The adverse effects of intraabdominal pressure from capnoperitoneum on cardiovascular and pulmonary systems have been well documented, but the effects on portal pressures in dogs with various insufflation pressures is poorly defined. The aim of the present study was to measure the effect of insufflation pressures on portal pressures, using direct pressure measurements in patients undergoing laparoscopy. We hypothesized that portal pressure would increase in a direct linear relationship to insufflation pressure. Nine dogs undergoing routine laparoscopic procedures were prospectively enrolled. Two rounds of direct portal pressure assessments were performed, at insufflation pressures of 0, 6, 10, and 14 mmHg in a predetermined randomized sequence. The data were analyzed for effects of insufflation pressure, hemodynamic alterations, and insufflation round. A best-fit model of the relationship between portal pressure and insufflation pressure was created. Portal pressure increased by 38% at 6 mmHg, 95% at 10 mmHg, and 175% at 14 mmHg compared to baseline. Portal pressure increased exponentially to insufflation pressure at an average rate of 7.45% per mmHg. There was no effect of weight, ratio of weight to insufflation pressure, or insufflation round. No systemic hemodynamic adverse events were observed. Our hypothesis of a direct linear relationship between portal pressure and insufflation pressure was rejected. The exponential increase in portal pressure supports the use of the minimum insufflation pressure to allow visualization during laparoscopy. The return of portal pressure to baseline following de-sufflation supports the comparison of portal pressure measurements before and after laparoscopic shunt attenuation.
