Comparison of the efficacy of bolus low-dose ketamine versus bolus plus infusion low-dose ketamine on pain management in emergency departments: a randomized clinical trial

Abstract

Objective Ketamine shows promise as an analgesic in emergency medicine, but its frequent side effects limit its broader adoption. We proposed that administering a ketamine bolus followed by an infusion would offer more consistent and prolonged pain relief, with fewer side effects, compared to a bolus-only approach. Methods In this double-blind clinical trial, trauma patients with a numeric rating scale pain score of 6 or higher were randomly assigned to two groups. The bolus-only group received 0.3 mg/kg of ketamine over 1 minute, followed by a 30-minute infusion of 0.9 saline. The bolus-and-infusion group received 0.15 mg/kg of ketamine over 1 minute, followed by a 30-minute infusion of 0.15 mg/kg ketamine. The primary outcome was the average reduction in pain scores. Results A total of 80 patients participated, with 77 included in the final analysis. Both groups experienced a significant reduction in pain scores (all P<0.001). After 30 minutes, the bolus-and-infusion group consistently reported lower pain scores and required less rescue analgesia, though these differences were not statistically significant. Vital signs remained stable in both groups, and there were no statistically significant differences in side effects between the groups (P>0.05). Conclusion Both ketamine administration strategies provided significant pain relief. There were no statistically significant differences between the groups regarding analgesic efficacy or side effect profiles.