Ketamine as a component of multimodal analgesia for pain management in bariatric surgery: A systematic review and meta-analysis of randomized controlled trials

Introduction: Anaesthesia in morbidly obese people is challenging with a high dose of opioid consumption. This systematic review and meta-analysis of randomised controlled trials (RCTs) summaries evidence comparing ketamine to placebo for pain management after bariatric surgery. Methods: We used PRISMA 2020 and AMSTAR 2 guidelines to conduct this study. The random-effects model was adopted using Review Manager Version 5.3 for pooled estimates. Results: Seven RCTs published between 2009 and 2021 were eligible, including a total of 412 patients (202 patients in the ketamine group and 210 patients in the control group). In the ketamine group total opioid consumption during the first 24 h postoperatively was reduced (mean difference, MD = -5.89; 95% CI [-10.39, -1.38], p = 0.01), lower pain score at 4 h (MD = -0.81; 95% CI [-1.52,-0.10], p = 0.03), pain score at 8 h (MD = -1.00; 95% CI [-1.21, -0.79], p < 0.01), and shorter hospital stay (MD = -0.10; 95% CI [-0.20, -0.01], p = 0.03). There was no significant difference between the two groups regarding duration of anaesthesia (MD = -3.42; 95% CI [-8.62, 1.82], p = 0.20), or sedation score (MD = -0.02; 95% CI [-0.21, 0.17], p = 0.84). As concern the postoperative complications, risks of postoperative nausea and vomiting(OR = 0.75; 95% CI [0.27, 2.04], p = 0.56), hallucinations (OR = 5.47; 95% CI [0.26, 117.23], p = 0.28), dizziness (OR = 1.05; 95% CI [0.14, 7.78], p = 0.96), and euphoria (OR = 5.77; 95% CI [0.65, 51.52], p = 0.12) were not different between the two groups either. Conclusion: Ketamine could be an effective and safe technique for pain management following bariatric surgery. It reduces opioid consumption, postoperative pain, and hospital stay.