By Matthew Newton, DNP, CRNA
Cannabis use is increasingly prevalent, with legalization in many states making it more accessible to patients, leading anesthesia providers to encounter it more frequently in the perioperative period. This article aims to provide an update on cannabis use and its implications, along with recommendations for managing patients in the clinical setting. Anesthesia providers need to approach discussions about cannabis use in a welcoming, non-judgmental manner to encourage transparency while acknowledging that societal stigma has not been fully eliminated.
Studies indicate that up to 14-20% of surgical patients report cannabis use, a figure expected to rise as legalization expands. Cannabis use should be treated similarly to alcohol use during preoperative evaluations, as it may influence a patient’s ability to consent due to cognitive impairment. Tetrahydrocannabinol (THC), the primary psychoactive compound, and cannabidiol (CBD) interact with the endocannabinoid system through CB1 and CB2 receptors, impacting various physiological processes.
Cannabis induces several physiological changes relevant to anesthesia, including tachycardia, hypotension, and altered pain thresholds. THC’s metabolism via the CYP450 enzyme system, particularly CYP2C9 and CYP3A4, can inhibit or compete with other drugs, affecting their metabolism. Delivery methods significantly influence THC’s onset and duration; inhalation results in rapid effects typically lasting 1-3 hours, while edibles can exhibit a delayed onset with prolonged effects, complicating perioperative management. Since there is such a variety of administration routes of THC with unique onsets and durations, it is difficult for the provider to properly judge if the patient can appropriately consent. It’s recommended there is no THC consumption on the day of the procedure. The anesthesia provider should use their best clinical judgment on how to proceed. If there are any questions, they should collaborate with their onsite physician or reach out to their medical director.
CBD oil, often perceived as benign, also interacts with the CYP450 system and binds predominantly to CB2 receptors, influencing inflammation and immune response. Although less psychoactive than THC, its effects on sedation and drug interactions warrant consideration. Cannabis use has systemic effects that influence anesthesia, including airway hyperreactivity, increased risk of laryngospasm, and concerns about vocal cord edema. These risks necessitate heightened vigilance during the administration of anesthesia and airway management.
Paradoxically, while cannabis has antiemetic properties, sudden dosage changes or discontinuation can precipitate cannabinoid hyperemesis syndrome (CHS), characterized by severe nausea and vomiting. CHS presents unique challenges in the perioperative setting and may require tailored antiemetic strategies.
Perioperative cannabis use and THC consumption pose multifaceted challenges for anesthesia providers. A thorough patient history, including cannabis and CBD use, is critical. Approaching the patient’s assessment with a non-judgmental and comforting attitude may contribute to receiving a complete and honest conversation with the patient regarding drug use. Understanding cannabis’s pharmacodynamics, delivery methods, and systemic effects can guide anesthetic planning and improve patient safety. Providers should remain informed about emerging research as cannabis becomes more prevalent in clinical practice.
References
- National Institute on Drug Abuse. Monitoring the Future Study: Trends in Prevalence of Various Drugs. Updated December 2023. https://www.drugabuse.gov
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- Shah S, Schwenk ES, Sondekoppam RV, et al. ASRA Pain Medicine consensus guidelines on the management of the perioperative patient on cannabis and cannabinoids. Reg Anesth Pain Med. 2023;48(1):5-26. doi:10.1136/rapm-2022-103682
- Soriano T, Scott BK. Perioperative Considerations for Cannabis Users. Curr Opin Anaesthesiol. 2020;33(3):411-417. doi:10.1097/ACO.0000000000000864.
- Monte AA, Shelton SK, Mills E, et al. Acute Illness Associated with Cannabis Use, by Route of Exposure: An Observational Study. Ann Intern Med. 2019;170(8):531-537. doi:10.7326/M18-2809.
