Acetazolamide reduces postoperative pain following laparoscopic inguinal herniorrhaphy

Background Carbonic acid accumulation, which results from CO 2 insufflation, can produce visceral and referred pain in the postoperative setting. Acetazolamide inhibits carbonic anhydrase, an enzyme that accelerates carbonic acid formation. We hypothesized that preoperative administration of acetazolamide would decrease postoperative pain in patients undergoing laparoscopic inguinal herniorrhaphy. Methods A retrospective review was conducted of patients who underwent laparoscopic preperitoneal inguinal herniorrhaphy at the Medical College of Wisconsin between October 2012 and September 2014. Beginning in January 2014, patients began receiving 250 mg of acetazolamide preoperatively; patients prior to that time did not. The visual analog scale (range 0–10) was used to assess both preoperative pain and postoperative pain. Results A total of 66 patients underwent laparoscopic inguinal herniorrhaphy during the study interval. Of these, 22 (33 %) patients received acetazolamide preoperatively, and 44 (67 %) were included as controls. Overall mean pain scores were lower in the acetazolamide group (1.9 ± 1.45 vs 2.9 ± 1.5, p = 0.04). Specifically, patients who received acetazolamide reported lower pain scores immediately after surgery (0.6 ± 1.2 vs 1.9 ± 2.3, p = 0.01) and on post-op day one (2.3 ± 0.9 vs 4.0 ± 2.1, p = 0.04). Total morphine equivalents administered to manage postoperative pain were significantly less for the acetazolamide group (4.3 ± 4.8 mg) when compared to the control group (8.9 ± 8.4 mg), p = 0.04. Perioperative complications did not differ between the groups ( p = 0.16). Conclusions Acetazolamide appears to reduce pain in the immediate postoperative setting. Patients who received acetazolamide had lower pain scores postoperatively and required fewer narcotics for pain management prior to discharge.