Intraperitoneal Carbon Dioxide Insufflation and Cardiopulmonary Functions: Laparoscopic Cholecystectomy in Pigs

We studied the effects of laparoscopic cholecystectomy on respiratory and hemodynamic function in eight adult pigs. Minute ventilation was adjusted to normalize baseline arterial blood gases, then fixed throughout carbon dioxide insufflation. A metabolic measurement cart recorded total CO₂ excretion, oxygen consumption, and minute ventilation. Carbon dioxide pneumoperitoneum was maintained at a constant pressure of 15 mm Hg as cholecystectomy was performed. After 1 hour of insufflation, CO₂ excretion increased from 115±10 mL/min to 149±9 mL/min but O₂ consumption remained unchanged. The PaCO₂ increased from 35±2 mm Hg to 49±3 mm Hg and arterial pH fell from 7.47±0.02 to 7.35±0.03. Systemic and pulmonary hypertension occurred and stroke volume dropped from 35.5±3.5 mL to 28.6±2.2 mL with compensatory tachycardia. Right atrial pressure remained unchanged as inferior vena cava pressure increased to reflect the intraperitoneal pressure. We conclude that CO₂ pneumoperitoneum resulted in significant transperitoneal CO₂ absorption, with secondary hypercapnia and acidemia. The accumulation of CO₂ was also associated with an increase in systemic and pulmonary arterial pressure. Heart rate increased to compensate for the decreased stroke volume to maintain cardiac output.