Research suggests regular cannabis users may need more anaesthesia for surgery

  • Cannabis users may need double the anaesthetic non-cannabis users do
  • Researchers in Colorado studied 250 patients needing colonoscopies
  • 10% were cannabis users
  • Those 10% needed more than double anaesthetic the non-cannabis users did

A new study from the US has found evidence that regular cannabis users may need more than twice the usual dose of anaesthesia for surgery.

Due to an increase in the number of states which have legalised medicinal or recreational, researchers in Colorado conducted a study to gain a better understanding of whether cannabis can impact the effectiveness of anaesthesia.

In the relatively small study, researchers studied 250 patients who underwent ‘minimally invasive procedures’ requiring anaesthesia.

Twenty-five patents, 10% of the study group, were regular users of cannabis.

Researchers found that these 25 patients required more than twice as much anaesthetic propofol than their non-cannabis user counterparts, 14% more analgesic fentanyl and 20% more of the sedative midazolam.

Discussing the results of the research in an email, lead study author, Dr. Mark Twardowski of Western Medical Associates in Grand Junction, Colorado, said:

“Cannabis users cannot assume that their use will have no effects on their medical care.

“Clearly, the fact that use affects the effectiveness of these three medications certainly raises myriad questions about potential effects on other medications (pain medicines, anxiety medicines, etc.)

“Because cannabis has such a long life in the body, it may take months to ameliorate the effect.

“Patients absolutely need to inform their [health care] providers about cannabis use prior to any procedure.”

Patients absolutely need to inform their [health care] providers about cannabis use prior to any procedure.
– Dr. Mark Twardowski of Western Medical Associates in Grand Junction, Colorado

While the results of the study may be of some concern to cannabis users, the study has limitations, needing more research before any definitive conclusions can be made.

One such limitation noted by researches is that cannabis users may have withheld information about their use during the study, due to a residual negative stigma attached to cannabis use.

Expanding on Dr. Twardowski’s concerns, Dr. Winfried Hauser explained that cannabis users’ need for more anaesthesia is only problematic if patients withhold information about their cannabis use:

“There is only a problem if patients do not tell their doctors that they are consuming cannabis, and if doctors do not know the consequences of cannabis use for anaesthesia.

“Most probably, the number of patients which require increased dosages of anaesthetics because or recreational and/or medical use of cannabis will increase due to legalisation of medicinal or recreational cannabis.”

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