Ketamine versus Morphine
Intravenous subdissociative-dose Ketamine versus Morphine for analgesia in the Emergency Department: A Randomized Controlled Trial. Motov, S, Rockoff, B, et al. Ann Emerg Med. (2015).
Ketamine is a non-competitive N-methyl-D-aspartate and glutamate receptor antagonist that blocks the release of excitatory neurotransmitter glutamate providing anesthesia, amnesia, and analgesia. In subdissociative doses, ketamine has shown to provide effective analgesia. This study compared the analgesic efficacy and safety of subdissociative intravenous dose ketamine with morphine in the ED.
This was a randomized, controlled, double blind trial involving 90 ED patients with acute abdominal, flank, or musculoskeletal painthat were either treated with subdissociative-dose of intravenous ketamine (0.3mg/kg) or morphine (0.1 mg/kg). Pain scores and adverse effects were recorded at 15, 30, 60, 90, and 120 minutes. Fentanyl was provided as a rescue medication for those requiring additional pain relief. Primary outcome studied was comparative reduction of numeric rating scale pain scores between recipients of ketamine and morphine at 30 mins and secondary outcome was need for rescue analgesia at either 30 or 60 mins
The primary change in mean pain scores was not significantly different in the ketamine and morphine groups At 15 minutes, more patients reported complete resolution of pain in the ketamine group but this difference was no longer present at 30 mins. There was also no difference in the incidence of rescue fentanyl analgesia at 30 or 60 minutes but was required by 17% more ketamine recipients than morphine recipients at 120 minutes. No serious adverse events occurred in either group but patients in the ketamine group did report increased minor adverse effects at 15 mins post drug administration including disorientation, dizziness, nausea, and mood changes but not at 30 minutes.
Although this was a single center study and there was potential for unblinding, the study did introduce another analgesic that we can add to our armamentarium. Perhaps it may not be the first medication to reach for to treat analgesia but certainly should be considered in patients that do not have any relief with opiates.