The effect of intraoperative low-dose ketamine versus dexmedetomidine infusion on postoperative bowel recovery in patients undergoing gastrointestinal malignancy surgeries: Placebo-controlled, randomized trial

No studies have compared the effects of ketamine and dexmedetomidine on bowel recovery. We evaluated the effects of intraoperative low-dose ketamine or dexmedetomidine infusion on postoperative bowel recovery in patients undergoing gastrointestinal (GI) malignancy surgeries. This placebo-controlled, randomized study was carried out in 84 American Society of Anesthesiologists II patients, aged 18–70 years, of either gender, undergoing elective open GI malignancy surgeries. Patients received intraoperative infusion of ketamine @ 0.1 mg kg-1 h-1 (KET), dexmedetomidine @ 0.25 μg kg-1 h-1 (DEX), or normal saline (placebo). Primary outcome was the time to first flatus and/or stool. Secondary outcomes included time to extubation, total analgesic requirement, postoperative pain scores, time to feeds, duration of intensive care unit (ICU) and hospital stay, and the incidence of adverse events. Continuous data were analyzed by the one-way analysis of variance (ANOVA) or the Kruskal–Wallis test. Categorical data were analyzed by the Chi-square test or the Fisher’s exact test. Median time to passage of flatus and/or stool was 3 [interquartile range (IQR) 2–3] days in the KET group, 2 [IQR 2–3] days in the DEX group, and 2 [IQR 2–3] days in the placebo group (P = 0.53 for placebo vs. KET, 0.81 for placebo vs. DEX, and 0.99 for KET vs. DEX). Pain scores and analgesic consumption were significantly less in the intervention groups versus placebo (P < 0.001). No difference was seen in other secondary outcomes. Low-dose ketamine or dexmedetomidine did not result in early bowel recovery despite lower pain scores and opioid consumption in patients undergoing open GI malignancy surgeries. Key Message: What is known: Ketamine and dexmedetomidine may promote bowel recovery by improving analgesia and decreasing opioid usage.Main findings: This randomized controlled trial found no evidence of earlier bowel recovery with ketamine or dexmedetomidine versus placebo despite lower pain scores and analgesic consumption in the ketamine and dexmedetomidine groups.