Low-dose ketamine vs morphine for acute pain in the ED: a randomized controlled trial

Joshua P Miller, Steven G Schauer, Victoria J Ganem, Vikhyat S Bebarta
American Journal of Emergency Medicine 2015, 33 (3): 402-8

OBJECTIVES: To compare the maximum change in numeric rating scale (NRS) pain scores, in patients receiving low-dose ketamine (LDK) or morphine (MOR) for acute pain in the emergency department.

METHODS: We performed an institutional review board-approved, randomized, prospective, double-blinded trial at a tertiary, level 1 trauma center. A convenience sample of patients aged 18 to 59 years with acute abdominal, flank, low back, or extremity pain were enrolled. Subjects were consented and randomized to intravenous LDK (0.3mg/kg) or intravenous MOR (0.1mg/kg). Our primary outcome was the maximum change in NRS scores. A sample size of 20 subjects per group was calculated based on an 80% power to detect a 2-point change in NRS scores between treatment groups with estimated SDs of 2 and an α of .05, using a repeated-measures linear model.

RESULTS: Forty-five subjects were enrolled (MOR 21, LDK 24). Demographic variables and baseline NRS scores (7.1 vs 7.1) were similar. Ketamine was not superior to MOR in the maximum change of NRS pain scores, MOR=5 (confidence interval, 6.6-3.5) and LDK=4.9 (confidence interval, 5.8-4). The time to achieve maximum reduction in NRS pain scores was at 5 minutes for LDK and 100 minutes for MOR. Vital signs, adverse events, provider, and nurse satisfaction scores were similar between groups.

CONCLUSION: Low-dose ketamine did not produce a greater reduction in NRS pain scores compared with MOR for acute pain in the emergency department. However, LDK induced a significant analgesic effect within 5 minutes and provided a moderate reduction in pain for 2 hours.

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Chris Ennis

For an ambulance service that has recently introduced ketamine as an analgesic, if less than 2 point reduction in pain score is achieved post 15mg of morphine, these result will support efforts to allow earlier use of ketamine and may reduce scene times in significant trauma.


Dennis Hines Jr

findings are consistent with other findings in that ketamine works quickly. In the arena of military action Israel medics used ketamine on a routine basis.


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