Comparative study between preoperative ketamine bolus dose versus ketamine bolus plus infusion for perioperative analgesia in orthopedic surgery

Background and aim Postoperative pain severity depends on patient factors, anesthesia-related factors, and type of surgery. Pain after orthopedic surgery has been found to be immediate and severe, which necessitates more attention for its management. The aim of this study was assessment of the effectiveness of intravenous ketamine to provide postoperative analgesia after orthopedic surgery. This randomized double-blind study had been performed in Al-Zahraa University Hospital from December 2019 to October 2020. Patients and methods A total of 75 patients subjected to major orthopedic surgery were registered in the study. The patients had been randomly assigned into three equal groups (control, bolus, and bolus with infusion groups) to receive intravenous ketamine bolus dose alone (0.3 mg/kg) (bolus group); ketamine bolus (0.3 mg/kg) plus infusion (5 µg/kg/min), which terminated at the end of operation (bolus with infusion group); or placebo in the form of normal saline (control group). Visual analog pain scale score, postoperative 24 h morphine requirements, time to first analgesic requirement, and postoperative adverse effects were recorded and compared. Results Postoperative visual analog pain scale score and total morphine requirements were significantly less in bolus with infusion group, followed by bolus group, whereas the highest score and requirements were in control group. Regarding the time to first analgesic requirement, there was a statistically significant increased time to first analgesic in bolus with infusion group, followed by bolus group, whereas the shortest time was in control group, and there were nonsignificant differences among groups regarding postoperative complications. Conclusion Ketamine bolus dose alone before skin incision or followed by infusion had the capability of decreasing postoperative pain and total analgesic requirement and increasing the time to first analgesic requirement after orthopedic surgery, with superiority of ketamine bolus dose plus infusion without increasing the incidence of adverse effects.