Anecdotal evidence suggests that cannabis users require more anesthetic at the beginning of surgery than those who do not use the substance. As such, researchers set out to find whether this is the same across all anesthetic types or just specific varieties.
For their study, the researchers reviewed medical records from 118 patients from the same hospital in Colorado who had surgery for a broken leg between January 2015 and November 2019. All patients had unilateral tibia fractures and had open reduction and internal fixation (ORIF) with intramedullary nail (IMN).
This surgery was selected as it requires a postoperative stay in the hospital, meaning the researchers were able to track postoperative opioid use and patient's pain rankings on a standardized pain numeric rating scale.
The researchers also analyzed the cohort for cannabis use, which was determined through self-reports prior to the study. They were unable, however, to record the type of cannabis consumed, nor its method of ingestion. Nevertheless, just over a quarter (25.4%) of subjects reported cannabis use before surgery.
All in all, the researchers found that while cannabis use was not associated with a higher dose of induction propofol (taken to induce anesthesia), on average, cannabis users required higher levels of intraoperative sevoflurane than those who did not use the substance.
Cannabis use was also linked to higher pain scores in both the post-anesthesia care unit (PACU) and in the inpatient setting. As such, cannabis users required significantly more pain medications than those in the control group, although they did not spend a significant amount of time longer in surgery or in inpatient care.
The lead author of the study, Ian Holmen, MD, says that while interesting findings, his study was made up of 118 case studies rather than a controlled trial and thus requires further research to be conclusive. He nevertheless called the study 'hypothesis-provoking'.
Sources: Practical Pain Management