RETROPERITONEAL AND INTRAPERITONEAL CO2 INSUFFLATION HAVE MARKEDLY DIFFERENT CARDIOVASCULAR EFFECTS

Both retroperitoneoscopic and laparoscopic surgical approaches to kidn ey and adrenal gland have been reported but their cardiopulmonary path ophysiology has been incompletely characterized. To test the hypothesi s that these approaches have markedly different impact on the circulat ory and respiratory systems, we assessed at similar insufflation press ures alterations in cardiovascular and respiratory variables during re troperitoneal and intraperitoneal CO2 insufflation. Eighteen healthy, anesthetized (propofol, alfentanil, vecuronium), mechanically ventilat ed pigs were randomly instrumented for either retroperitoneoscopic (n = 9) or laparoscopic (n = 9) surgery. After CO2 insufflation cardiovas cular and respiratory variables were measured at four cavity pressures (baseline, 10, 15, and 20 mmHg), while end-expiratory CO2 tension was maintained by adjusting tidal volume. Data were analyzed for both ins ufflation-pressure-dependent and group effects by one-way and two-way ANOVA for repeated measurements, respectively, followed by Newman-Keul s post hoc test (P < 0.05). Cardiac output, mean arterial, pulmonary a rtery, central venous, and femoral venous pressures increased signific antly in both groups in an insufflation-pressure-dependent fashion. Ho wever, changes in cardiac output (P < 0.001), pulmonary artery (P < 0. 007), central venous (P < 0.001), and iliac venous pressures (P < 0.00 1) for the same insufflation pressure were markedly and significantly greater with intraperitoneal than retroperitoneal CO2 insufflation. Mo st important, intraperitoneal unlike retroperitoneal insufflation indu ced a marked inferior vena caval pressure gradient (8.9 +/- 1.1 mmHg v s 1.0 +/- 0.5 mmHg, P < 0.00001). While both retroperitoneal and intra peritoneal CO2 insufflation required increased tidal volumes to adjust end-tidal CO2 tension to baseline, intraperitoneal CO2 insufflation r esulted in a significantly greater increase of mixed venous and arteri al carbon dioxide tensions (P < 0.007) even at similar insufflation pr essures. Furthermore, significantly greater peak airway pressures (P = 0.018) were required with intraperitoneal than with retroperitoneal i nsufflation to administer the same tidal volume, indicating a greater decrease in quasi-static compliance with intraperitoneal insufflation (P = 0.0436). Thus, (i) cardiovascular and respiratory changes are muc h less during retroperitoneal than intraperitoneal CO2 insufflation, e ven at the same insufflation pressures, and (ii) retroperitoneal CO2 i nsufflation unlike intraabdominal CO2 insufflation does not induce an inferior vena caval pressure gradient and hence does not appear to imp air systemic lower body venous return up to insufflation pressures of 20 mmHg. (C) 1997 Academic Press.