“Cannabis users have higher clinical pain, poorer scores on quality of life indicators, and higher opioid use before and after surgery.”
The US House of Representatives last week voted for the first time on legalizing marijuana at the federal level. Although the Senate seems unlikely to pass, the historic House vote on the More act shows how much public attitudes towards marijuana have changed.
A recent Gallup poll found that 68 percent of the country now favors having legal access to marijuana. Last month voters in four states approved recreational cannabis measures, raising to 15 the number of states where cannabis is completely legal. Thirty-six states have approved it for medical use.
With the increasing acceptance and widespread use of cannabis, healthcare providers need to consider marijuana when treating patients, especially those undergoing surgery.
The Perioperative Pain and Addiction Interdisciplinary Network (PAIN) recently convened a panel of 17 experts to develop new guidelines on the care of cannabis-consuming surgery patients. The result is a set of recommendations that include cannabis weaning before surgery and close monitoring during surgery, particularly for heavy cannabis users.
Because of the potential for cannabis to interfere with anesthesia, the guidelines recommend that patients who use a cannabis product more than 2 or 3 times per day should be considered for tapering or cessation several days before surgery. That includes patients who use more than 1.5 grams per day of smoked cannabis, more than 300 mg per day of CBD oil, or more than 20 mg per day of THC oil. Cannabis users may also need additional medication for postoperative nausea and vomiting.
Research on how marijuana interacts with analgesics and other drugs is very limited. But few studies have shown that caution is necessary.
A recent study at the University of Michigan looked at cannabis use and surgical outcomes in 1,335 adults undergoing elective surgery. About half reported using cannabis medically, recreationally or both. The results are concerning.
“On the day of surgery, cannabis users reported worse pain, more centralized pain symptoms, greater functional impairment, higher fatigue, greater sleep disturbances and more symptoms of anxiety and depression versus non-cannabis users,” the researchers said.
Medication use, including opioids and benzodiazepines, was also higher in the cannabis group. The study authors concluded that “cannabis users have higher clinical pain, poorer scores on quality of life indicators, and higher opioid use before and after surgery.”
Another recent study at the University of Colorado Hospital was smaller and more specific, looking at 118 patients who had surgery for a broken leg. About one-fourth of the patients reported prior cannabis use. Although cannabis use was not associated with a higher dose of the anesthetic propofol during surgery, it was associated with more post-operative pain. Cannabis users also required significantly more pain medication than the control group.
Lead study author Ian Holmen, MD, told Practical Pain Management that it was important for clinicians to ask patients about their cannabis use before any surgical procedures.
“Doctors just need to know if the patient is using marijuana. It doesn’t matter if it’s a day-to-day situation, just to make doctors aware that patients who use marijuana may be different from those who don’t use marijuana after and during surgery,” Holmen said.
Further research is needed to better understand how marijuana use affects surgical outcomes and what this effect may change when different doses of cannabis products are used. But the concerns of the Perioperative Pain and Addiction Interdisciplinary Network appear well-founded. Guidelines for the perioperative management of cannabis use are a necessary and useful step forward as cannabis use becomes more common.