Effect of cannabis use on propofol requirement for ICU sedation

Dear Editor,
Sedation and analgesia in critically ill patients are among the most important aspects of care delivery in the intensive care unit (ICU) [1]. It can be challenging when dealing with critically ill patients who have a history of substance abuse. Cannabis has analgesic, anxiolytic, antiemetic, and antispastic properties and has been in widespread use and abuse for thousands of years globally. Although some published case reports have shown that cannabis users demanded elevated doses of intravenous and inhaled anaesthetics during anaesthesia induction and/or maintenance [2, 3], data regarding cannabis and its interactions with commonly used sedative and analgesic agents in the ICU setting are scarce.
Flisberg et al. [4] in a prospective, randomized, single-blinded human study assessed the induction doses of propofol in patients using cannabis. This study included 30 male cannabis users and 30 control individuals. Induction doses of propofol to achieve the target bispectral index values were not significantly different in the 2 groups. However, in the cannabis user group significantly higher doses of propofol were required to achieve adequate sedation for successful laryngeal mask insertion. The authors concluded that to achieve satisfactory clinical response, higher doses of propofol are required in cannabis users. In addition, Imasogi et al. [5] implemented a case-control study on the correlation between cannabis use and propofol anaesthesia during endoscopy. In total 318 members participated (cases, n = 151; controls, n = 167) in this study. Their results indicated that cannabis exposure was concomitant with a rise in propofol dose. The authors concluded that cannabis consumption was significantly associated with the amount of propofol required for sedation in endoscopy. An animal study Brand et al. [6] showed that Δ 9-Tetrahydrocannabinol (9-THC), the key psychoactive component of the cannabis plant, can significantly reduce the sedative effect of 50 mg kg–1 propofol in mice. Sedation could only be achieved by increasing propofol to toxic doses of 100 mg kg–1. They concluded the existence of an antagonistic interaction between 9-THC and propofol.
We report a 38-year-old, 90 kg male with a history of a few pack-years tobacco smoking and cannabis consumption for over 10 years (with no clear description of its amount) admitted to the ICU postoperatively. There was no significant past medical or surgical history. In a...


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