Research shows that a combination of anesthetic and cannabis can complicate surgical procedures and surgery-related outcomes.
Undergoing a surgical procedure is worrisome for anybody. Some might consider easing their nerves with cannabis. Regular cannabis consumers should think twice, however. Preliminary evidence suggests that anesthetic and cannabis is a bad combination, potentially leading to poor physical and even psychological, outcomes.
Consuming Cannabis Means More Anesthetic Needed During Surgery
In a study published in the Journal of the American Osteopathic Association (2019), the researchers retrospectively investigated whether regular cannabis consumption had any effect on the amount of medication needed for sedation during endoscopic procedures. The researchers reviewed two-hundred and fifty medical records from one endoscopy center located in Colorado, which legalized state-wide recreational cannabis in 2012. They compared the records of patients who regularly consumed cannabis to the records of those who did not.
The findings suggested that regular cannabis consumers required a significantly higher dose of anesthetic for sedation compared to non-consumers.[1]Twardowski, M. A., Link, M. M., & Twardowski, N. M. (2019). Effects of cannabis use on sedation requirements for endoscopic procedures. Journal of the American Osteopathic Association, 119(5), … Continue reading Specifically, the patients required an additional 14 percent fentanyl, approximately 20 percent more midazolam, and a staggering two-hundred and 20 percent increase in propofol. The results persisted when the researchers adjusted for factors of age, sex, alcohol use, and other drugs.
The lead researcher on the project, Dr. Mark A. Twardowski clarified that the research does not suggest that people should avoid consuming cannabis. Twardowski said that “It suggests that the use is not without consequences. One consequence is that more medications may be required for procedures. This increased dose may put people at a higher risk for respiratory suppression during endoscopy procedures.” Other research has demonstrated the negative effect that consuming cannabis immediately before surgery can potentially have on psychological outcomes.
Anesthetic and Cannabis Induces a Shallower Depth of Anesthesia
In a study published in Harefuah (2018), the researchers assessed the impact of cannabis on the depth of anesthesia during surgery.[2]Ibera, C., Shalom, B., Saifi, F., Shruder, J., & Davidson, E. (2018). Effects of cannabis extract premedication on anesthetic depth. Harefuah, 157(3), 162-166. The depth of anesthesia, or how ‘under’ a patient is during surgery, is measured by the bispectral index (BIS).[3]Health Quality Ontario. (2004). Bispectral index monitor: an evidence-based analysis. Ontario Health Technology Assessment Series, 4(9), 1-70. A BIS monitor, which consists of a sensor, a digital signal converter, and a monitor, quantifies changes in the electrophysiologic state of the brain during anesthesia. In patients who are awake, a standard BIS score is 90 to 100. Lower numbers represent a higher hypnotic effect, with a BIS value below 60 associated with a low probability of response to commands.
The researchers randomized 27 patients undergoing elective orthopedic surgery into individual groups receiving: 1) high dose cannabis, 2) low dose cannabis, 3) active placebo, or 4) placebo. Patients received their dose of cannabis or placebo medications 20 minutes before going under general anesthesia in a double-blind fashion.
The researchers found that in the high dose cannabis treatment group there were significantly higher BIS scores compared to the other groups. These findings, in combination with those highlighted in the previously mentioned 2019 study, demonstrate the importance of continued exploration of cannabis and anesthesia-related outcomes. Along with physical complications, when anesthesia is too light, there can be an increased recall of events or conversations that occur in the operating room. This increased recall is sometimes frightening for patients and can lead to negative psychological outcomes, such as PTSD.
Cannabis Can Lead to Complications Following Surgery
Depending on the type of surgery and cannabis consumption method, certain complications are more likely in regular cannabis consumers following a surgical procedure. Although some research suggests that cannabis smoking is safer than tobacco smoking, a higher level of risk remains. Regular cannabis consumption can increase the amount of time a patient needs to be on a ventilator following surgery. Furthermore, cannabis consumers may have a greater risk of developing pneumonia and more prominent scarring of incisions.
Post-operative outcomes might be dependent on whether a patient smokes their cannabis, but more research is needed to determine if that is true for other routes of administration. Like so many other cannabis avenues, research exploring the relationship between anesthetic and cannabis is only just beginning.
Why You Should Tell Your Doctor
Based on this lack of current evidence, it is difficult to determine how much cannabis is too much, or how far ahead of surgery an individual should cut off their cannabis consumption.
However, in all cases, it is important to disclose cannabis consumption practices to your medical team. This could include your family physician, anesthesiologist, and surgeon. Although the evidence is scarce, the preliminary evidence suggests that the interaction between anesthetic and cannabis can complicate surgery and surgery-related outcomes.
Furthermore, research has demonstrated that drug interactions with cannabis can be dangerous in every-day life.[4]Damkier, P., Lassen, D., Christensen, M. M. H., Madsen, K. G., Hellfritzsch, M., & Pottegård, A. (2019). Interaction between warfarin and cannabis. Basic & Clinical Pharmacology & … Continue reading Doctors only know what their patients tell them. Therefore, without key cannabis-related information, patients can be at risk for serious health complications, or even death.
Some patients might be hesitant to disclose cannabis consumption practices. This is especially true in countries or states without legalized cannabis. But it is important to remember that doctors are bound by doctor-patient confidentiality. You are much safer under the knife and in the rest of your life if your doctor is aware of your cannabis consumption.
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