Cannabis Use and Inhalational Anesthesia Administration in Older Adults: A Propensity-matched Retrospective Cohort...

Area of Science:

• Anesthesiology
• Pharmacology
• Geriatric Medicine

Background:

• Cannabis use is rising, yet its impact on inhalational anesthetic requirements is not well-understood.
• Previous studies linked cannabis to higher intravenous anesthetic doses, but data on inhalational agents are limited.
• Understanding this relationship is crucial for optimizing anesthesia in older adults.

Purpose of the Study:

• To compare the average intraoperative minimum alveolar concentration (MAC) equivalents of isoflurane or sevoflurane in older adults with and without cannabis use.
• To investigate the potential association between cannabis consumption and inhalational anesthetic dosing in surgical patients.

Main Methods:

• Retrospective review of 22,476 surgical patients aged 65+ at a major health system (2018-2020).
• Cannabis use identified via NLP, ICD codes, lab results, and RxNorm; defined as use within 60 days of surgery.
• Propensity score matching (4:1) used to compare 268 cannabis users with 1,072 nonusers based on baseline characteristics.

Main Results:

• After matching, cannabis users received statistically significantly higher average minimum alveolar concentration (MAC) equivalents (0.58 ± 0.23) compared to nonusers (0.54 ± 0.22).
• The mean difference in MAC was 0.04 (95% CI: 0.01 to 0.06; P = 0.020).
• While statistically significant, the clinical importance of this difference in anesthetic dosing is uncertain.

Conclusions:

• Cannabis use in older adults was associated with higher administered inhalational anesthetic MAC equivalents.
• The clinical significance of this observed difference in anesthetic requirements is currently unclear.
• The study does not support the hypothesis that cannabis users necessitate clinically meaningful increases in inhalational anesthetic doses.