Finally detailed and informed advice on the potential interactions between cannabis and anesthetic medications before, during, and after surgery is taking shape.
The first guidelines on cannabis use and the surgery timeline were published on Jan. 3 by the American Society of Regional Anesthesia and Pain Medicine (ASRA Pain Medicine), who acknowledged that up until now there is “no single document” that summarizes all of these concerns.
The guidance is based on known data and recommendations from the Perioperative Use of Cannabis and Cannabinoids Guidelines Committee—a group composed of 13 anesthesiologists, chronic pain physicians, experts, and patient advocates.
The committee answered nine questions and made 21 recommendations using a modified Delphi consensus method. They arrived at an over 75% agreement required for recommendation, and all 21 recommendations achieved full consensus.
Recommendations include screening all patients before surgery; postponing elective surgery in patients who have altered mental status or impaired decision-making capacity at the time of surgery; Counseling frequent users on the potentially negative effects of cannabis use on postoperative pain control; Counseling pregnant patients on the potential risks of cannabis use to the unborn child.
Addressing Surgery and Cannabis Concerns
“While many of the perioperative risks and challenges related to perioperative cannabis, such as how to advise patients preoperatively, the effects of cannabis on anesthetic medications, and the interaction between cannabis, opioids, and pain, have been described in the literature, there is no single document that summarizes all of these concerns and provides evidence-based recommendations,” the document reads.
The document continues, “Flexibility in this clinical practice guideline is intended to enable person-centered decision-making that takes into account an individual’s expected health outcomes and well-being within the context of various regulatory environments.”
No recommendations were made for the reduction of cannabis administered by other non-smoking routes before surgery “due to current lack of evidence;” the routine tapering of cannabis and cannabinoids before, during, or after surgery; the use of intraoperative electroencephalogram (EEG) in patients who have taken cannabinoids; nor adjusting opioid prescriptions afterward in surgical patients who use cannabinoids.
Authors noted the wide range of recommendations for pre-op patients, but cautioned that surgery should be postponed for a minimum of two hours after smoking cannabis. People who rely on medical cannabis are advised to taper off before surgery in some cases.
Most current recommendations, however, advise patients to abstain from cannabis a few to 10 days prior to surgery. “A recent consensus-based guideline recommended reducing cannabinoid use 7 days prior to surgery (to less than 1.5 g/day of smoked cannabis, 300 mg/day of CBD oil, 20 mg/day of THC oil) while cautioning not to attempt any tapering strategies within 6 days of elective surgery and not to attempt tapering a day prior to surgery.”
The document continues with the range of guidance, “Contrary to this recommendation, recent reviews of perioperative cannabinoids recommended cessation 72 hours prior to surgery. An even more conservative recommendation was recently provided, in which the authors recommended up to 10 days of cessation of oral cannabis consumption.”
Does Cannabis Impact An Anesthesia?
Research has a long way to go, however there is a growing body of evidence showing potential interactions and effects of cannabis before or after surgery.
One study published in Baylor University Medical Proceedings in 2019 shows that cannabis consumers may require higher doses of anesthesia than non-consumers, as well as a slew of other potential interactions, while another study found no significant difference before surgery in the gastrointestinal tract.
Cannabis might be an issue at the dentist as well. There is a strong belief that cannabis interacts with novocaine and local anesthetics like lidocaine. In one study dating back to 1976, THC interacted undesirably with anesthetic medications.