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 (CO2) and nitrous oxide (N2O) 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 CO2 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 CO2 group. PWP, CVP, PAP, and HR increased slightly in both groups, but there was no significant difference between the groups. The end-tidal CO2 increased in the CO2 group but decreased from the baseline in the N2O group. A significant acidosis was observed in only the CO2 group. PaCO2 significantly increased in the CO2 group; hence, PaCO2 slightly decreased in N2O group. The difference between the groups was significant. Conclusions: N2O insufflation of the extraperitoneal space in dogs avoided the unwanted metabolic and hemodynamic side effects of CO2 insufflation. Thus, N2O insufflation in the extraperitoneal space is a safer alternative to CO2 insufflation experimentally, and can be preferred especially in patients with cardiac and pulmonary diseases.