Ketamine use as out-of-hospital analgesia

Ketamine

• is classified as a dissociative agent
  • when administered at sedation/anaesthesia doses, the patient enters a dissociated state which is unlike other sedatives (1)
  • because ketamine works through an alternative pathway inducing dissociation rather than unconsciousness, the patient remains breathing on their own and able to protect their airway

Ketamine as an analgesic:

• has direct action primarily at the NMDA receptors in the central nervous system
• has activity at opioid sites and other neurotransmitter pathways (1)
  • can allow the out‐of‐hospital provider to augment analgesia in a safe and effective manner, reducing opioid requirements while decreasing suffering
  • in a study (n=251) intravenous ketamine showed non-inferiority for pain reduction compared to morphine (difference in mean pain score change 0.1 [95% CI −0.7 to 0.9]) (2)
    • a multicenter, single-blind, noninferiority randomized clinical trial comparing ketamine hydrochloride (20 mg, followed by 10 mg every 5 minutes) with morphine sulfate (2 or 3 mg every 5 minutes) in adult patients with out-of-hospital trauma and a verbal pain score equal to or greater than 5
    • among patients with out-of-hospital traumatic pain, the use of intravenous ketamine compared with morphine showed noninferiority for pain reduction in this randomized clinical trial
    • observed more adverse events in the ketamine group compared with the morphine group - these adverse events were minor and did not require intervention
• a cited concern regarding ketamine use in adults is that of the emergence reaction (1)
  • sometimes a patient waking up from ketamine dissociation can become agitated, confused and combative
  • emergence reactions in adults are rapidly managed with benzodiazepines

Reference:

1. Kitch BB. Out-of-hospital ketamine: review of a growing trend in patient care. J Am Coll Emerg Physicians Open. 2020 Mar 10;1(3):183-189
2. Le Cornec C et al. Ketamine Compared With Morphine for Out-of-Hospital Analgesia for Patients With Traumatic Pain. JAMA Netw Open 2024 Jan; 7(1): e2352844.