Ketamine may be a more effective treatment option than opioids for prehospital acute pain, according to findings from a systematic review study published in the BMJ Open. Ketamine likely decreased pain more than opioids, but had a notable higher risk for agitation.
The review included 8 studies comprising a pooled cohort of 2760 adult patients with prehospital acute pain who were treated with either ketamine, opioids, or nitrous oxide. Studies included in this review were 4 randomized controlled trials, 1 cluster randomized trial, 1 prospective cohort study, and 2 retrospective studies.
Across studies, comparisons were made between intravenous (IV) ketamine and IV opioids, IV ketamine with IV morphine vs IV morphine alone, continuous IV ketamine vs single-dose IV ketamine, intranasal ketamine with nitrous oxide vs nitrous oxide alone.
According to the investigators, there were 5 studies in the review that had high risks of bias. In a cluster randomized controlled trial of 308 patients and a retrospective cohort of 158 patients, treatment with ketamine was associated with probable lower pain scores compared with opioids (change in visual analogue scale, −0.4; 95% CI, −0.8-0.0; change in numeric pain rating scale, −3.0; 95% CI, −3.86 to −2.14, respectively) prior to hospitalization.
The researchers also found that treatment with ketamine probably led to less nausea and vomiting compared with opioids (risk ratio [RR], 0.24; 95% CI, 0.11-0.52) but greater agitation (RR, 7.81; 95% CI, 1.85-33).
A limitation of the study, according to the researchers, was the potential lack of other studies that may have generated more relevant results, including studies not published in English. Also, none of the studies included in the review were powered to assess the safety of ketamine in this patient population.
Based on this review, the researchers concluded that treatment with IV ketamine in analgesic doses of 0.1 to 0.2mg/kg “appears to be at least as effective as opioids administered alone considering pain reduction.”
Sandberg M, Hyldmo PK, Kongstad P, et al. Ketamine for the treatment of prehospital acute pain: A systematic review of benefit and harm. BMJ Open. Published online November 24, 2020. doi:10.1136/bmjopen-2020-038134