Effects of Pneumoperitoneum With Carbon Dioxide, Argon, or Helium on Hemodynamic and Respiratory Function

OBJECTIVE: To evaluate the effects of pneumoperitoneum with carbon dioxide, argon, and helium; different abdominal pressures (ie, 8, 12, and 16 mm Hg); and different positions (ie, head up, head down, supine) on hemodynamic and respiratory function in a porcine model. DESIGN: Prospective randomized trial. SETTING: Animal research laboratory. ANIMALS: Eighteen pigs weighing 25.5 +/- 6.9 kg (mean +/- SD). INTERVENTIONS: General anesthesia with endotracheal intubation. Implantation of pulmonal artery catheter and central venous line in jugular vein and catheters in femoral artery and vein. Carbon dioxide, argon, or helium was insufflated through a cannula in the left upper quadrant. The type of gas was randomly assigned to each animal. After recording baseline values at the beginning and at the end without pneumoperitoneum, each animal was placed in 1 of the 3 positions and under 1 of the 3 pressures kept by the insufflator. After 15 minutes of adaptation to the new circumstances, all factors were recorded. This procedure was repeated until all 9 combinations of pressures and positions were evaluated. MAIN OUTCOME MEASURES: Cardiac output; heart rate; stroke volume; right ventricular stroke work; pressures in the pulmonal artery, vena cava, and femoral artery and vein; systemic vascular resistance; respiratory pressure; tidal volume; pH; base excess; oxygen partial pressure; and carbon dioxide partial pressure. RESULTS: The type of gas did not affect cardiac output. Only carbon dioxide demonstrated negative effects on respiratory function. Argon markedly increased afterload. Carbon dioxide increased central venous and mean arterial pressure, which was only moderate using helium. A head-up position decreased cardiac output and central venous pressure and increased mean arterial and peripheral venous pressures, which were partly compensated in a head-down position. An intraperitoneal pressure of 16 mm Hg increased peripheral and central venous pressures, heart rate, and respiratory pressure, and decreased cardiac output, tidal volume, and pH. CONCLUSIONS: Helium may be an alternative gas to establish pneumoperitoneum because it does not have any effect on respiratory function and has only a moderate effect on hemodynamic function. Argon insufflation has some hemodynamic disadvantages. An intraperitoneal pressure greater than 12 mm Hg and a head-up position should be avoided because both have a markedly negative effect on respiratory and hemodynamic factors.