Clearing the Smoke

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Marijuana users had slightly increased pain and more trouble sleeping after surgery.
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Although Canadians have had access to medical marijuana for over 18 years, many questions remain regarding the effects of cannabis and related compounds in the healthcare setting.

In Canada, medical marijuana has been available since 2001. Now that recreational use has recently also become legal, it is expected that hospitals will be treating more and more patients that use marijuana or related compounds known as cannabinoids.

According to surveys, most people believe that cannabinoids would help with the management of pain after surgery, but few studies have been conducted to test if this is true.

To help shed light on the effect of cannabinoids use on surgical outcomes, a team of clinician-scientists at the Krembil Research Institute mined data collected from orthopedic surgery patients.

The database that the researchers used was developed locally by the Acute Pain Service at the Toronto Western Hospital’s Department of Anesthesia and Pain Medicine. Known as NOPAIn (Networked Online Processing of Acute Pain Information), the database provided researchers with pain and related information on 155 patients who used cannabinoids before their surgery for medical or recreational purposes.

When compared to non-users, those who used cannabinoids had slightly higher reported pain intensities in the first 36 hours after surgery. Patients with a history of cannabinoid use were also more likely to experience sleep impairment while recovering from surgery.

“Our results suggest that patients who use cannabinoids may be at risk of a higher intensity of pain after surgery,” Dr. Anuj Bhatia summarizes. “With marijuana use likely increasing in the coming years, understanding the implications for care and the mechanisms of drug interactions will be increasingly important.”

These preliminary observations highlight the need for further studies to identify best practices for those who use cannabinoids—not only for pain and sleep management after surgery but for other treatments and other settings within the healthcare system.

This work was supported by the Department of Anesthesia and Pain Medicine at University Health Network and the Toronto General & Western Hospital Foundation.

Liu CW, Bhatia A, Buzon-Tan A, Walker S, Ilangomaran D, Kara J, Venkatraghavan L, Prabhu AJ. Weeding Out the Problem: The Impact of Preoperative Cannabinoid Use on Pain in the Perioperative Period. Anesth Analg. 2018 Dec 7. doi: 10.1213/ANE.

Dr. Anuj Bhatia, a Clinician Investigator at the Krembil Research Institute, served as a lead author of the study.