I live in California. Marijuana is now legal here. I have patients who ask me frequently if they can use it as part of their recovery.
I focus on your habits only as they relate to my surgery with you. Does it affect healing? Does it affect blood supply? Scarring? Infection rates? Lung function? Does it increase your risk for any complications? Does it interact with anesthesia given during the surgical procedure or the medicines used after? Does it increase or decrease the effects of other medications? How long does it stay in your system? Can you reverse it? Does it matter how you take it? THC vs CBD?
My short answer is I do not know its effects. It has not been well studied.
There is such a litany of different combinations and products. There are creams, oils, vaping, gummies. There are varying degrees of THC and CBD. There are varying concentrations. When I do literature searches in PubMed, which shows published papers across the specialties, I see varying reports. Most are from 2018. That is because this is an evolving field. There are benefits touted with respect to inflammation, anxiety, and pain. But I care about its effect for my surgical patients. The fact it may be good for arthritis does not mean it is okay for surgery. Look at the commonly used, over the counter medication Advil. I cannot have my plastic surgery patients use Advil around the time of surgery, because it increases the risk for bleeds. Advil is commonly used for other surgeries like hysterectomies and knee scopes- but it is not okay for tummy tucks.
Looking at surgical papers I found ones like these:
- A review of the literature “Surgical Considerations of marijuana use in elective procedures” which had a clear recommendation to avoid use within 72 hours of surgery because of heart, lung, and anesthetic issues.
- Results:
In acute settings, marijuana’s effects peaked at approximately 1 hour post initiation, lasting 2-4 hours. Marijuana increased cardiac workload, myocardial infarctions and strokes in young, chronic users. Cannabis caused similar pulmonary complications to those of a tobacco smoker. Marijuana caused airway obstruction and increased anesthetic dosages needed to place laryngeal airways. Use within 72 hours of general anesthesia was advised against. In vitro and in vivo studies were contradictory regarding prothrombic or antithrombotic effects.
- Results:
- One study shows in total knee arthroplasty patients there was a statistically significantly higher infection rate and shorter time to need to revise. It was a retrospective study of over 2.7 million patients.
- Cannabis use was prevalent in 18,875 (0.7%) of TKA patients with 2,419 (12.8%) revisions within the cannabis cohort. Revision incidence was significantly greater in patients who use cannabis (p < 0.001). Time to revision was also significantly decreased in patients who used cannabis, with increased 30- and 90-day revision incidence compared to the noncannabis group (P < 0.001). Infection was the most common cause of revision in both groups (33.5% nonusers versus 36.6% cannabis users).Cannabis use may result in decreasing implant survivorship and increasing the risk for revision within the 90-day global period compared to noncannabis users following primary TKA.
- Another study in bariatric patients showed HIGHER need for postop opiods in marijuana users, but no change in complications.
- “Marijuana’s Influence on Pain Scores, Initial Weight Loss, and Other Bariatric Surgical Outcomes” A total of 434 patients, among whom 36 (8.3%) reported MJ use, comprised the study population. Perioperative opioid requirements were significantly higher in the MJ-user group (natural log morphine equivalents of 3.92 vs 3.52, p = 0.0015) despite lower subjective pain scores (3.70 vs 4.24, p = 0.07). MJ use did not affect percentage of 90-day total body weight loss, development of postoperative complications, or improvement in medical comorbidities.
- “A Systematic Review of the Complex Effects of Cannabinoids on Cerebral and Peripheral Circulation in Animal Models” found conflicting reports on cannabis effect on the blood vessels, but found it can cause stroke and blood vessel constriction.
- They conclude: “Scientific data on the effect of cannabinoids in cerebral vascular regulation in animal models is slim. Evidence has been accumulating with both vasodilation and constriction occurring secondary to cannabinoid exposure and metabolization. Clinical data suggest that cannabinoid uptake may play a role in the etiology of cerebral infarcts, but the underlying mechanisms are unclear. Vasoconstriction may be the common macroscopic endpoint of a multitude of molecular mechanisms triggered by cannabinoids.”
The lists go on and on.
Again, this is a complex issue. We will figure this out. Scientific studies can help us understand its effects and where it ideally should be used. THC vs CBD, concentrations, and route of administration likely need to be looked at separately.
Do not forget cannabis is a drug. Until it is better understood, studies like those above indicate there are issues with cannabis in surgical patients –higher infection rates, revision rates, vasoconstriction (which reduces blood supply), increased need for anesthesia and postoperative dosages, and cardiac effects.