Supplementary Material for: Use of acetylcholinesterase inhibitors in reducing time to gastrointestinal function recovery following abdominal surgery: A systematic review.

Introduction: Postoperative ileus (POI) is a significant complication following abdominal surgery, increasing morbidity and mortality. The cholinergic anti-inflammatory response is one of the major pathways involved in developing POI, but current recommendations to prevent POI do not target this. This review aims to summarise evidence for the use of acetylcholinesterase inhibitors, neostigmine and pyridostigmine, to reduce the time to return of gastrointestinal function (GI) following abdominal surgery.

Methods: A systematic search of various databases was performed from 1946 to May 2023. Randomised controlled trials (RCT) on acetylcholinesterase inhibitors in intra-abdominal surgery were included. Data on time to flatus and/or stool and side effects were extracted.

Results: Among 776 screened manuscripts, 8 RCTs (703 patients) investigating acetylcholinesterase inhibitors, in intra-abdominal surgery were analysed. Five studies showed a significant reduction in time to flatus and/or stool by 17-47.6 hours. Methodological variations, differing procedure types, and potential bias were observed. Limited studies reported side effects or length of stay.

Conclusion: Acetylcholinesterase inhibitors may reduce the time for gastrointestinal function to return. However, current evidence is limited and biased. Further studies incorporating acetylcholinesterase inhibitors in an enhanced recovery protocol are required to address this question, especially for patients undergoing colorectal surgery.