Cannabis Use Disorder and Perioperative Outcomes: A Growing Concern

The increasing prevalence and legalization of cannabis use have raised important questions about its impact on patients undergoing surgery. Cannabis use is generally perceived as harmless by the public. In reality, the safety and efficacy of anesthesia and surgery in patients who use cannabis, particularly those with cannabis use disorder (CUD), are subjects of ongoing research and debate.

As cannabis becomes more accessible and socially acceptable, understanding its effects on perioperative outcomes is essential for optimizing patient safety and surgical success. Previous research has identified some of the impacts of cannabis use on surgical patients:

• Cannabis users require higher anesthetic doses to achieve the same degree of sedation as nonusers.^1,2
• Cannabis users have higher pain scores and opioid requirements after surgery.^3,4
• Cannabis users have increased rates of postoperative nausea and vomiting.⁵

Given the increasing prevalence of cannabis use in the surgical population, understanding its implications on perioperative outcomes is critical for patients, surgeons and anesthesiologists. The results of a recent study of elective inpatient surgeries contribute to understanding the harmful associations between cannabis use and perioperative outcomes.⁶ The study focused on CUD—chronic and problematic cannabis use—which may have distinct consequences on perioperative outcomes compared with occasional recreational use. This observational cohort study extracted data from the federal National Inpatient Sample database to pair 6,211 hospitalization records of CUD patients (representing an estimated 31,055 hospitalizations nationally) with hospitalizations similar to those without CUD. Comparing the two groups, CUD was associated with an approximately 20% higher risk for perioperative morbidity and mortality (adjusted odds ratio, 1.19; 95% CI, 1.04-1.37; P=0.01).⁶ Perioperative morbidity and mortality included the following major complications: myocardial ischemia, stroke, acute kidney injury, respiratory failure, venous thromboembolism, infection, procedure-related complications and in-hospital death. Although CUD was not associated with prolonged hospital stays, patients with CUD had higher hospitalization costs, highlighting the real-world impact of heavy cannabis use and consequent complications on increased resource utilization.

To provide context to this study’s findings, the 1.2% absolute increase in perioperative complication rate (from 6.6% in patients without CUD to 7.7% in CUD patients) is similar to the effects of tobacco smoking on perioperative complications. A study by Turan et al found a major morbidity rate of 4.5% in current smokers compared with 3.7% in nonsmokers—a 0.8% absolute increase—with even more pronounced effects among heavy smokers.⁷

Furthermore, the findings of the study clinically corroborate some of the predicted effects of cannabis use based on its mechanisms of action on different organ systems⁸:

• Vasospasms in coronary and cerebral vessels can contribute to myocardial ischemia and strokes.
• Immunosuppression can lead to increased infections and poor surgical wound healing.
• Inhaling cannabis introduces respiratory irritants and triggers airway hyperreactivity.
• Smoking cannabis, particularly with prolonged deep inhalation, can lead to higher carboxyhemoglobin levels.
• Both endocannabinoids and general anesthetics modulate gamma-aminobutyric acid, explaining some of the anesthetic drug interactions observed in heavy cannabis users.

Implications for Perioperative Care

The study’s results raise safety concerns about the perioperative care of heavy cannabis users, necessitating adjustments to anesthesia practices and protocols. Anesthesia providers must be well informed about the potential risks associated with cannabis use, particularly CUD, and integrate this knowledge into their perioperative management strategies.

Although the associations between cannabis use and adverse health outcomes are concerning, more research is urgently needed to clarify different thresholds of cannabis use and their implications for patient safety during surgery. Despite increasing acceptance, the current federal status of cannabis as a Schedule I drug (drugs with a high potential for abuse and no currently accepted medical purpose) limits the ability to produce effective research, thus delaying this clarification. The results from Potnuru et al reinforce the importance of candid patient–doctor discussions regarding cannabis use before surgery. With three in 10 cannabis users developing clinically significant CUD, preoperatively quantifying cannabis is an essential component of the preanesthetic evaluation. By better understanding the potential benefits and harms of cannabis use, anesthesia providers can develop evidence-based perioperative care plans that prioritize patient safety and optimize surgical outcomes.

Of note, much of the research regarding this topic has failed to quantify the amount of cannabis consumed, further contributing to the current ambiguity surrounding perioperative cannabis use. The American Society of Regional Anesthesia and Pain Medicine recently published guidelines for the perioperative management of patients who use cannabis.⁹ They recommend that perioperative clinicians screen all patients for cannabis use before surgery. Clinicians should inform heavy cannabis users about the potential poor response to postoperative pain and nausea control. Patients should be asked about the route, time of last use and frequency/amount of cannabis use. Further, these guidelines recommend that anesthesiologists prepare to alter their anesthesia plan or postpone a procedure if heavy cannabis use compromises patient safety. Similarly, advisories by Ladha et al suggest that tapering or stopping cannabis use may have benefits for those who consume more than 1.5 g per day of smoked cannabis, 300 mg per day of CBD oil and 20 mg per day of THC oil, provided there are seven days or more before surgery.¹⁰ They also recommend increased consideration for regional anesthesia in this population. These recommendations and advisories further support quantifying cannabis use in patients before surgery.

As the landscape of cannabis use evolves, healthcare providers, facility administrators and payors must stay informed of its effects on patient health, particularly in the context of surgery. Encouraging patients to discuss their cannabis use with physicians openly is essential in promoting informed decision making and ensuring comprehensive perioperative care. A proper preoperative evaluation for cannabis use can serve as a unique opportunity not only to screen and potentially diagnose CUD but also to consider lifestyle changes and interventions toward cutting back on cannabis use. In this way, standardized screening for cannabis use in every surgical patient (by anesthesiologists, primary care physicians or surgeons) can have a broader impact on public health by introducing earlier recognition and potential treatment of substance use disorders.

By integrating the latest consensus recommendations and evidence on the risks of heavy cannabis use into clinical practice, the anesthesia care team can proactively address the challenges posed by patients with CUD, mitigate risks, and deliver safe, effective and personalized perioperative care.

References

1. PLoS One. 2021;16(3):e0248062.
2. J Am Osteopath Assoc. Published online April 15, 2019. doi:10.7556/jaoa.2019.052
3. Anesth Analg. 2019;129(3):874-881.
4. Eur J Anaesthesiol. 2019;36(9):705-706.
5. BMC Anesthesiol. 2020;20(1):115.
6. JAMA Surg. Published online July 5, 2023. doi:10.1001/jamasurg.2023.2403
7. Anesthesiology. 2011;114(4):837-846.
8. Proc (Bayl Univ Med Cent). 2019;32(3):364-371.
9. Reg Anesth Pain Med. 2023;48(3):97-117.
10. Br J Anaesth. 2021;126(1):304-318.