Is There a Role for Intravenous Sub-Dissociative-Dose Ketamine Administered as an Adjunct to Opioids or as a Single Agent for Acute Pain Management in the ED?
AAEM Clinical Policy Review (AAEM, 9/2015)
The authors of this clinical policy sought to define a literature basis for the relatively recent popularity of “low-dose” ketamine for acute parenteral analgesia in the Emergency Department, either alone or in conjunction with intravenous opioids.
They did this by reviewing eight articles from both the pre-hospital and ED arenas. The articles ranged in strength, from prospective, observational studies to several randomized, double-blinded, placebo-controlled trials, to systematic reviews. In all articles, ketamine either showed a benefit or at least appeared non-inferior to standard therapies, such as hydromorphone or morphine. Specifically, using ketamine with intravenous opioids reduced the required dose for the latter in most cases. Time to effective analgesia was usually shorter. When compared head-to-head, ketamine had a faster onset but required more frequent re-dosing. There were consistent and not unusual reports of previously published adverse effects when ketamine was used, including nausea, dizziness, “and feelings of unreality.”
Emergency physicians face pain management challenges perhaps more than any of our colleagues in other specialties; in many ways pain is the essence of the emergent complaint. It follows, then, that if we are to be experts in delivering emergency care, we should provide exemplary pain control at the same time. We should not be one-trick ponies (read: opiate dispensers) but rather have a variety of analgesic plans that we can tailor to our individual patients.
Ketamine is a legitimate addition to the classic opioid pain cocktails, especially in a patient milieu increasingly plagued by narcotic abuse and dependency. It is fast-acting, lacks significant hemodynamic or respiratory adverse effects, and can be dosed easily.
For my clinical practice, this has become an adjunct but certainly has not replaced opioids. It seems most appropriate for patients with difficult-to-control pain or those in whom we would like to avoid narcotics. Given the fairly common set of side-effects, I would not use this instead of the more benign first-line parenteral therapy: fentanyl or ketorolac. Much of the data cited in this guideline points to its benefits when added to narcotics. It has the obvious weakness of no easily employed oral alternative and it cannot be prescribed. Like most therapies, I have found this one to be most effective when the patient is adequately educated about the potential adverse effects of the medication before they receive it.
Low-dose ketamine (0.1-0.4 mg/kg, IVP) is a nice adjunct or alternative to heavier narcotic doses and should be considered in patients with moderate to severe pain. These patients can be placed on low-dose infusions once admitted, as well. If you are not making sufficient headway with Dilaudid, add ketamine.
Ketamine in this dose range can now be administered by the ED nursing staff at the bedside.
Educate the patient and the nurses prior to using ketamine to maximize success.
Know the side-effects and be prepared to react.
Written by Sheldon Stevenson, MD
Edited and Posted by Jeffrey A. Holmes, MD