Use by Paramedics of Intranasal Ketamine Plus Nitrous Oxide May Alleviate Acute Pain

The addition of intranasal ketamine, administered by paramedics, to usual treatment with nitrous oxide was found to alleviate acute pain and improve comfort within 30 minutes, according to a study published in the Annals of Emergency Medicine.

Researchers conducted a randomized double-blind study of 120 out-of-hospital patients (aged ≥18; median age, 54) with acute pain (ie, verbal numeric rating scale [VNRS] pain score ≥5). The primary study outcome was a reduction in VNRS pain score ≥2 points (deemed clinically significant), 30 minutes after treatment administration (nitrous oxide plus intranasal ketamine or nitrous oxide plus intranasal placebo; n=60 for both).

All study participants were offered nitrous oxide, per existing paramedic protocols, but 27% and 25% of patients in the intranasal ketamine and placebo groups, respectively did not receive it. A total of 76% vs 41% of patients who received intranasal ketamine vs placebo, respectively reported a ≥2-point reduction in VRNS score at 30 minutes (difference, 35%; 95% CI, 17%-51%). Median VNRS reduction in the intranasal ketamine group was 2.0 and 3.0 at 15 and 30 minutes, respectively, compared with 1.0 and 1.0, respectively, in the placebo group.

In the intranasal ketamine group, 62% of participants reported adverse events compared with 20% in the placebo group (95% CI, 49%-73% and 95% CI, 12%-32%, respectively). However, these adverse events were minor, requiring no intervention.

Study limitations include the use of a single-site location, which may limit generalizability. In addition, as some patients did not receive nitrous oxide, the conclusions drawn regarding the effect of additional ketamine are limited.

“Because [the] use of…opiates is not available to primary care paramedics, they are limited to the use of inhaled nitrous oxide as an analgesic. This results in a significant burden of uncontrolled pain for patients,” noted the study authors. “In this study, primary care paramedics were able to use intranasal ketamine analgesia effectively and with apparent safety.”

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Reference

Andolfatto G, Innes K, Dick W, et al. Prehospital analgesia with intranasal ketamine (PAIN-K): A randomized double-blind trial in adults [published online March 26, 2019]. Ann Emerg Med. doi:10.1016/j.annemergmed.2019.01.048