Screen All Surgery Patients for Cannabis Use, New Guidelines Say

Surgical candidates undergoing anesthesia should be screened universally for cannabis use, new guidelines from the American Society of Regional Anesthesia and Pain Medicine (ASRA Pain Medicine) stated.

Anesthesiologists should ask all patients about the type of cannabis product used, whether it was smoked or ingested, the amount used, how recently it was used, and the frequency of use, reported Shalini Shah, MD, of the University of California Irvine, and colleagues in Regional Anesthesia & Pain Medicine.

Anesthesiologists also should be prepared to possibly change the anesthesia plan or delay surgery, the authors noted. They should let patients know that regular cannabis users may have more pain and nausea after surgery and may need more medications to manage post-surgical pain.

The guidance is the first in the U.S. about cannabis and perioperative management.

Cannabis is the most commonly used recreational drug in the U.S. and the most commonly used psychoactive substance after alcohol, noted guideline co-author and ASRA Pain Medicine president Samer Narouze, MD, PhD, of Northeast Ohio Medical University in Akron.

About 10% of the population -- 27.6 million people -- reported monthly use in 2017, according to data from the Substance Abuse and Mental Health Services Administration (SAMHSA) and that number is growing, Narouze added. Recent Gallup poll numbers place the number of Americans who smoke marijuana at about 16%.

"That's why we've been working on these guidelines for the last 2 years, because we have millions of people using cannabis recreationally or medicinally," Narouze said in an interview with MedPage Today.

"Every day, people who use cannabis present for surgery," he pointed out. "We've seen some observational studies about this in the literature, but there have been no randomized control trials."

But even in observational studies, patterns were clear, Narouze noted."The main issue we're seeing is more pain in recovery and more nausea and vomiting, also in recovery," he observed.

"We also saw associations with increased risk for post-operative cardiovascular morbidity -- post-operative myocardial infarction and arrhythmias -- and post-operative cerebrovascular morbidity in some patients," he said.

Cannabis had varying interactions with anesthetics and sedatives, Narouze added. Some patients also experienced post-operative cannabis withdrawal symptoms.

The guidelines stemmed from a literature review and other work from the ASRA Pain Medicine guideline committee. A consensus recommendation required at least 75% agreement of the committee's 13 experts.

The committee used the U.S. Preventive Services Task Force (USPSTF) process of assigning an A, B, C, or D letter grade (or I for insufficient) based on evidence strength.

Recommendations receiving an A grade included screening all patients before surgery, postponing elective surgery if patients had altered mental status, counseling heavy users about potentially negative effects of cannabis on post-operative pain control, and counseling pregnant patients on risks associated with cannabis use.

Those receiving a B grade were counseling patients on potential perioperative risks associated with continuing cannabinoids and discouraging cannabis use during pregnancy and immediately after childbirth.

C grade recommendations included delaying elective surgery for at least 2 hours after patients smoked cannabis, adjusting anesthesia delivery based on symptoms and timing of last cannabis consumption, increasing vigilance of potential heart and neurological problems after surgery, using multimodal pain control including opioids if needed, and using a cannabinoid agonist like dronabinol to treat severe cannabis withdrawal symptoms post-operatively.

"There's a large gap in our knowledge about cannabis and surgery," Narouze stated. "That's why most recommendations did not reach the grade A level."

"However, we do not want to underestimate the information we gather from observational and large data studies, because this is real-world data," he said.

The ASRA Pain Medicine task force will continue monitoring new research as it becomes available, Shah and colleagues noted. The group may revise the entire document or specific sections if new evidence warrants updated recommendations.

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