Cannabis use and anaesthetic agent dosing in patients undergoing surgery or interventional procedures: a...

There is limited evidence that habitual cannabis consumption increases anaesthetic requirements. We hypothesised that cannabis use affects anaesthetic dosing among patients undergoing surgery or interventional procedures.

A total of 341 199 adult patients undergoing propofol sedation or volatile-based general anaesthesia at Beth Israel Deaconess Medical Center, Boston, USA, between 2008 and 2024 were included. The primary exposure was cannabis use, differentiated into medical or non-medical use (recreational use or cannabis use disorder). Primary outcomes were propofol dose (μg kg^-1 min^-1) for monitored anaesthesia care and mean end tidal age-adjusted minimum alveolar concentration (MAC) values for general anaesthesia. In multivariable analyses, we estimated the adjusted difference in mean primary anaesthetic agent dosing.

A total of 23 896 patients (7.0%) were identified as non-medical cannabis users, and 3193 (0.9%) held a certification for medical cannabinoids. In adjusted analyses, both non-medical and medical cannabis use were associated with increased propofol doses (non-medical, +6.85 μg kg^-1 min^-1, 95% CI 6.07-7.63, P<0.001; medical, +2.87 μg kg^-1 min^-1, 95% CI 0.88-4.86, P=0.005) and doses of volatile anaesthetics (non-medical, +0.01 MAC, 95% CI 0.01-0.02, P<0.001; medical, +0.02 MAC, 95% CI 0.01-0.03, P=0.002). Estimated effects were strongest among frequent users (daily recreational users, +8.41 μg kg^-1 min^-1 propofol, 95% CI 7.00-9.81, P<0.001). At comparable propofol induction doses, non-medical cannabis users experienced greater heart rate increase after tracheal intubation (+1.45 beats min^-1, 95% CI 1.10-1.79, P<0.001).

Cannabis use was associated with modestly higher propofol and volatile anaesthetic doses. However, effect sizes were smaller than previously reported, and future studies should investigate the clinical relevance.