Intravenous Conscious Sedation Use Before and After Gastric Bypass Surgery: A Failure of Weight Based Algorithms

Abstract

Intravenous Conscious Sedation Use Before and After Gastric Bypass Surgery: A Failure of Weight-Based AlgorithmsLee LS, Thompson CC. Background: The obesity epidemic in Western countries has resulted in a sharp rise in weight reduction surgeries. Endoscopies in this patient population are similarly increasing. The aim of this study was to examine medication use and related outcomes during upper endoscopy in obese patients before and after Roux-en-Y gastric bypass surgery. Methods: Retrospective review of patients who underwent upper endoscopies with intravenous conscious sedation before and/ or after Roux-en-Y gastric bypass surgery for obesity was conducted at a single academic institution from 1/2001-3/2005. Preoperatively 56 upper endoscopies had been performed in 46 patients while following surgery, 65 patients had undergone 85 upper endoscopies. Thirteen of the 46 patients in the pre-surgical group had undergone both pre- and post-surgical upper endoscopies. Data regarding indication, medication use, and findings during endoscopy were collected in addition to complications and history of chronic pain medication use and alcohol abuse. Results: One immediate self-limited post-endoscopy complication occurred (1/141, 0.007%). Patients undergoing upper endoscopy before or after surgery were comparable in age (42.7 ± 10.2 vs. 44.5 ± 10.0 years) and gender (40/46 vs. 54/65 female). Pre-operative patients weighed significantly more than the post-operative group at time of endoscopy (270.7 ± 54.5 lbs vs. 199.9 ± 47.7 lbs, p < 0.01). The mean time interval from surgery to post-operative endoscopy was 37.0 ± 31.1 m with a mean weight loss of 97.7 ± 45.7 lbs. The amount of midazolam and fentanyl used during upper endoscopies was significantly greater in post-operative than pre-operative patients: 5.0 ± 1.7 mg vs. 3.8 ± 1.6 mg of midazolam (p < 0.01), 120.0 ± 45.0 mcg vs. 85.6 ± 44.6 mcg of fentanyl (p < 0.01). Only 7 patients in the pre-operative group were on chronic pain medications at the time of endoscopy compared to 6 patients in the postoperative group. Subset analysis of 13 patients who had undergone both pre- and post-operative endoscopy confirmed increased medication use during post-surgical endoscopy: 5.3 ± 2.3 mg vs. 4.3 ± 1.9 mg of midazolam (p = 0.02) and 125.0 ± 63.5 mcg vs. 80.7 ± 54.0 mcg of fentanyl (p = 0.0007). Conclusion: We report the unexpected observation that medication use during upper endoscopy is significantly higher following weight loss from Roux-en-Y gastric bypass surgery. This is clinically significant and may indicate a fundamental change in drug metabolism resulting from the surgery and weight loss in these obese patients.