EFFECTOR OF HEMODYNAMICS DURING LAPAROSCOPY - CO2 ABSORPTION OR INTRAABDOMINAL PRESSURE

Controversy has been raised about the effects of systemic carbon dioxi de accumulation versus the intra-abdominal pressure on hemodynamics du ring laparoscopy. We compared the acid-base and hemodynamic changes du ring pneumoperitoneum in a randomized cross-over study between CO2 and nitrogen gases to test the hypothesis that the CO2 absorbed during la paroscopy, rather than the 15 mmHg intra-abdominal pressure created, a ccounted for these changes. Eight adult pigs were anesthetized and ven tilated with a fixed minute ventilation. Metabolic function was measur ed from analysis of expired flow by a metabolic measurement cart. Afte r baseline periods, animals were randomized into two groups, for 2 hr of either CO2 or nitrogen pneumoperitoneum at 15 mmHg intra-abdominal pressure, followed by 1 hr of recovery. After at least a 48-hr recover y period, the experiment was repeated with the other gas. Metabolic da ta revealed that there was a significant absorption of CO2 gas across the peritoneal epithelium during CO2 pneumoperitoneum. Animals insuffl ated with CO2 gas experienced a 75% increase in pulmonary CO2 excretio n, with significant acidemia and hypercapnia, whereas there were no ac id-base disturbances in those with nitrogen insufflation. Oxygen consu mption remained essentially unchanged in both groups, even during pneu moperitoneum. CO2 pneumoperitoneum was also associated with systemic a nd pulmonary arterial hypertension and a reduction in stroke volume of up to 15%. Pneumoperitoneum alone did not compromise hemodynamics. Pn eumoperitoneum using CO2 gas during laparoscopy resulted in systemic C O2 absorption across the peritoneum. This led to acidemia, hypercapnea , and depressed hemodynamics. The intra-abdominal pressure routinely u sed during laparoscopic surgery did not affect metabolic function, aci d-base balance, or hemodynamics in the experimental model. (C) 1995 Ac ademic Press, Inc.