In this episode, I’ll discuss the effects of ketamine infusion rate and cumulative dosing on the incidence of delirium in medical intensive care unit patients.
Way back with the 2018 Pain, Agitation, Delirium, Immobility and Sleep Guidelines, ketamine was given the following positive recommendation for the use of ketamine saying:
We suggest using low-dose ketamine (0.5 mg/kg IVP x 1 followed by 1-2 μg/kg/min infusion) as an adjunct to opioid therapy when seeking to reduce opioid consumption in postsurgical adults admitted to the ICU.
At the time, the evidence for this recommendation was extremely thin. As I discussed back in episode 957, other expert critical care societies criticized this recommendation which at the time it was issued was based on a single study of 93 patients.
Ketamine use increased based on its presence in the guidelines, but evidence remained scant. To address this research issue, a group of authors recently published in the American Journal of Health-System Pharmacy a multicenter retrospective cohort study looking at the effects of ketamine infusion rate and cumulative dosing on incidence of delirium in medical intensive care unit patients.
The study included 114 mechanically ventilated adult medical ICU patients who received ketamine infusions for sedation. Just over a third of the cohort developed delirium. Patients with delirium had, on average, about 3 more days of mechanical ventilation, 4 more days of ICU length of stay, and received 60% higher cumulative morphine milligram equivalents.
No association was observed between delirium and the maximum hourly ketamine rate or cumulative dose of ketamine.
The authors concluded:
Maximum hourly ketamine infusion rate and cumulative dose in mechanical ventilated patients in the medical ICU were not associated with ICU delirium.
This study does provide some reassurance that it is unlikely ketamine has a dose-dependent effect on the incidence of ICU delirium. While ideally such information would predate a guideline recommendation, this study provides those guideline authors some post-hoc validation, at least from a safety standpoint.
The article in this episode is a selection from my Hospital Pharmacy Academy’s weekly literature digest. Have you ever felt like your physician colleagues are one step ahead of you with new literature developments? Every week, Academy members are provided a summary curated and explained by me of the top hospital pharmacy-related articles published that week from over 20 major journals and sources to save you time and keep you up to date with the literature. To get immediate access, go to pharmacyjoe.com/academy.
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