Physicians should ask all patients undergoing surgery about their cannabis use, including how often, how it’s consumed and why, according to a new guideline from the American Society of Regional Anesthesia and Pain Medicine (ASRA).
This is believed to be the first U.S.-based guideline on perioperative management of cannabis, and the recommendations cover preoperative, intraoperative and immediate postoperative care considerations.
“Before surgery, anesthesiologists should ask patients if they use cannabis—whether medically or recreationally—and be prepared to possibly change the anesthesia plan or delay the procedure in certain situations,” said Samer Narouze, MD, PhD, the senior author and president of ASRA.
As more states loosened regulations on recreational cannabis over the past decade, anesthesiologists noticed that a minority of patients who are long-term users of cannabis have more nausea and pain postoperatively, and may require more medications to manage discomfort, said Dr. Narouze. He is also the chairman of the Center for Pain Medicine at Western Reserve Hospital, in Cuyahoga Falls, Ohio.
Enhancing Communication Is Key
The guideline was developed by a 13-member committee set up by ASRA, and included anesthesiologists, chronic pain physicians and a patient advocate. After reviewing the published evidence, the group made 21 recommendations, which were published in January in Regional Anesthesia & Pain Medicine, ASRA’s official publication (2023 Jan 3;rapm-2022-104013).
Four recommendations are categorized as Grade A, meaning they are backed by the highest levels of evidence. They include a call for physicians to screen all patients for cannabis use before surgery. In patients who have altered mental status or impaired decision-making capacity from cannabis use at the time of surgery, procedures should be postponed for two hours if possible.
Chronic users of cannabis should also be counseled on the potentially negative effects of cannabis on postoperative pain control, and pregnant patients should be warned about the risks of cannabis use to the fetus, according to the guideline.
Patients often fail to disclose details of their cannabis use to physicians preoperatively, Dr. Narouze said. Some patients do not report it because they worry about being judged, especially in states where recreational cannabis has not been decriminalized. Others do not reveal use because physicians generally ask about illicit drugs, rather than cannabis specifically.
The guideline is designed to improve communication between patients and physicians, he said.
“We need to ask direct questions in a compassionate, confidential way, and tell the patient that this is for the sake of having a good outcome from surgery,” Dr. Narouze said.
Cannabis Use Increases
About 10% of the U.S. population now uses cannabis at least monthly. According to the National Organization for the Reform of Marijuana Laws, 37 states and the District of Columbia have laws permitting marijuana for medical use, and 21 states have legalized recreational use. Of these, 10 have changed their laws since 2020.
Nevertheless, the body of evidence about cannabis consumption and its effect on surgical patients is still too small, the reviewers noted.
But there’s no question that cannabis use immediately before surgery is harmful, according to the ASRA guideline. People who have smoked or ingested cannabis will often have altered mental status and impaired decision-making capacity for several hours, affecting their ability to give informed consent. Smoking cannabis can increase heart rate and blood pressure for one to two hours and, in rare cases, lead to a higher risk for perioperative acute myocardial infarction. Smoking cannabis can also increase airway resistance and respiratory adverse events, the committee found.
They recommended postponing elective surgery for a minimum of two hours after cannabis use.
A “moderate” level of evidence shows that long-term cannabis consumption may worsen postoperative pain, increase postoperative opioid use and lead to postoperative hyperalgesia. The ASRA guideline said frequent cannabis users should be warned about these potential effects, but the organization stopped short of calling for tapering of cannabis and cannabinoids in the perioperative period.
Low-dose, medically supervised cannabis use likely has a lower risk for negative effects, the committee added.
The guideline comes at a time when a growing number of patients say they are using cannabis to help manage pain and decrease their use of prescription opioids and over-the-counter pain medications.
The authors acknowledged that the relationship between cannabis use and opioid use is complex and poorly understood. There is insufficient evidence to make recommendations about cannabis’ effect on pain or the need for postoperative opioids, they wrote.
Mark Bicket, MD, PhD, an assistant professor at the University of Michigan, in Ann Arbor, said the guidelines are “appropriately balancing the lack of high-quality evidence that we have, while at the same time trying to make sure that providers have some guidance and patients can go through their operative experience with the least amount of harm relative to cannabis use.”
Dr. Bicket authored a study that found more than half of cannabis users said they required less opioids because of their cannabis use (JAMA Netw Open 2023;6[1]:e2249797).
A key issue for anesthesiologists caring for patients who have short- or long-term exposure to cannabinoids is to determine what adjustments, if any, are needed regarding doses of routine perioperative medications.
The Perioperative Pain and Addiction Interdisciplinary Network recently recommended that physicians encourage perioperative cannabis weaning in elective surgery patients, and take additional care in monitoring and maintaining anesthetic depth for patients who are chronic cannabis users (Br J Anaesth 2021;126[1]:304-318).
ASRA’s recommendation was less definitive in light of the “overall weak quality of evidence and absence of RCTs [randomized controlled trials],” the authors noted. The effect of preoperative cannabis use needs to be investigated further, but limited evidence suggests that it may have an effect on lowering anesthetic requirements in the acutely intoxicated user and increasing anesthetic requirements in the long-term regular user, they added.
This article is from the March 2023 print issue.