Acid-base balance alterations in laparoscopic cholecystectomy

Background: The purpose of this study is to determine alterations of acid-base balance originated by pneumoperitoneum with CO2. Influence of other factors such as anes thetic technique, duration of procedure, and volume of CO2 insufflated has also been analyzed. Methods: Some 132 patients were divided in three groups according to anesthetic technique used. Arterial blood gases were determined before pneumoperitoneum, at 20 min after it, and every 30 min, until procedure's end, and in postoperative period up to a total of four samples. Results: Pneumoperitoneum originated a fall of pH (p < 0.001), ion bicarbonate (p < 0.001), and base excess (p < 0.001) and an elevation of PaCO2, (p < 0.001). No correlation was found between these changes and duration of pneumoperitoneum or amount of CO2 insufflated. Changes were fundamentally of a metabolic type. There were no statistically significant differences among anesthetic techniques. Conclusions: In conclusion, pneumoperitoneum with CO2 originates alterations of the acid-base balance, mostly of a metabolic type. This could mean that besides CO2 absorption, there is a tissular hypoperfusion due to the increase of abdominal pressure.