Safety and Effectiveness of Sedation With Adjunctive Ketamine Versus Nonketamine Sedation in the Medical Intensive Care Unit

Background: Ketamine, an N-methyl-d-aspartate receptor antagonist with sedative and analgesic properties, is becoming more popular as an adjunctive sedative in the critically ill patients. Methods: We conducted a single center, retrospective cohort study of patients admitted to the medical intensive care unit (MICU) between 2013 and 2018. Patients who received continuous infusion ketamine or nonketamine sedatives (NKS) including dexmedetomidine, fentanyl, midazolam, or propofol were identified. The primary outcome was percentage of Richmond Agitation-Sedation Scale (RASS) scores at goal in patients receiving ketamine as adjunct to NKS compared to those on NKS alone. Results: A total of 172 patients were included (n = 86 ketamine, n = 86 NKS). Baseline characteristics were similar with the exception of antipsychotic use, which was higher in the ketamine group ( P = .008). Percentage of RASS scores at goal was not different between groups (78.7% vs 81.4%, P = .29). Fewer patients in the ketamine group received continuous infusion fentanyl (76.7% vs 94.2%, P = .002). Patients on adjunctive ketamine required fewer days of intermittent benzodiazepines (0 [0-1] vs 1 [1-2], P < .0001). Patients receiving ketamine required less norepinephrine, receiving a median of 6.32 mg (2.4-20) versus 11.7 mg (5.2-45.2; P = .03). There was no difference in receipt of new antipsychotics or occurrence of arrhythmias. Conclusion: Addition of ketamine did not increase the percentage of RASS scores at goal versus NKS but was well tolerated. Ketamine was associated with reductions in norepinephrine requirements, days of intermittent benzodiazepine administration, and number of patients receiving continuous infusion fentanyl. Continuous infusion ketamine appears safe and effective for sedation in the MICU.