Hemodynamic and arterial blood gas changes during carbon dioxide and helium pneumoperitoneum in pigs

The effects of pneumoperitoneum with carbon dioxide and helium on systemic hemodynamics and arterial blood gases were investigated in pigs in an attempt to clarify the mechanisms by which pneumoperitoneum may induce organ dysfunction. A total of 16 anesthetized female pigs underwent pneumoperitoneum with carbon dioxide or helium (n=8 each) in a stepwise fashion to intraabdominal pressures of 8, 10, 12, 16, and 20 mmHg. Changes in cardiac output; renal and hepatic blood flow; mean arterial, mean pulmonary arterial, mean pulmonary arterial wedge, inferior vena caval, and portal venous pressures; and total peripheral resistance were measured. Arterial blood samples were obtained at the same time the above parameters were determined. Urine volume was measured as an indicator of renal function. Pneumoperitoneum with either carbon dioxide or helium significantly increased venous pressures and simultaneously decreased cardiac output. These changes were associated with decreases in organ blood flow due to increased peripheral resistance. Urinary output was reduced to a similar degree in the two groups. Blood gas analysis revealed pneumoperitoneum-induced metabolic acidosis in both groups, although hypercapnia was observed only in the carbon dioxide group. These findings suggest that pneumoperitoneum-related organ dysfunction may be due to increased intraperitoneal pressure rather than to hypercapnia.