Hemodynamic effects of argon pneumoperitoneum

The hemodynamic effects of argon pneumoperitoneum were studied to define its possible role as an alternative gas for intraperitoneal insufflation during minimally invasive surgery. Adult pigs were anesthetized and placed on mechanical ventilation. Parameters measured or determined included mean arterial (MAP), pulmonary arterial (PAP), pulmonary arterial wedge (PAWP), right atrial (CVP), and inferior vena cava venous (IVC) pressures, total excretion of CO₂ (VCO₂), oxygen consumption (VO₂), minute ventilation, and arterial blood gases. Also determined were cardiac output, stroke volume, and systemic vascular resistance all indexed to weight (CI, SVI, SVRI). Data were recorded during a 1-h baseline, 2 h of insufflation with argon gas at a constant pressure of 15 mmHg, and 1 h recovery after desufflation. There was no significant change from baseline in VCO₂, VO₂, MAP, PAP, PAWP, CVP, PaCO₂, or arterial pH. Argon pneumoperitoneum significantly increased systemic vascular resistance index and exerted a depressant effect on stroke volume index and cardiac index by 25% and 30% from baseline values, respectively (P<0.05). Inferior vena cava pressure increased as a reflection of the intraabdominal pressure. Argon insufflation had no effect on respiratory function. Argon gas may not be physiologically inert, and in patients with cardiovascular disease its effects may be clinically important.