Given the paucity of evidence that suggests cannabis use can affect outcomes associated with surgery, the Perioperative Pain and Addiction Interdisciplinary Network (PAIN) has published consensus recommendations on the perioperative management of cannabis and cannabinoid-based therapies. PAIN outlined its recommendations in a recent online edition of the British Journal of Anaesthesia.
Rationale for the Recommendations
Increased legalization of cannabis across the globe has corresponded with an increase in both medicinal and recreational cannabis use. Research indicates cannabis may offer analgesic effects, but other data suggest cannabis may be associated with issues achieving adequate depth of anesthesia. However, clinical guidance is currently lacking on the perioperative management of cannabis use in patients who are undergoing surgery with anesthesia.
PAIN sought to close this gap by convening a steering committee and 17-member expert panel to review the medical literature and form recommendations regarding perioperative cannabis use. The panel sent draft recommendations to 4 independent reviewers: a surgeon, a nurse practitioner, and 2 patients.
Preoperative Assessment and Planning
The PAIN panel recommended routine screening of patients within the preoperative clinic to determine whether the patient has consumed cannabis before surgery. Daily cannabis intake duration of use should also be estimated, the panel recommended, and method of consumption should be determined.
Clinicians should also screen for cannabis use disorder in patients who report cannabis consumption more than 1 time per day. The PAIN panel recommended consideration of regional anesthesia in patients who do consume cannabis before surgery, as long as this form of pain management is not otherwise contraindicated.
Preoperative Cannabis Weaning
If a patient consumes more than 1.5 g/d−1 of smoked cannabis, more than 300 mg/d cannabidiol (CBD) oil, or more than 20 mg/d tetrahydrocannabinol (THC) oil, clinicians should consider cannabis tapering or cessation, provided there are more than 7 days before surgery.
The PAIN panel suggested that if a person consumes 2 g/d−1 inhaled cannabis, a sensible initial weaning target could be 1.5 g/d−1. Weaning to lower doses or complete cessation could be considered if there is enough time before the surgery, the panel added.
Cannabis weaning should also be considered for patients who consume a cannabis product more than 2 to 3 times per day with an unknown CBD or THC content. Clinicians should encourage these patients to start a cannabis product of a known CBD/THC content and then reevaluate. In contrast, cannabis weaning or cessation should not be considered in these patients 24 hours or less before surgery. The panel did not arrive at a consensus about recommendations for cannabis tapering between 1 and 6 days before surgery.
Postoperative Nausea and Vomiting Prophylaxis
Although cannabinoids may be a useful adjunct in treating chemotherapy-induced nausea and vomiting, limited evidence suggests it can prevent postoperative nausea and vomiting. In addition, some patients who consume cannabis can develop severe refractory cyclic nausea and vomiting caused by cannabinoid hyperemesis syndrome.
The PAIN panel recommended additional PONV prophylaxis for patients who consume more than 1.5 g per day of smoked cannabis, more than 300 mg per day of CBD oil, or more than 20 mg per day of THC oil. Additional PONV prophylaxis should also be considered for patients who consume a cannabis product more frequently than 2 to 3 times per day with an unknown CBD/THC content.
Monitoring and Maintaining Anesthetic Depth
Several research studies suggest cannabis consumption may be associated with increased anesthetic requirements to improve achievement of adequate depth of anesthesia. For instance, some human studies indicate self-reported cannabis users require increased propofol and volatile agents to achieve bispectral index readings less than 60.
According to this knowledge, the PAIN panel suggested some cannabis users may require additional anesthetic to achieve adequate depth of anesthesia during induction and maintenance of the anesthesia. In addition, the panel indicated that these patients may also have higher postoperative analgesic requirements.
This recommendation also applies to patients who consume more than 1.5 g/d−1 of smoked cannabis, more than 300 mg/d CBD oil, or more than 20 mg per day of THC oil, as well as to patients who consume a cannabis product more than 2 to 3 times per day with an unknown CBD/THC content.
Postdischarge Contact With Cannabis Authorizer
In an effort to improve postsurgical outcomes after discharge, the panel recommended that perioperative care providers should include a patient’s cannabis authorizer in the discharge planning. Cannabis authorizers may be nurse practitioners, general practitioners, oncologists, or pain physicians. This recommendation was made primarily for patients on higher doses of cannabis as well as patients who had been weaned off or substituted high cannabis doses.
According to the PAIN panel, there is a need for more randomized controlled trials examining patients who consume cannabis in the perioperative period, as this will help inform future guidance. In addition, the panel noted additional study is required to track perioperative outcomes among users of cannabis products. The panel also added that as both existing and new “cannabis preparations are used and the evidence regarding them grows, these guidelines will require review and regular updating.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Ladha KS, McLaren-Blades A, Goel A, et al. Perioperative Pain and Addiction Interdisciplinary Network (PAIN): consensus recommendations for perioperative management of cannabis and cannabinoid-based medicine users by a modified Delphi process. Published online October 28, 2020. Br J Anaesth. doi: 10.1016/j.bja.2020.09.026