A Duke University School of Medicine medical review has warned cannabis users may require higher doses of the anaesthetic propofol during surgery.
Medical cannabis is legal in 40 of 50 US states and 24 states for recreational use. And even where it isn’t, it is still widely consumed. The increasing use of cannabis, whether for medicinal or recreational purposes, presents extra challenges for anaesthetists.
Propofol is a common anaesthetic that works by depressing the central nervous system. It has a rapid onset and quick recovery. But the Duke researchers says cannabis users may require higher doses for proper sedation, with some cases requiring a 15% to 30% higher dose than those needed in non-cannabis users.
However, a major challenge is there’s no consensus on how much cannabis use may alter propofol’s effectiveness, making surgeries and procedures riskier — particularly given its impact on heart function. It’s still not clear how compounds in cannabis such as tetrahydrocannabinol (THC) and cannabidiol (CBD) may change how the body responds to anesthesia.
“Further research is needed to corroborate causality, confirm and guide dose adjustment needs, determine perioperative cannabis tapering effects, and elucidate the underlying explanatory mechanisms to establish precise clinical guidelines and ensure patient safety,” states the review, which has been published in the journal Current Opinions in Anesthesiology.
And generally speaking, lead author Ruba Sajdeya, MD, PhD, reminds health professionals cannabis use is a relevant factor in anesthesia planning.
“We’re urging clinicians to ask about it routinely and plan accordingly.”
The authors also warn some patients may hesitate to reveal their cannabis use due to lingering stigma, or not considering it worth mentioning before surgery.
There are also implications for cannabis users post-surgery. In 2023, the American Society of Anesthesiologists published a patient guide, which in part states:
“Research shows that people who use cannabis regularly may experience more pain and nausea after surgery than those who do not use cannabis. Prolonged exposure to cannabis may create this higher sensitivity to pain because cannabinoid receptors in the spine are in the same area as opioid receptors.”
