A comparison of the hemodynamic and metabolic effects of extraperitoneal carbon dioxide and nitrous oxide insufflation

Background: The aim of the present study was to compare the hemodynamic and metabolic effects of extraperitoneal carbon dioxide (CO 2) and nitrous oxide (N 2O) insufflation. Material and methods: Fourteen dogs were used in the experiment. All the animals were intubated under general anesthesia. A catheter was placed into the right juguler vein for central venous pressure (CVP), pulmonary artery pressure (PAP), pulmonary wedge pressure (PWP), and heart rate (HR) monitorization. End-tidal CO 2 pressure was measured by a capnometer connected to the endotracheal tube. Another catheter was inserted into the left femoral artery for arterial blood gas analysis and blood pressure monitorization. The preperitoneal dissection was made from a 1.5 cm subumbilical incision by using a preperitoneal dissection balloon. A laparoscope was placed in the preperitoneal space and the gas insufflation was kept at a constant pressure of 12 mm Hg throughout the experiment. All the study parameters were measured at the beginning of the insufflation and at every 15 minutes for 1 hour. Results: Mean artery pressure increased with time in both groups, but the increase was only significant in the CO 2 group. PWP, CVP, PAP, and HR increased slightly in both groups, but there was no significant difference between the groups. The end-tidal CO 2 increased in the CO 2 group but decreased from the baseline in the N 2O group. A significant acidosis was observed in only the CO 2 group. PaCO 2 significantly increased in the CO 2 group; hence, PaCO 2 slightly decreased in N 2O group. The difference between the groups was significant. Conclusions: N 2O insufflation of the extraperitoneal space in dogs avoided the unwanted metabolic and hemodynamic side effects of CO 2 insufflation. Thus, N 2O insufflation in the extraperitoneal space is a safer alternative to CO 2 insufflation experimentally, and can be preferred especially in patients with cardiac and pulmonary diseases.