COMMENTARY

Ketamine: Another Option for Managing Acute Pain?

Sumit Patel, MD

Disclosures

July 19, 2017

Ketamine as an Adjunct to Opioids for Acute Pain in the Emergency Department: A Randomized Controlled Trial

Bowers KJ, McAllister KB, Ray M, Heitz C
Acad Emerg Med. 2017;24:676-685

Study Summary

In this randomized, double-blinded, placebo-controlled trial, researchers enrolled a study population of 116 people to determine the efficacy of ketamine for pain control when used in conjunction with opioids. Patients were included in the study if they were between 18 and 70 years of age, had pain greater than 6 out of 10 on the numerical rating scale (NRS-11), and had intravenous (IV) opioid analgesics ordered by their treating emergency medicine physician prior to study enrollment.

Exclusion criteria were numerous, including: sensitivity to the study drugs; active psychosis; clinical intoxication; presentation with headache or chest pain; pregnancy; concern by treating physician or study personnel of current or prior history of narcotic abuse or secondary gain; cirrhosis; hepatitis; chronic ventilation dialysis; systolic blood pressure < 90 mm Hg; systolic/diastolic blood pressure > 160/90 mm Hg; Glasgow Coma Score < 15; or signs of respiratory distress.

Patients were enrolled by research personnel in a single large tertiary care referral center emergency department (ED) with an annual census of 90,000 visits during evenly distributed shifts across days, nights, and weekends. Of the 116 individuals who were enrolled in the study, 63 were randomly assigned to receive placebo and opioids, and 53 were randomly assigned to receive ketamine and opioids.

Study participants received their initial dose of IV opioid analgesic as determined by their treating physician. Their pain was reevaluated 15 minutes after this initial dose. If the patient still had pain equal to or greater than 6 out of 10 on the NRS-11 scale, they provided signed informed consent and were randomly assigned to the study or control group. The study group received 0.1 mg/kg of ketamine over 1 minute. The control group received 0.1 mg/kg of normal saline. All ED bedside treatment personnel and the patients were blinded to the contents of each otherwise identical syringe. Patients were reevaluated at 30-minute intervals, and if they needed additional pain control they were given 0.05 mg/kg doses of IV morphine or equivalent opioid dosing. Vital signs, level of sedation (Ramsay score), pain levels, satisfaction levels (Likert scale), side effects, and all doses of medication were recorded. Patients were monitored for a total period of 120 minutes. Treating physicians were able to give both opioid and nonopioid analgesics at their discretion throughout the 120-minute treatment period if they felt it was necessary for patient care. If patients requested analgesia prior to the next 30-minute check point, their physician was permitted to administer analgesia to ensure that patients did not undergo any unnecessary lack of analgesia for study purposes.

The two primary outcomes that researchers used were level of pain control and satisfaction of pain control. Patients in the ketamine group had statistically significant lower pain scores than those in the control group. The level of pain satisfaction was not significantly different between the two groups. The total amount of opioid analgesia administered in the ketamine group was lower than in the control group and was statistically significant. More patients had side effects such as lightheadedness and dizziness in the ketamine group.

Viewpoint

As the opioid epidemic continues to become an increasingly frightening and important issue for us, nonopioid analgesic options are increasingly relevant. Although ketamine has been used primarily in the field of anesthesia, emergency physicians do routinely use it for patients who require rapid sequence intubation, delayed sequence intubation, and conscious sedation, or for agitated delirium or other acute conditions. Currently, practice patterns vary on the basis of department location, hospital policy, and a multitude of other factors. Although this study did not show a significant difference in patient satisfaction levels, satisfaction levels were not lower in the ketamine group, and patients overall had markers of better analgesia over the course of the study.

Although patients in the ketamine group also had more side effects, the use of ketamine as an adjunct certainly appears to be a safe option in certain patients. More research is needed with larger numbers of study participants, but it is safe to bet that in the near future, emergency physicians will probably be able to add ketamine to their toolbox of options for managing acute pain.

Abstract

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