, and thereafter at two intervals, after reaching an intra-abdominal pressure of 12 mm Hg, 15 min apart. Oxygen consumption and carbon dioxide output were measured using a calorimeter (Deltatrac TM, Datex). Intra-abdominal pressure was maintained at 12 mm Hg during the operation. RESULTS. After onset of the pneumoperitoneum inspiratory peak and plateau pressure showed an increase by more than 40%. During the operation respiratory minute volume had to be increased by about 30-40% to maintain normocapnia. Oxygen consumption remained nearly unchanged during the procedure while carbon dioxide output increased up to 38% 60 min after onset of the pneumoperitoneum. D(a-A) CO2 showed no significant change, indicating no increase in dead space. Beginning with the insufflation there was a significant increase in mean arterial pressure that lasted until the end of the procedure. CONCLUSION. The described effects of carbon dioxide insufflation, especially the extent of carbon dioxide resorption, define the need for careful monitoring of respiratory function during LC, especially in patients with preexisting cardiopulmonary disease.