The adverse hemodynamic effects of anesthesia, head-up tilt, and carbon dioxide pneumoperitoneum during laparoscopic cholecystectomy

Background: The increased intra-abdominal pressure during pneumoperitoneum, together with the head-up tilt used in upper abdominal laparoscopies, woul d be expected to decrease venous return to the heart. The goal of our study was to determine whether laparoscopy impairs cardiac performance when prev entive measures to improve venous return are taken, and to analyze the effe cts of positioning, anesthesia, and increased intra-abdominal pressure. Methods: Using invasive monitoring, hemodynamic changes were investigated i n 15 ASA class I or II patients under isoflurane-fentanyl anesthesia during laparoscopic cholecystectomy. Before laparoscopy, the patients received an intravenous (IV) infusion of colloid solution if cardiac filling pressures were low, and their legs were wrapped from toes to groin with elastic band ages. Measurements were taken while the patients were awake in the supine ( baseline) and head-up tilt (15-20 degrees) positions, and after the inducti on of anesthesia in the same positions. Measurements were repeated at regul ar intervals during laparoscopy (intra-abdominal pressure at 13-16 mmHg), a fter deflation of the gas, and in the recovery room. Results: With the passive head-up tilt in awake and anesthetized patients, the cardiac index (CI), stroke index (SI), central venous pressure (CVP), a nd pulmonary capillary wedge pressure (PCWP) decreased, and systemic vascul ar resistance increased. With the patient under anesthesia, SI decreased, b ut CI did not change significantly as a result of the compensatory increase in heart rate. Carbon dioxide (CO2) insufflation at the start of laparosco py produced increases in CVP and PCWP as well as mean systemic and mean pul monary arterial pressures without changes in CI or SL Toward the end of the laparoscopy, CI decreased by 15%. The hemodynamic values returned to nearl y prelaparoscopic levels after deflation of the gas, and CI was elevated du ring the recovery period, whereas systemic vascular resistance was decrease d in comparison with the baseline. Conclusions By correcting relative dehydration and preventing the pooling o f blood, CI decreased less than 20% during pneumoperitoneum as compared wit h the baseline awake level. The head-up positioning accounts for many of th e adverse effects in hemodynamics during laparoscopic cholecystectomy.