Comparison of Intravenous Acetaminophen and Ketorolac for Postoperative Pain Relief After Elective Midline Laparotomy: A Prospective Non-randomized Comparative Study

BackgroundPostoperative pain is a common concern following elective midline laparotomy and may impair coughing, deep breathing, early mobilization, and postoperative recovery.Effective analgesia is essential to improve patient comfort and facilitate recovery while minimizing adverse effects.Intravenous acetaminophen and ketorolac are non-opioid analgesics with different mechanisms of action and safety profiles.Comparing these medications may help inform analgesic selection in patients undergoing elective open abdominal surgery. ObjectiveThe aim of this study is to compare the analgesic effectiveness and safety of intravenous acetaminophen and intravenous ketorolac in adult patients undergoing elective open abdominal surgery through a midline incision, with the primary outcome being the numerical rating scale (NRS) pain score at two hours postoperatively. MethodsA prospective, non-randomized comparative study was conducted among 114 adults undergoing elective open abdominal surgery through a midline incision at the Department of Anesthesia, Bangladesh Medical University (BMU), Dhaka, Bangladesh.Patients were allocated according to the analgesic regimen selected by the treating anesthesiologist to receive either intravenous acetaminophen (Group A, n = 57) or intravenous ketorolac (Group K, n = 57).The primary outcome was the NRS pain score at two hours postoperatively.Secondary outcomes included pain scores at other postoperative time points, rescue analgesia requirements, time to first rescue analgesia, and adverse events during the first 24 postoperative hours.Between-group differences were analyzed using appropriate statistical tests, with a two-sided p-value of less than 0.05 considered statistically significant. ResultsThe mean NRS pain score at two hours postoperatively was significantly lower in Group K than in Group A (3.6 ± 1.6 vs. 4.6 ± 1.6; mean difference, 1.0 point; 95% confidence interval, 0.43-1.57;p = 0.001).Pain scores were also significantly lower in Group K at one, four, and six hours postoperatively, whereas no significant differences were observed at 12 or 24 hours.Rescue analgesia was required by fewer patients in Group K than in Group A (27/57 (47.4%) vs. 39/57 (68.4%); p = 0.023).The median time to first rescue analgesia was longer in Group K (180 minutes (interquartile range (IQR), 90-360)) than in Group A (120 minutes (IQR, 60-240); p = 0.040).The mean number of rescue analgesic doses was also lower in Group K (0.9 ± 0.8 vs. 1.3 ± 0.9; p = 0.015).Nausea and/or vomiting occurred in 15.8% of patients in Group K and 19.3% in Group A (p = 0.622).No clinically significant bleeding, acute kidney injury, or serious adverse events were recorded in either group during the 24-hour observation period.The findings suggest better early postoperative analgesia with ketorolac; however, the non-randomized design and short follow-up limit causal interpretation and conclusions regarding comparative safety. ConclusionThis prospective comparative study evaluated intravenous acetaminophen and ketorolac for postoperative pain management after elective midline laparotomy.The results favor ketorolac for early pain control, but comparative effectiveness must be established using observed patient data and appropriate adjustment for confounding.