Cannabis Use and Anesthetic Requirements During Deep Sedation for Third Molar Removal: A Retrospective Cohort Study

Background As cannabis legalization expands, dental and oral and maxillofacial surgery providers increasingly encounter patients with recent or chronic cannabis use. Cannabis affects the central nervous and cardiopulmonary systems and may alter patient responses to intravenous (IV) sedative agents. Methods A retrospective cohort study was conducted at the University of Michigan School of Dentistry, including patients aged ≥16 years who underwent deep sedation for mandibular third molar extraction between June 2022 and December 2024. Patients were stratified by self-reported cannabis use. Primary outcomes were weight-adjusted dosages of propofol, ketamine, fentanyl, and midazolam; secondary outcomes were intraoperative complications, including oxygen desaturation and inadequate ventilation. Multivariable linear regression evaluated the association between cannabis use and weight-adjusted dose for each medication separately, adjusting for the number of inadequate ventilation instances, desaturation occurrence, and sedation time. Group comparisons used t-tests or Mann-Whitney U tests for continuous variables and chi-square or Fisher’s exact tests for categorical variables; significance was set at P < 0.05. Results Of 589 patients, 175 (29.7%) reported cannabis use. In unadjusted comparisons, cannabis users had significantly higher weight-adjusted doses of propofol, ketamine, and midazolam than non-users (all P<0.05); fentanyl dose did not differ significantly (P=0.38). After adjustment, cannabis use remained independently associated with higher weight-adjusted propofol (β=0.74; 95% CI, 0.47 to 1.0; P<0.001) and ketamine (β=0.07; 95% CI, 0.03 to 0.12; P<0.001) dosing, but was not independently associated with fentanyl (β=0.02; 95% CI, -0.07 to 0.10; P=0.736) or midazolam (β=0.00; 95% CI, 0.00 to 0.01; P=0.080) dosing. Cannabis users had significantly more instances of inadequate ventilation than non-users (mean 3.0 vs 2.5; P=0.002); rates of desaturation, airway adjunct use, bag-mask ventilation, and other adverse events did not differ significantly between groups. No significant differences were found between groups in age, sex, or BMI. Conclusion Cannabis use was independently associated with higher weight-adjusted propofol and ketamine requirements and with more frequent inadequate ventilation during deep sedation; the association with midazolam dosing did not persist after adjustment, and fentanyl dosing was unaffected. Given the retrospective, observational design, these findings support an association rather than a causal relationship. They suggest cannabis use may be a relevant factor in preoperative sedation planning, though prospective studies with objective exposure confirmation are needed before specific practice changes can be recommended.