Anesthesia in the News
  • Cannabis Use and Propofol in Endoscopy Procedures

    According to Peery AF et al (2018), there were over 7.7 million endoscopic procedures performed in the United States in 2013. In the intervening years, marijuana use has surged, as laws in many states permit its use, despite it remaining illegal under federal law. The latest data by the Centers for Disease Control and Prevention (CDC) cites marijuana as the most commonly used illegal drug in the US, with approximately 22.2 million users each month.

    The propofol premise

    Endoscopy under propofol sedation has become a routine procedure for colorectal cancer screening as well as for the diagnosis and management of various chronic gastrointestinal diseases such as inflammatory bowel disease and celiac disease. Given the number of patients undergoing an endoscopy annually coupled with the widespread use of cannabis by many patients, understanding the effect of cannabis use on the propofol dose at endoscopy and how it impacts patients undergoing anesthetic management is highly relevant.

    Like any other drug, cannabis has the potential to interact with and affect the efficacy of other concurrently administered medications. However, its effect on anesthesia has not been well-documented beyond small prospective studies, case reports and anecdotal accounts.

    In order to evaluate the association between cannabis exposure and the propofol dose needed to achieve adequate sedation at endoscopy, a small multidisciplinary team of Canadian researchers led by an anesthesia provider conducted a case-control study of individuals undergoing endoscopy at a single outpatient endoscopy clinic in London, Ontario.

    Measures and endpoints

    Recently published in the journal PLoS One, the study enrolled 318 participants slated for colonoscopy and/or esophagogastroduodenoscopy (EGD) between 2014 and 2017

    Cases were defined as individuals with any duration of self-reported inhaled cannabis exposure and were subsequently sub-divided by frequency of cannabis use into the following groups for further analysis:

    • daily users (cannabis use at least 4 out of 7 days per week),
    • weekly users (cannabis use 1 to 2 days per week at least 3 weeks per month),
    • monthly users (cannabis use up to 1 to 2 times per month at least 9 months per year)
    • occasional users (cannabis use less than once every 2 months)

    Cases included all individuals with any self-reported cannabis exposure, while controls included all individuals without any self-reported history of cannabis use. Dose of propofol administered by a single anesthetist was collected on each subject as well as additional demographic and procedure-related covariates.

    The primary endpoint was dose of propofol per kg of weight per minute of procedure. Secondary outcomes included dose of propofol by frequency of cannabis exposure (daily, weekly, monthly, occasional, never), and procedural sedation-related complications. For all analyses, a p-value of <0.05 was considered significant.

    Findings, frequency, and risk

    Three hundred and eighteen participants were included in the study (cases, n = 151; controls, n = 167). Cannabis exposure was associated with an increase in propofol dose (cases 0.33 mg/kg/minute ±0.24; controls, 0.18 mg/kg/minute ±0.11; p<0.0001).

    Cannabis exposure remained an independent predictor of propofol dose on multivariate linear regression accounting for other important covariates (p<0.0001). Importantly, daily cannabis users required a higher propofol dose than weekly or monthly users. Further, three procedural sedation-related complications occurred in the cannabis-exposed group, while none occurred in the unexposed group.

    The researchers wrote “data suggest that cannabis use is significantly associated with the quantity of propofol needed for sedation at endoscopy.”

    More to explore

    The study authors further conclude that, while “further study is needed to better understand the molecular basis for this possible drug-drug interaction…Ultimately, cannabis exposure is significantly associated with propofol dose at endoscopy.” As a follow-on to their work, they propose that “Prospective evaluation and mechanistic studies are needed to further define this relationship.”

    Review all the details of the research findings “High quantities: Evaluating the association between cannabis use and propofol anesthesia during endoscopy,” PLoS One. 2021 Mar 4;16(3):e0248062 at: