Clinical Pharmacy Specialist UPMC Saint Margaret Pittsburgh, Pennsylvania
Introduction: Low dose ketamine is currently guideline-recommended as an adjunct to opioids in postsurgical patients in the intensive care unit (ICU) to decrease opioid use. Current guidelines do not address ketamine continuous infusions for sedation. At the study institution, ketamine continuous infusions are used for both light and deep sedation as determined by the patient’s Riker Sedation-Agitation Scale (Riker-SAS) score. The objective of this study was to characterize the use of ketamine continuous infusions when used for light and deep sedation in a medical-surgical ICU.
Methods: This is a single-center retrospective study evaluating ketamine usage. Adult patients admitted to the ICU who received a ketamine continuous infusion for sedation from October 2018 to January 2021 were included. The primary outcome was to determine the minimum and maximum doses of ketamine for light (RIKER-SAS 3-4) versus deep sedation (RIKER-SAS 1-2). Additional outcomes included time to achievement of the ketamine titration goal, number of concomitant sedatives used, and presence of hemodynamic instability.
Results: Seventeen patients with thirty ketamine continuous infusion orders were included in the analysis. Eighteen orders were titrated to light sedation and twelve orders were titrated to deep sedation. The median minimum and maximum infusion rates were 0.2 mg/kg/hr and 0.72 mg/kg/hr for light sedation compared to 0.27 mg/kg/hr and 1 mg/kg/hr for deep sedation, respectively. For orders when the titration endpoint was met, the median time to ordered Riker-SAS score was 124 minutes for light sedation and 796 minutes for deep sedation. An average of two concomitant sedatives were used in both groups. When used for light sedation, ten orders were given in combination with vasopressors and four were given with anti-hypertensives. When used for deep sedation, eight orders were given with vasopressors and two were given in combination with anti-hypertensives.
Conclusions: The median maximum infusion rate of ketamine was higher for orders targeting deep sedation, likely providing more of a dissociative effect. However, orders that were for deep sedation took a longer time to meet the titration goal. Based on these results, additional or alternative agents may be required to achieve deep sedation more effectively.
