Etomidate Dosing and Recovery in Cannabis Users in Wada Test

Introduction: The Wada test involves the intracarotid injection of anesthetics—commonly etomidate—to transiently anesthetize one hemisphere for assessing language and memory dominance during presurgical evaluation. However, evidence on guiding intracarotid etomidate remains limited. This retrospective study aimed to investigate cannabis use and other factors such as body weight that may influence the intracarotid etomidate dosing regimen. Methods: We included all adults who underwent the Wada test at our institution between February 2012 and January 2024. The primary exposure was cannabis use. The primary outcome was the total etomidate dose, defined as the cumulative amount (mg) required to achieve and maintain hemispheric anesthesia during each injection. Multivariable linear regression analysis was performed to assess the association between active cannabis use and total etomidate dose. We also compared the pharmacodynamic characteristics between cannabis users and nonusers. Results: A total of 47 patients with 98 intracarotid etomidate injections were included. Active cannabis use was significantly associated with an increased total etomidate dose per injection (adjusted β=0.99, 95% CI: 0.03-1.9, P =0.04). Factors such as age, sex, body weight, and a history of alcoholism or other drug abuse were not significantly associated with the dose. Cannabis users experienced faster recovery, with a shorter time from the initial bolus to motor strength recovery (624 s [441 to 808] vs. 750 s [564 to 908], P =0.01). Discussion: Our findings suggest that cannabis use is associated with a higher dose requirement of intracarotid etomidate and faster recovery times following cessation of the etomidate infusion.