HEMODYNAMIC EVENTS IN THE PERITONEAL ENVIRONMENT DURING PNEUMOPERITONEUM IN DOGS

The purpose of this experimental study was to determine the hemodynamic conditions of intraperitoneal viscera during pneumoperitoneum by using either CO2 gas or helium (He) for insufflation. In 16 mongrel dogs (divided into a CO2 group and an He group) subjected to 14 mmHg pneumoperitoneum for 60 min, the following parameters were assessed at times before and 1, 2, 5, 15, 30, 45, and 60 min thereafter: (1) intestinal mucosal blood flow, by means of a laser-Doppler probe inplanted into a jejunal loop; (2) portal pressure and portal blood pCO2, through a catheter inserted via a mesenteric jejunal vein; (3) intramural jejunal pH (pHi), by means of a Tonometer, which expresses the degree of tissue ischemia; (4) inferior vena cava pressure and blood pCO2, through a catheter inserted via a femoral vein; and (5) from the systemic circulation pulse rate, arterial blood pressure, CO, CVP, PVP, SaO2, pCO2, and p(a)O2 were measured through a catheter placed into a femoral artery and a Swan-Ganz thermodilution catheter inserted via the external jugular vein: CI and SVR were then calculated. Jejunal mucosal blood flow was found decreased (P < 0.0001) and pHi revealed gut mucosal ischemia. Portal and inferior vena cava pressures were found to be elevated (P < 0.0001), as was blood pCO2 of these vessels (P < 0.001), in only the CO2 group. From the systemic circulation, arterial blood pressure, CO, CI, SaO2, and p(a)O2 revealed a decrease (P < 0.001) while arterial pCO2 (only CO2 group), CVP, SVR, and PVP revealed an increase (P < 0.001). We conclude that severe hemodynamic alterations, not only to the systemic circulation but mainly to the viscera of the peritoneal cavity, are prominent after pneumoperitoneum for laparoscopic surgery. Elevation of portal and inferior vena cava pressures leads to splanchnic blood flow congestion and ischemia, while the use of CO2 seems to directly influence the pCO2.