Russell: Marijuana research is unlike any other drug research. Researchers have to jump through a lot of hoops with the federal government to study it. As a result, people are using marijuana before there is enough science to prove safety and efficacy.
We don’t have the data we should because the federal government has classified marijuana as a Schedule I Controlled Substance—the same category as heroin. This means it is considered to have no accepted medical value and a high potential for abuse, not because there is research proving this, but because there is little research at all on cannabis.
The lack of research is because Schedule 1 Controlled Substances have great governmental restrictions on studying them. Researchers must apply to three different federal government agencies to obtain marijuana for their studies. The supply is also limited because the University of Mississippi is the only US facility permitted to grow marijuana for research purposes, and there is a cap on the amount that can be grown and released.
Russell: As marijuana legalization and use have increased, the NCSBN (National Council of State Boards of Nursing) has received frequent questions about the care of patients who use marijuana. NCSBN researched and published the National Nursing Guidelines for Medical Marijuana (sidebar, right), which include a comprehensive literature review and evidence-based national nursing guidelines for medical marijuana.
The American Association of Nurse Anesthetists is also working to establish formal guidelines for caring for patients who use marijuana.
Schick: The main psychoactive chemical in marijuana is THC (delta-9-tetrahydrocannabinol). THC is the component that gets users “high.” The main non-psychoactive component is CBD (cannabidiol).
Recreational users often choose smoking or edible products with high levels of THC and lower levels of CBD to achieve a high rather than to ease a chronic condition.
Russell: People with many conditions may be using CBD and/or other marijuana products to control their symptoms. There are 57 qualifying conditions across US medical marijuana programs, including neuropathy, chronic pain, chemotherapy-induced nausea and vomiting, and spasticity caused by multiple sclerosis.
Russell: The active components of marijuana are available in a wide variety of forms and products, including tinctures, edibles, skin oils, lozenges, chewing gum, and raw marijuana that can be smoked or vaped. Labeling of products can be inconsistent or inaccurate, and any of these products may contain varying amounts of cannabinoids (THC, CBD, or cannabinol). All cannabis products should be used on a “start low, go slow” basis with patients keeping a log of the timing, amount of use, and the control of symptomology.
Russell: Adverse effects of cannabis are influenced by a patient’s condition and current medications. Cannabis may exacerbate symptoms associated with asthma, bronchitis, emphysema, cardiac disease, and alcohol or drug dependence. It can also aggravate illnesses that cause cognitive deficits and issues with balance and posture, such as tardive dyskinesia. It may also worsen severe liver and kidney disease.
High concentrations of THC may promote seizures in patients who have seizures. Chronic users can also develop hyperemesis, including severe cyclic nausea and vomiting.
Schick: Smoking marijuana is associated with large airway inflammation, increased airway resistance, and lung hyperinflation. It can also cause inflammation of the uvula, called uvulitis. This can make intubation difficult and result in a lot of swelling in the posterior pharynx postoperatively.
Eisenbarth: Cannabis effects are inconsistent because of the varying amounts of use, dosing, and marijuana plant preparations. The effects also differ between acute and chronic use as tolerance is created.
An acute, occasional user will experience more side effects that could be of concern perioperatively, such as blood pressure, heart rate, and cognitive changes. However, anyone who smokes marijuana might have respiratory effects that could be troubling in the perioperative area, such as increased sputum production, chronic bronchitis, and airway edema.
Patients using vaping and edibles don’t appear to have respiratory effects, although the long-term effects of vaping on the lungs and airway are not known yet.
Because cannabis interacts with common anesthetic medications, acute and recreational users may suffer more deleterious physiologic effects of concern to the anesthesia provider.
There are also older reports indicating that acute cannabis intoxication might increase myocardial oxygen demand, increasing the risk of cardiac events perioperatively.
More current research has found that this risk only applies to patients already at risk. Reports vary, but there is also some concern about a potential increased risk for stroke and TIA (transient ischemic attack) because of a reduced circulatory response. This is less likely in the chronic user and more likely in patients who are already susceptible.
