Cannabis users may need more anesthesia for surgery

(Reuters Health) – An American study suggests that people who regularly consume cannabis may need more than twice the usual dose of anesthesia for surgery.

With an increasing number of US states legalizing marijuana for medical and recreational purposes, more and more patients are using them in operating theaters across the country. To get a better idea of ​​the impact of cannabis on the effectiveness of different types of anesthesia, the researchers studied 250 patients who underwent a minimally invasive procedure requiring anesthesia in Colorado, where the Marijuana use for recreational purposes is legal.

Twenty-five patients, or 10%, reported regular cannabis use. The study found that cannabis users needed more than double the propofol anesthetic compared to other patients. Cannabis users also needed 14% more fentanyl analgesic and 20% more sedative midazolam.

"Cannabis users can not assume that their use will have no effect on their medical care," said Dr. Mark Twardowski, lead author of the study, from Western Medical Associates in Grand Junction, Colorado .

"Clearly, the fact that the use affects the effectiveness of these three drugs certainly raises a myriad of questions about the potential effects on other drugs (pain medications, anti-cancer drugs). anxiety, etc.), "said Twardowski by e-mail.

"Because cannabis has such a long life in the body, it may take months to improve this effect," said Twardowski. "Patients must absolutely inform their providers of cannabis use before any procedure."

Most patients in the study underwent colonoscopy.

Additional research is needed to confirm these preliminary results in a wider population of cannabis users and in patients undergoing a wider variety of surgeries, note the study's authors.

One of the limitations of the study is the possibility that some cannabis users may not have disclosed this information, leaving this information outside of the medical records used by researchers for their analyzes. Although recreational marijuana is legal where the study was conducted, stigma may have prevented some people from reporting it, noted researchers in the Journal of the American Osteopathic Association.

But the results still suggest that doctors need to consider cannabis use when planning patient care and assessing drug needs, the study team writes.

"The problem only arises if patients do not tell their doctor that they are using cannabis and they do not know the consequences of cannabis use for anesthesia," he said. Dr. Winfried Hauser from Klinikum Saarbrucken in Germany.

"Most likely, the number of patients requiring increased doses of anesthetics because of recreational and / or medical use of cannabis will increase due to the legalization of marijuana for medical or recreational purposes," said Hauser, who did not participate in the study. E-mail.

SOURCE: bit.ly/2UmAKV3 Journal of the American Osteopathic Association, online April 15, 2019.