Effects of intraabdominal CO 2 insufflation in the piglet

Abstract

Adult intraabdominal surgery performed with the minimal-access technique has created a revolution in surgery. This technique has remained largely unused for pediatric surgical procedures because of concerns regarding its safety and efficacy. Presently, intraabdominal insufflation of CO 2 is the preliminary step to performing minimal access surgery. In this study, an animal model was developed to determine the effects of intraabdominal CO 2 insufflation in the infant. Eight piglets (4 to 6 kg; 14 to 19 days of age) were instrumented under fentanyl anesthesia to allow measurement of arterial blood pressure (BP), central venous pressure (CVP), heart rate (HR), cardiac index (CI), inferior vena cava pressure (IVCp), inferior vena cava flow (IVCf), mediastinal pressure (Mp), partial pressure of CO 2 (Pa co 2 ), and minute ventilation (V E) at baseline and during 1 hour of CO 2 insufflation to a pressure of 15 mm Hg and again when ventilation was increased to control Paco 2 levels. Continuous recording of data allowed time-course analysis of 15-minute blocks to determine the rate of change of measured variables. A second group of 6 piglets (4 to 6 kg) underwent the same instrumentation, but their baseline values were compared with those during N 2O insufflation to isolate the effects of increased intraabdominal pressure. During CO 2 insufflation alone, Paco 2 increased by 31% ( P < .0001). This increase occurred within the first 15 minutes of insufflation and then remained stable. The increase was likely the result of increased CO 2 absorption from the peritoneal cavity because V E was unchanged. CO 2 insufflation alone was associated with increases of 10% in CI ( P = .02), 29% in CVP ( P = .01), and 17% in BP ( P < .0001), and no change in systemic vascular resistance (SVR) and IVCf. In contrast, when Paco 2 was controlled by increased ventilation, there was no significant change in CI, increases of 7% in SVR ( P = .02), 57% in CVP ( P = .001), and 7% in BP ( P = .01), and a 22% decrease in IVCf ( P = .04). N 2O insufflation resulted in no significant change in CI, increases of 22% in SVR ( P = .01), 35% in CVP ( P = .01), and 16% in BP ( P = .005), and a 25% decrease in IVCf ( P = .02). CO 2 insufflation is associated with significant CO 2 absorption and increased myocardial work in the piglet model.