Perioperative medicine & outcomes
Dose‐dependent relationship between intra‐operative ketamine administration and postoperative delirium: a retrospective cohort study
Authors' conclusion
Intra-operative low-dose ketamine was associated with a lower risk of postoperative delirium, while high doses did not influence the risk.
Study context
- Population
- Adults undergoing GA for non-cardiac, non-neurosurgical and non-transplant procedures, 2008–202412,199 (11.4%) received ketamine
- Participants
- 106,982 adults
- Exposure
- Intra-operative low-dose or high-dose ketamine vs no ketamine
- Low dosen = 6,109
- Higher dosesn = 6,090
- Outcome
- Postoperative delirium
- Follow-up
- Within 7 days
Methodological detailsmultivariable logistic regression, fractional polynomial regression
- Multivariable logistic regression
- Fractional polynomial regression
Main finding
As reported in the abstract
Postoperative delirium within 7 days
Each group vs no ketamineAdjusted odds ratio (95% CI)P value
Low doseadjusted risk difference −0.7% (95%CI −1.0 to −0.3%)
0.74(0.59–0.89)
P = 0.003Higher doses
1.00(0.85–1.18)
P = 0.96- Postoperative delirium, whole cohort
- 2837 (2.7%)
Observational data: associations, not effects.
Further findings
Dose-response relationship (fractional polynomial regression)
- U-shaped dose-response; minimum postoperative delirium risk at cumulative ketamine dose
- 0.25-0.34 mg.kg-1
Intra-operative ketamine dose among recipients
- Median (IQR [range]) dose, mg.kg-1
- 0.35 (0.25-0.52 [0.01-3.86])
Original publication
Dose‐dependent relationship between intra‐operative ketamine administration and postoperative delirium: a retrospective cohort study. Anaesthesia. Published 6 July 2025. doi:10.
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