A new study suggests that cannabis users may require more anesthesia during surgery than non-users. It also finds that cannabis users may experience increased pain afterwards, and use higher doses of opioids in the hospital. Researchers presented the results today at the American Society of Anesthesiologists’ annual meeting, Anesthesiology 2020.
The new study was the first to compare the effects of cannabis among users and non-users during and after surgery. It adds to the growing body of research showing that patients who use cannabis need more anesthesia and have more surgery-related pain. In this stuy, all patients underwent surgery for a broken leg.
“There is some evidence that cannabis may be beneficial for chronic and nerve pain,” said the study’s lead author Ian Holmen of the University of Colorado Hospital, Aurora. “However, early research suggests that this is not the case for acute pain such as for surgery of a broken leg.”
Exaggerated pain responses
“We now understand patients who chronically use opioids prior to surgery often have exaggerated pain responses and need increased pain medication after surgery because they have an increased tolerance,” he said. “We speculate that cannabis use may cause a similar effect, but we need more research to determine if this is the case.”
The researchers looked at 118 patients in Colorado who were undergoing surgery to repair a fractured tibia (shin bone). The researchers defined “cannabis use” as a patient self-reporting any quantity of use prior to surgery. For this study, 25.4% of patients fit into this category.
The researchers then compared the two groups (users vs. non-users), assessing the amount of anesthesia provided during surgery. They also measured patients’ reported pain scores, and the amount of opioids they consumed in the hospital after surgery.
They study found that patients who had used cannabis reported higher pain scores while in recovery. Users averaged a score of 6, as opposed to 4.8 for non-users. These scores are based on the patient’s self-assessed level of pain. A score of 0-3 means little to no pain, 4-7 is moderate but tolerable pain, and 8-10 is severe pain.
Cannabis and opioids
Cannabis users also used 58% more opioids per day while in the hospital. They averaged 156 “morphine milligram equivalents” (MME) per day versus 99 MME per day for non-users.
Anesthesiologists typically increase the level of anesthesia during surgery based on their observations of the patient. Signs such as involuntary body movements, increased heart rate, high blood pressure, or increased breathing rate indicate the patient may be experiencing more pain.
Researchers did not include patients who suffered from chronic pain, or those whose health system records indicated they had previously used prescription opioids.
“This study shows that it is important for patients to tell their physician anesthesiologist if they have used cannabis products prior to surgery,” said Holmen, “to ensure they receive the best anesthesia and pain control possible, including the use of non-opioid alternatives.”
“It also confirms that more research is needed to understand how cannabis impacts pain,” Holmen said.
Study: “Cannabis Use Is Associated With Increased Intraoperative Anesthetic And Postoperative Opioid Consumption In Isolated Tibia Fracture Repair“
Authors: Ian C Holmen, Jeffrey P Beach, Alex M Kaizer, Ramakrishna Gumidyala
Publication date: October 5, 2020
Photo: by Andrea Piacquadio from Pexels
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