Acetazolamide Reduces Post Operative Pain Following Laparoscopic Inguinal Herniorrhaphy

Irene Pourladian, BS, Matthew Frelich, MS, Alex Lois, BS, Harvey Woehlck, MD, Michelle Weber, MSN, Andrew Kastenmeier, MD, PhD, Jon C Gould, MD, Matthew I Goldblatt, MD. Medical College Of Wisconsin

Introduction: Carbon dioxide (CO2) is the preferred gas for abdominal insufflation during laparoscopic inguinal herniorrhaphy. Carbonic acid accumulation, which results from CO2 insufflation, can produce abdominal and referred pain in the postoperative setting. Acetazolamide inhibits carbonic anhydrase, an enzyme that increases carbonic acid formation. We hypothesized that post-operative pain after laparoscopic herniorrhaphy will be decreased with the administration of preoperative acetazolamide.

Methods: This study is a retrospective review of patients who underwent laparoscopic pre-peritoneal inguinal herniorrhaphy at the Medical College of Wisconsin between October 2012 and September 2014. Beginning in January 2014, patients received 250mg of acetazolamide preoperatively, while prior to then, the patients did not. The Visual Analog Scale (range, 0-10) was used to measure pain before surgery, in the recovery room, prior to discharge, and the day after surgery by phone call. Cumulative opioids administered post-operatively were measured in morphine equivalents.

Results: A total of 66 patients (9, 17% female) underwent laparoscopic inguinal herniorrhaphy during the study interval. Of these, 22 (33%) patients received acetazolamide preoperatively and 44 (67%) patients were included as controls. Patient demographics, comorbidities and surgical technique did not differ significantly between the two groups. The mean patient age was 52.15 (±13.3) years with a mean BMI of 26.3 (±3.7) kg/m2. Mean pain scores in the recovery room were significantly lower for the acetazolamide group (0.6±1.2), than the control group, (1.9±2.3), p=0.01 (table). Mean pain scores the day after surgery were significantly lower for the acetazolamide group (2.3±0.9), than the control group, (4.0±2.1), p=0.04. Mean cumulative pain scores from emergence from surgery until discharge were significantly lower for the acetazolamide group (1.9±1.5), than the control group, (3.0±2.2), p=0.04. There was no difference in pain scores prior to surgery and immediately prior to discharge. The amount of opioids administered to manage post-operative pain was significantly less for the acetazolamide group (4.3mg±4.8) than the control group (8.9mg±8.4), p=0.04. Complications up to two weeks after surgery, including seroma and urinary retention, did not differ between the groups (p=0.65).

Results of Visual Analog Scale pain surveys, reported as Mean (±SD). *p value < 0.05 is considered significant.
Acetazolamide Group Control Group P-Value
Before Surgery 1.56 (2.81) 0.93 (1.66) 0.28
In Recovery Room 0.59 (1.18) 1.93 (2.31) 0.01*
Prior to Discharge 2.32 (2.08) 3.43 (2.43) 0.07
Day After Surgery 2.25 (0.87) 4.0 (2.12) 0.04*
Mean In-Hospital Pain 1.87 (1.45) 2.9 (2.15) 0.04*

Conclusions: Acetazolamide reduces pain in the immediate post-operative setting. This pain relief continues until the following day. Patients who receive acetazolamide require fewer narcotics for pain management prior to discharge. Acetazolamide is an inexpensive and safe adjunct to treat post-operative pain after laparoscopic inguinal hernia.

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