Cannabis use is associated with higher intravenous anesthetic administration. Similar data regarding inhalational anesthetics are limited. With rising cannabis use prevalence, understanding any potential relationship with inhalational anesthetic dosing is crucial. Average intraoperative isoflurane or sevoflurane minimum alveolar concentration equivalents between older adults with and without cannabis use were compared.
The electronic health records of 22,476 surgical patients 65 yr or older at the University of Florida Health System between 2018 and 2020 were reviewed. The primary exposure was cannabis use within 60 days of surgery, determined via (1) a previously published natural language processing algorithm applied to unstructured notes and (2) structured data, including International Classification of Diseases codes for cannabis use disorders and poisoning by cannabis, laboratory cannabinoids screening results, and RxNorm codes. The primary outcome was the intraoperative time-weighted average of isoflurane or sevoflurane minimum alveolar concentration equivalents at 1-min resolution. No a priori minimally clinically important difference was established. Patients demonstrating cannabis use were matched 4:1 to non–cannabis use controls using a propensity score.
Among 5,118 meeting inclusion criteria, 1,340 patients (268 cannabis users and 1,072 nonusers) remained after propensity score matching. The median and interquartile range age was 69 (67 to 73) yr; 872 (65.0%) were male, and 1,143 (85.3%) were non-Hispanic White. The median (interquartile range) anesthesia duration was 175 (118 to 268) min. After matching, all baseline characteristics were well-balanced by exposure. Cannabis users had statistically significantly higher average minimum alveolar concentrations than nonusers (mean ± SD, 0.58 ± 0.23 vs. 0.54 ± 0.22, respectively; mean difference, 0.04; 95% confidence limits, 0.01 to 0.06; P = 0.020).
Cannabis use was associated with administering statistically significantly higher inhalational anesthetic minimum alveolar concentration equivalents in older adults, but the clinical significance of this difference is unclear. These data do not support the hypothesis that cannabis users require clinically meaningfully higher inhalational anesthetics doses.
- Cannabis use is associated with higher intravenous anesthetic administration for general anesthesia
- Similar data regarding cannabis users and inhaled volatile anesthetic administration are limited by challenges in accurately identifying cannabis users using structured electronic health record data and small sample size
- Using a combination of natural language processing of free text notes and structured electronic health record documentation, 268 older adults (age 65 yr or older) with documentation of cannabis use within 60 days before surgery were compared to 1,072 similar older adults without documentation of cannabis use
- Cannabis users received a time-weighted average volatile minimum alveolar concentration of 0.58 (SD, 0.23) compared to 0.54 (SD, 0.22)
- Although this mean difference of 0.04 minimum alveolar concentration was statistically significant, the clinical significance of this difference is unclear and does not support the hypothesis that older adult cannabis users require clinically meaningful higher inhalational anesthetic dosing
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