Influence of pneumoperitoneum and postural change on the cardiovascular and respiratory systems in dogs

Abstract

We investigated the influence of pneumoperitoneum#(PP) and postural change under inhalation anesthesia with isoflurane, which is routinely used in dogs, on the cardiovascular and respiratory systems. As test animals, 6 adult beagles were used. To induce anesthesia, atropine, butorphanol and propofol were intravenously injected. Anesthesia was maintained with 1.3 MAC (1.7%) isoflurane. The following were the experiment conditions: I:E ratio, 1:1.9; tidal air exchange, 20 ml/kg; and ventilation frequency, 14 times/min. Respiration was regulated so that the PaCO₂ was approximately 35 to 40 mmHg before the start of the experiment. PP with CO₂ (intraperitoneal pressure 15 mmHg) and a postural change (15 degrees) was performed during the experiment. As parameters of circulatory kinetics, heart rate (HR), mean aortic pressure (MAP), mean pulmonary arterial pressure (MPAP), central venous pressure (CVP), femoral venous pressure (FVP), and cardiac output (CO) were measured. As parameters of respiratory kinetics, airway pressure (PAW) and blood gas (BG) were measured. There were significant increases in HR, MAP, MPAP, CVP, FVP, CO, PAW and PaCO₂ after PP in the horizontal position. There were significant increases in CVP, FVP, PAW and PaCO₂ after PP in the Trendelenburg position. There were significant increases in the MPAP, CVP, FVP, PAW and PaCO₂ after PP in the inverse Trendelenburg position. There was a significant difference in FVP after PP between the Trendelenburg position and inverse Trendelenburg position. The results of this experiment suggest that appropriate anesthesia control such as changing the ventilation conditions after PP is required for laparoscopic surgery under inhalation anesthesia with isoflurane.