Acidification during carbon dioxide pneumoperitoneum is restricted to the gas-exposed peritoneal surface: effects of pressure, gas flow, and additional intraperitoneal fluids

BACKGROUND: There are varying data regarding the degree and extent of abdominal acidification during laparoscopy. The aim of this study was to determine the extent of peritoneal acidification during carbon dioxide insufflation and the effects of different pressures, insufflation rates, and free intraperitoneal fluids. MATERIALS AND METHODS: Sixteen male Sprague-Dawley rats weighing 250-300 g were anesthetized and a two-point pH probe was inserted in the abdominal cavity. After closure of the abdominal wall, each group of 4 rats was subjected to one of four insufflation regimens: low pressure (2 mm Hg, no leakage); high pressure (10 mm Hg, no leakage); leakage (2 mm Hg, leakage 0.5 mL/min); and fluid (2 mm Hg, 10 mL intraperitoneal 0.9% NaCl). During insufflation peritoneal pH was continuously measured. RESULTS: Carbon dioxide insufflation significantly decreased the peritoneal pH to <7.0 only in areas exposed to the insufflation gas. Neither changes in pressure nor insufflation rate had major effects on the peritoneal pH. The addition of 10 mL normal saline into the abdominal cavity significantly enhanced the pH change during insufflation. conclusion: Acidification associated with carbon dioxide pneumoperitoneum is limited to the area of inspection and manipulation. The increased acidification following injection of normal saline could offer a useful mechanism to alter the inflammatory response.