Efficacy of Low-Dose Ketamine Infusions versus Standard Opioid Analgesia for Postoperative Pain Management in Major Abdominal Surgery

International Journal of Medicine and Medical Sciences | Vol. 16, No. 6, April 2026 | pp. 41–48

DOI: 10.46882/2026/IJMMS/160041

Original Research Article

Efficacy of Low-Dose Ketamine Infusions versus Standard Opioid Analgesia for Postoperative Pain Management in Major Abdominal Surgery

Charles O. Igwe¹, Rachel L. Sanon², Anthony D. Boateng¹*

¹Department of Anesthesiology and Intensive Care, Faculty of Clinical Sciences, College of Health Sciences, University of Abuja, Abuja, Nigeria.

²Department of Surgery, Faculty of Health Sciences, Université de Ouagadougou, Ouagadougou, Burkina Faso.

Abstract:

Postoperative pain management following major open abdominal procedures frequently relies on high-dose opioid regimens, which are associated with adverse outcomes such as respiratory depression, ileus, and prolonged recovery times. This randomized, open-label, comparative clinical trial evaluated the therapeutic efficacy, safety, and opioid-sparing capacity of low-dose intraoperative and postoperative ketamine infusions compared to standard patient-controlled opioid analgesia. A total of 140 adult patients scheduled for major elective open laparotomies were randomly assigned to receive either an intravenous ketamine bolus (0.25 mg/kg) followed by continuous infusion (0.125 mg/kg/h) until 24 hours post-surgery (n = 70) or standard intravenous morphine patient-controlled analgesia (n = 70). The primary outcomes were total cumulative morphine consumption at 24 and 48 hours, and visual analog scale (VAS) pain scores. Patients in the ketamine cohort demonstrated a highly significant 38.5% reduction in total morphine consumption at 24 hours (mean = 24.5 ± 4.2 mg) compared to the control group (mean = 39.8 ± 6.4 mg, p < 0.001). Mean VAS pain scores at rest and during coughing were significantly lower in the ketamine arm across the first 12 hours post-surgery (p < 0.01). Furthermore, the incidence of postoperative opioid-induced nausea and vomiting was significantly lower in the ketamine group (8.6% vs. 24.3%, p < 0.05), and the mean time to first flatus was shortened by 8.2 hours (p < 0.01). Low-dose perioperative ketamine infusions provide effective analgesia and demonstrate a significant opioid-sparing effect, leading to fewer opioid-related side effects and promoting faster gastrointestinal recovery after major abdominal surgery.

Keywords: Ketamine Infusion, Postoperative Pain, Opioid Analgesia, Opioid-Sparing Effect, Major Laparotomy, Gastrointestinal Recovery

Manuscript Timeline: Received: March 10, 2026; Revised: April 19, 2026; Accepted: April 12, 2026; Published: April 15, 2026.

Citation: Igwe CO, Sanon RL, Boateng AD. Efficacy of Low-Dose Ketamine Infusions versus Standard Opioid Analgesia for Postoperative Pain Management in Major Abdominal Surgery. International Journal of Medicine and Medical Sciences, 2026, 16(6): 41–48. DOI: 10.46882/2026/IJMMS/160041

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