Safety and Efficacy of the Prescribing Practices of Ketamine for Pain and Agitation in the Medical Intensive Care Unit.

BACKGROUND Ketamine has analgesic and sedative properties that are thought to reduce opioid tolerance and opioid-induced hyperalgesia. For this reason, ketamine may be used to manage pain and agitation, although the literature evaluating its use for this purpose is limited.

OBJECTIVE To describe the prescribing practices of ketamine in the medical intensive care unit (MICU) as it pertains to pain and agitation, as well as assess measures of safety and efficacy.

METHODS This was a single-center, retrospective cohort study of critically ill patients who received a ketamine infusion for pain and/or agitation between June 2021 and August 2024. The primary outcome was opioid consumption, reported in oral morphine milligram equivalents (MME), and sedative use pre- versus post-ketamine initiation. Secondary outcomes included paired mean pain scores, proportion of time within goal Richmond Agitation-Sedation Scale score range, and incidence of adverse events.

RESULTS For the 78 patients included, there was no difference in analgesic use pre- versus post-ketamine initiation (60 vs 45 MME; P = 0.677). No differences were observed in sedative doses required pre- versus post-ketamine initiation (5.3 vs 3.4 mg of benzodiazepines; P = 0.508, 0.9 vs 1.1 μg/kg/h of dexmedetomidine; P = 0.062, and 44 vs 44 μg/kg/min of propofol; P = 0.180). There was a median paired difference of -1 point on the pain scale ([interquartile range -1, 0]; P = 0.030) after ketamine initiation. Ketamine was associated with an increased incidence of hallucinations (1.3% vs 6.4%; P = 0.046).

CONCLUSION AND RELEVANCE To the authors' knowledge, this is the first study examining the use of ketamine for pain and/or agitation that specifically focuses on MICU patients. The clinical benefit of the routine use of ketamine for these indications in this patient population is unclear and may increase patients' risk of adverse effects such as hallucinations.