EBQ:Subdissociative ketamine vs morphine for analgesia

Complete Journal Club Article
Motov S, Rockoff B, et al.. "Intravenous Subdissociative-Dose Ketamine Versus Morphine for Analgesia in the Emergency Department: A Randomized Controlled Trial". Ann Emerg Med. 2015. 66(3):222-229.
PubMed Full text PDF

Clinical Question

Is subdissociative-dose ketamine comparable in terms of analgesia to morphine when administered in the emergency department?


Subdissociative intravenous ketamine provides analgesic effectiveness and may be as safe as morphine in the emergency department, but does cause patients to complain of disorientation, dizziness, and mood changes.

Major Points

Ketamine, a dissociative analgesic can be used for both acute pain relief and procedural sedation. At lower doses (0.1-0.3mg/kg) produces only analgesic effects with minimal to no dissociation[1][2] Studies have also shown that ketamine has significant analgesic properties at sub-dissociative doses.[3] The authors of this study, compared in a randomized fashion, the analgesic properties of subdissociative ketamine to morphine, for acute pain control. Pain relief between the ketamine and morphine groups were statistically similar but is associated with greater patient complaints than IV morphine.

Study Design

  • Randomized controlled supiority trial at a single emergency department (Maimonides Medical Center NY, USA


Patient Demographics

  • Age: 18yo - 55yo
  • Female: 29%
  • Weight: 76kg
  • Systolic BP: 126kg
  • Baseline Pain score: 8.6 out of 10 ketamine group, 8.6 out of 10 morphine group


  • Patients with pain of the abdomen, back, flank or musculoskeletal system that of at least a 5 out of 10 (on a scale from 0 to 10) and necessitating narcotic analgesia per the attending physician.


  • Pregnancy,
  • Breast-feeding
  • Altered mental status
  • Allergy to morphine or ketamine
  • Weight less than 46 kg or greater than 115 kg
  • Unstable vital signs defined as:
    • Systolic blood pressure <90 or >180 mm Hg
    • Pulse rate <50 or >150 beats/min
    • Respiration rate <10 or >30 breaths/min
  • Medical history of:
    • Acute head or eye injury
    • Seizure, intracranial hypertension
    • Chronic pain
    • Renal or hepatic insufficiency,
    • Alcohol or drug abuse
    • Psychiatric illness
    • Recent (4 hours before) opioid use


  • 0.3mg/kg Ketamine or 0.1mg/kg of morphine IV


Primary Outcome

30 min numeric pain rating for ketamine vs morphine

  • Ketamine: 4.1 (SD ±3.2)
  • Morphine: 3.9 (SD ±3.1)

Secondary Outcomes

Pain scores (Ketamine vs Morphine on scale of 1-10)

  • 15 min: 3.2 v 4.2
  • 30 min: 3.2 vs 4.2
  • 60 min 4.8 v 3.4
  • 90 min: 4.8 v 3.9
  • 120 min: 3.9 vs 3.7

Adverse Effects

Ketamine v Morphine

  • Dizziness:
    • 15 min: 53% v 31%
    • 30 min: 8% v 6%
  • Disorientation:
    • 15 min: 11% v 0%
    • 30 min: 1% v 0%
  • Mood Changes:
  • 15 min: 11% v 0%
  • 30 min: 1% v 0%
  • Nausea
  • 15 min: 18% v 11%
  • 30 min: 6% v 9%

Criticisms & Further Discussion

  • This study describes the use of ketamine in the emergency department and provides preliminary data for a multi-centered study.
  • Ketamine may over similar analgesia at 30 min but does cause greater frequency of dizziness, mood changes and disorientation when compared to morphine. Although these side effects are not life threatening, proper explanation of ketamine should be given to the patient prior to administration due to the greater frequency when compared to morphine.
  • There are significant exclusions for this study, as in any randomized trial and abstraction of the study to excluded patients is not possible

External Links

See Also


  • Funded in part by a grant from the New York Department of Health’s Empire Clinical Research Investigator Program


  1. Galinski MM, Dolveck FM, Combes XM, et al. Management of severe acute pain in emergency settings: ketamine reduces morphine consumption. Am J Emerg Med. 2007;25:385-390.
  2. Smith D, Mader T, Smithline H. Low dose intravenous ketamine as an analgesic: a pilot study using an experimental model of acute pain. Am J Emerg Med. 2001;19:531-532
  3. Jennings PP, Cameron PM, Bernard SM, et al. Morphine and ketamine is superior to morphine alone for out-of-hospital trauma analgesia: a randomized controlled trial. Ann Emerg Med. 2012;59:497-503.