What question did this study set out to answer?

To determine the effect of high-dose ketamine on the incidence of delirium in ICU patients.

March 26, 2026

418: Effects of Ketamine Dosing on Delirium in Medical Icu Patients

Key Points

To determine the effect of high-dose ketamine on the incidence of delirium in ICU patients.
Retrospective cohort study design
Included mechanically intubated ICU patients receiving continuous ketamine
Exclusion of patients receiving ketamine for less than 24 hours or continuous paralytic therapy
Primary outcome measured by positive CAM-ICU score
Comparison of low-dose and high-dose ketamine groups
No significant difference in delirium incidence between low-dose (29.6%) and high-dose (31.6%) ketamine groups (p=0.89)
High-dose ketamine group had increased incidence of substance use or psychiatric disorders
Lower cumulative and daily ketamine doses in the low-dose group compared to the high-dose group (p<0.01)
No difference found in sedative, analgesic, or antipsychotic use between groups
No differences in hospital length of stay, ICU length of stay, or mortality

Abstract

Introduction: The 2018 PADIS guidelines recommend ketamine as an adjunct to reduce opioids but make no comment on its use for sedation. Ketamine has dissociative effects and literature on its effect on delirium is conflicting. The purpose of this study is to determine if high-dose ketamine increases incidence of delirium in intensive care unit (ICU) patients. Methods: A retrospective cohort study of mechanically intubated ICU patients receiving continuous ketamine for sedation between January 1, 2013 and June 30, 2025 was conducted. Patients who received ketamine for < 24h or received continuous paralytic therapy were excluded. The primary outcome was a positive CAM-ICU score while receiving or up to 72h after ketamine. Secondary outcomes included cumulative analgesic, sedative, and antipsychotic requirements, hospital length of stay (LOS), ICU LOS, and mortality. Patients were grouped into low-dose (< 1.2mg/kg/h) or high-dose (≥1.2mg/kg/h) based on the maximum rate. Results: Of the 46 patients included, 27 received low-dose ketamine (median dose 0.6mg/kg/h) and 19 received high-dose (median dose 2.5mg/kg/h). The low-dose group had a lower cumulative (186mg IQR: 814-6246 vs 8365mg IQR:5029-13180, p< 0.01) and daily dose (711mg/day IQR:429-1112 vs 2346 mg/day IQR:1549-3335, p< 0.01); however, there was no difference in duration (197h IQR:134-330 vs 50.1h IQR:37-122, p=0.80).The high-dose arm had an increased incidence of substance use and/or psychiatric disorders. There was no difference in the primary outcome, incidence of positive CAM-ICU scores between the low and high-dose arms (29.6% vs 31.6%, p=0.89). There was no difference in the receipt of the following agents while on ketamine in the low and high-dose arms: propofol (41% vs 68%, p=0.09), midazolam (74% vs 90%, p=0.67), dexmedetomidine (37% vs 37%, p=0.67), and fentanyl (89% vs 100%, p=0.14). No differences were seen in hospital LOS, ICU LOS, or mortality. Conclusions: Ketamine dosing did not have a significant effect on ICU delirium. There was no observed difference in sedative, analgesic, or antipsychotic use or patient outcomes between groups. Further research is needed to determine the effect of ketamine dosing on delirium.

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Cite This Study

Miller et al. (Sun,) studied this question.

synapsesocial.com/papers/69c4cc75fdc3bde448917b8b https://doi.org/https://doi.org/10.1097/01.ccm.0001183668.18191.81

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