Effect of intraperitoneal CO2 concentration on postoperative pain after laparoscopic cholecystectomy

PURPOSEThis study set out to identify the association between the intraperitoneal CO2 concentrations and postoperative pain by dividing the participants into a control group and 2 experimental groups receiving irrigation (1 L and 2 L), and directly measuring their intraperitoneal CO2 concentrations with a CO2 gas detector. METHODSA total of 101 patients, American Society of Anesthesiologists physical status classification I and II patients aged 18-65 years were enrolled in the study. Group 1 did not receive irrigation with normal saline, while groups 2 and 3 were administered irrigation with 1 L and 2 L of normal saline, respectively, after laparoscopic cholecystectomy. Intraperitoneal CO2 concentrations were measured with a CO2 gas detector through the port, and postoperative pain was assessed on a visual analogue scale at 6, 12, and 24 hours after surgery. RESULTSThe intraperitoneal CO2 concentrations were 1,016.0 ± 960.3 ppm in group 1, 524.5 ± 383.2 ppm in group 2, and 362.2 ± 293.6 ppm in group 3, showing significantly lower concentrations in groups 2 and 3. Postoperative pain was significantly lower in group 3 at 6 hours after surgery, and in groups 2 and 3 at 12 hours after the surgery. However, there was no significant difference between the 3 groups in postoperative pain 24 hours after the surgery. CONCLUSIONThis study found a causal relationship between the amount of normal saline used for irrigation and the intraperitoneal CO2 concentrations in that irrigation with normal saline reduces pain on the day of the surgery.