Surgery and Cannabis: Should You Screen All Patients Before Surgery?
By Eric Zacharias, MD
Over the last two decades, there has been a significant increase in the number of Americans who regularly use cannabis with approximately 10% of the population reporting monthly or greater use. Additionally, cannabis use disorder—clinically significant impairment caused by the recurrent use of marijuana—is believed to be present in about 6 percent of surgical patients.1,2
Due to the potential for cannabis to impact physiology in multiple domains and for these impacts to adversely affect patients in the perioperative period, the American Society of Regional Anesthesia and Pain Medicine has recently updated its consensus guidelines on management of the perioperative patient on cannabis and cannabinoids.3 These guidelines are not intended to supersede clinical judgment but are designed to enhance person-centered decision making in the clinical realm.
Key points include:
Prior to any surgery requiring anesthesia, the anesthesiologist should ask the patients if they use cannabis, including frequency, method of use, and when last used.
Anesthesiologists and surgeons should be prepared for the possibility that they may need to alter the perioperative anesthesia plan and/or delay the operation based on when cannabis was last used.
Procedures should be delayed for at least two hours from recent smoking of cannabis to avoid increased risk of myocardial infarction. This delay may need to be longer for other routes of administration based on clinical judgment.
Elective procedures should be postponed if a patient is impaired with altered mental status from acute cannabis intoxication.
Although the myriad potential clinical impacts of cannabis in the surgical patient are beyond the scope of this overview, there are several important effects to consider. A key point is to maintain vigilance to the possibility that any cannabis and CBD products used by a patient may contain contaminants that could also impact their physiology. Additional considerations include:
Cardiovascular effects from cannabis include an increased risk of perioperative myocardial infarction with recent usage as well as tachycardia from reduced parasympathetic activity and peripheral vasodilation.
Anesthesia requirements may be impacted as well as the need for postoperative opioids.
The respiratory system effects can include respiratory depression as well as bronchospasm from smoking or vaping, and difficulty with airway management.
The gastrointestinal effects include increased postoperative nausea and vomiting.
Lastly, cannabis and cannabinoids can impact anticoagulants and antiplatelets as well as the major enzyme systems involved in the metabolism of multiple classes and types of medications.
In summary, cannabis and cannabinoids usage is common, and this may continue to increase in all regions of the country as state and federal laws become more permissive. These substances can have implications in multiple realms of care for the perioperative patient, and current guidelines advise screening all patients for cannabis use prior to surgery and using that information along with medical judgment to help optimize patient safety in a given surgical scenario.
Eric Zacharias, MD, is part of the COPIC Department of Patient Safety and Risk Management.
1 Substance Abuse and Mental Health Services Administration. (2018). Key substance use and mental health indicators in the United States: Results from the 2017 National Survey on Drug Use and Health (HHS Publication No. SMA 18-5068, NSDUH Series H-53). Rockville, MD: Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration.
2 McAfee J, Boehnke KF, Moser SM, et al. Perioperative cannabis use: a longitudinal study of associated clinical characteristics and surgical outcomes. Reg Anesth Pain Med 2021; 46:137.
3 Shah S, et al. ASRA Pain Medicine consensus guidelines on the management of the perioperative patient on cannabis and cannabinoids. Reg Anesth Pain Med. 2023 Mar;48(3):97-117. Epub 2023 Jan 3.