If you’re going to have a surgical procedure that requires anesthesia, it’s important to disclose cannabis use to your doctor ahead of time, the American Society of Regional Anesthesia and Pain Medicine recommends.
That’s because cannabis products can interact with drugs used before and during surgery and may cause increased pain, requiring the use of more postoperative pain medication, including opioids.
“Even though some people use cannabis therapeutically, studies have shown regular users may have more pain and nausea after surgery,” the society’s President Dr. Samer Narouze says in a medical advisory issued Jan. 3, when the society released the first-ever set of guidelines on cannabis and surgery.
In addition, chronic, heavy users may have a higher risk for heart problems after procedures.
The guidelines did not endorse or oppose cannabis use but were intended to provide evidence-based guidelines for physicians, because anesthesiologists are increasingly coming across patients who have used cannabis.
Among the recommendations are that all patients undergoing surgery should be screened for cannabis use and counseled about possible effects after their procedures.
The document containing the guidelines explains that increases in heart rate and blood pressure can occur for up to two hours after cannabis use. Heavy marijuana smokers may also be at risk for irritation of the airways similar to tobacco smoking. For those reasons, the panel that reviewed the research and proposed guidelines suggested that anesthesiologists consider discouraging cannabis use prior to surgery, as they do tobacco use.
However, the society notes that heavy cannabis users can experience withdrawal symptoms that may complicate anesthesia. The benefits and risks of tapering off cannabis before surgery haven’t been well studied, and the society was unable to make a recommendation about tapering off
The society noted that research on how use might influence anesthesia is limited but suggests that acutely intoxicated patients might require less anesthesia and long-term users might require more. Further research is needed in this area, the society says.
Cannabis and chronic pain
It does appear, however, that cannabis helps people with chronic pain and enables them to use less opioid and other pain medication.
A new study published Jan. 6 in JAMA Open Network found that almost a third of patients used cannabis to manage chronic pain.
Researchers at the University of Michigan, Ann Arbor, and Johns Hopkins Bloomberg School of Public Health surveyed 1,724 adults who live in the 36 states and District of Columbia where medical marijuana is legal and who were experiencing chronic noncancer pain.
Of the subjects who completed the survey, 31 percent reported that they had used cannabis to manage their pain, and more than half who did so said that cannabis use enabled them to decrease their use of prescription opioid and nonopioid and over-the-counter medications. Furthermore, 38.7 percent said cannabis use enabled them to cut back on physical therapy.
“The high degree of substitution of cannabis with both opioid and nonopioid treatment emphasizes the importance of research to clarify the effectiveness and potential adverse consequences of cannabis for chronic pain,” the authors state.
Another study, this one done by researchers at the universities of Minnesota and Colorado, found that adult-use legalization is associated with less alcohol abuse.
The research, published Jan. 12 in the journal Psychological Medicine, also concluded that residents of states where cannabis is legal do not have elevated rates of psychosis.
The study had an interesting design: The researchers assessed 240 sets of identical twins. One of each pair lived in a state where cannabis sales are legal and the other in a state where sales are prohibited.
The finding that the subjects in the legalized states were less likely to engage in behavior associated with alcohol abuse confirms prior studies, the investigators say.
The twins in the legalization states did report a slight uptick in cannabis use — that, too is consistent with previous studies. But the authors did not find a correlation with increased incidences of psychosis or substance abuse disorder.
“Both sets of results are reassuring with respect to public health concerns around recreational cannabis legalization,” the authors conclude.
And finally, Canadian medical marijuana patients reported improvements in their health and quality of life over a 12-month period.
The study, published Jan. 12 in the journal Cannabis and Cannabinoid Research, followed 2,991 medical marijuana patients and found statistically significant improvements in pain, tiredness, anxiety and well-being at three months that was sustained over a year.
Medical cannabis “directed by physicians appears to be safe and effective within three months of initiation for a variety of medical indications,” the researchers at McGill University conclude.