P049: CANNABIS USE AND PERIOPERATIVE ANESTHETIC MANAGEMENT: CLINICAL IMPLICATIONS AND EVIDENCE GAPS
Trevor Virno1; Carl Van Rensburg1; Anne Carney1; Mary Carney, MD2
1LECOM-Bradenton; 2Cooper University Hospital Department of Anesthesiology
Introduction/Background: Cannabis use is increasingly prevalent among surgical patients, especially in states with legalized medical and recreational cannabis. Despite its growing use, there are still perioperative implications that remain incompletely characterized. Emerging data suggest clinical effects of anesthetic dosing, postoperative pain, and cardiovascular risk. This analysis synthesizes current clinical and pharmacokinetic evidence to clarify findings and identify gaps relevant to anesthesiology.
Methods: A structured review of the literature was conducted. Systematic reviews, meta-analyses, large retrospective cohort studies, pharmacologic studies, and consensus-based perioperative guidelines were examined and critically assessed. Outcomes of interest included anesthetic medication requirements, postoperative pain and opioid use, cardiovascular events, pulmonary complications, and postoperative nausea and vomiting (PONV). Evidence was examined for consistency across study designs and biologic plausibility.
Results: Chronic cannabis use is consistently associated with increased anesthetic medication requirements, particularly gamma-aminobutyric acid (GABA)–ergic hypnotics. A recent meta-analysis demonstrated that cannabis users required approximately 47 mg more propofol compared with non-users, independent of procedural duration. Procedure-specific cohort studies reported a similar increase in requirements for propofol, midazolam, fentanyl, and ketamine after adjustment for age and ASA classification.
Mechanistic studies show a possible pharmacokinetic origin to cannabis use and altered anesthetic outcomes. Chronic tetrahydrocannabinol (THC) exposure is associated with CB1 receptor downregulation, affecting GABA and glutamate signaling, reducing sensitivity to hypnotics and resulting in a functional tolerance of sedatives. Cannabidiol (CBD) inhibits multiple cytochrome P450 enzymes (including CYP3A4, CYP2C19, CYP2D6, and CYP2C9) while THC may induce certain cytochrome P450 enzymes (specifically CYP1a2) creating a bidirectional unpredictability in drug metabolism.
While cannabis is used as an analgesic for a variety of chronic pain states, perioperative cannabis users demonstrate higher postoperative pain scores and greater opioid consumption compared with non-users. This “pain paradox” associated with cannabis use could be linked to central sensitization, altered opioid receptor signaling, or cannabinoid induced hyperalgesia.
The older consensus that cannabis smokers mirrored tobacco smokers seems to only be partially supported. Pulmonary complications appear less consistently increased, though airway hyperreactivity has been described. Cardiovascular effects do appear clinically significant with acute exposure associated with tachycardia, hemodynamic variability, and increased odds of postoperative myocardial infarction seen among patients with cannabis use disorder. Cannabis exposure has also been associated with a modest increase in PONV risk.
Discusion/Conclusion: Current evidence supports cannabis use as a clinically relevant modifier of clinical anesthetic procedure and perioperative risk. Chronic use is associated with increased anesthetic medication requirements, altered postoperative pain responses, and cardiovascular vulnerability, while cannabinoid-related enzyme alteration may increase interpatient variability. Routine preoperative screening should assess pattern and severity of use rather than simple exposure. Anticipatory dose planning, multimodal analgesia strategies, and cardiovascular vigilance may improve perioperative management. Prospective studies incorporating objective exposure measurement, route- and timing-specific analyses, and controlled anesthetic dosing trials are needed to better define dose–response relationships and guide evidence-based practice.