Schick: We have found that patients who regularly use marijuana products with THC require more opioids to control their postoperative pain. In addition, acute use of cannabis may require more anesthetic because there is greater catecholamine release. Chronic users may require less anesthetic because of catecholamine depletion.
Russell: Cannabinoid receptors are absent in the cardiorespiratory centers in the brainstem, so this is believed to preclude the possibility of a fatal overdose. However, research is so limited that we can’t say that definitively.
Russell: Smoking or vaping marijuana produces effects almost immediately, peaks in about 30 minutes, and then tapers off in about 3 to 4 hours. Edible products can take 30 minutes to 2 hours to produce effects.
Schick: Nurses should understand that people who are using cannabis regularly are probably still going to use it before surgery. They need to have this awareness, make the assessment, and communicate any cannabis usage to the anesthesia provider, who should weigh the risks and possibly postpone surgery.
Nurses will often ask if a patient has used herbs or supplements, but patients may not think of marijuana as an herb. Nurses need to ask specifically about marijuana and any cannabis products, such as CBD. Then they need to document concisely, including type, route, dosage and frequency.
For example, simply documenting that a patient uses marijuana does not indicate whether the patient is chronically smoking marijuana with a high level of THC or using CBD skin oil with a low level of THC for arthritis pain.
It’s a good idea to add specific questions about cannabis use to the preoperative assessment of all patients (sidebar at right).
Eisenbarth: In an effort to provide the safest and best care for patients, providers must weigh the potential harm with the potential benefit for cannabis abstinence.
For some chronic users, it may be best for them to stay on their dosing schedule before surgery to avoid withdrawal symptoms.
Withdrawal symptoms can include:
• agitation, irritability, and aggression
• craving, which is similar to nicotine craving
• muscle cramps
Certified registered nurse anesthetists should consider the possibility of withdrawal during anesthesia induction and emergence, and nurses in the postanesthesia recovery unit (PACU) can anticipate that patients who have withdrawal symptoms might need more PACU time. It can be more difficult to control their postsurgical pain, and they may also experience a return of the symptoms treated by cannabis.
Symptoms may include:
Eisenbarth: Nurses should advise patients to avoid smoking marijuana before undergoing surgery because of the risk of airway complications. To avoid withdrawal, there are lower-risk options including vaping, chewing cannabis gum, or sucking on a cannabis lozenge. These methods also allow patients to maintain NPO status by avoiding the ingestion of edibles, such as brownies.
Eisenbarth: The American Surgical Association says that if a patient appears intoxicated and unable to sign a consent, then he or she is unable. If a patient is cognitively normal and appears to have competence, he or she can sign informed consent. This makes it critical to perform and document a mental status evaluation before a consent is signed by a patient who uses marijuana.
Russell: Currently, there is no lab value that will tell you if someone who uses marijuana is impaired or at risk for surgery. This is because THC is a fat-soluble substance and does not have a predictable exit from the body as does alcohol, a water-soluble substance. Novice users may have THC in their blood tests for a week to 10 days after ingestion. Chronic users can test positive for a month or more since their last use. Therefore, drawing a THC level is not useful preoperatively in determining if a person is too impaired for surgery or to sign a consent.
Eisenbarth: Medicinal users may be using products with a high CBD concentration and low THC concentration, so they may have fewer adverse effects of THC. However, the amount of THC in CBD products can vary greatly.
Some people believe that patients who use only CBD products with a low THC concentration generally don’t experience withdrawal symptoms, but definitive evidence of this theory is lacking. Because of this, it is vital to monitor patients who use any kind of cannabis product for symptoms of withdrawal.
When can a patient use marijuana after surgery?
Schick: It’s common for postoperative patients to ask when they can use marijuana again after surgery. I tell them if they are going to use marijuana, they should not take it until after anesthesia and any pain medication they were given after surgery have completely worn off. They should also not mix cannabis products with opioids or alcohol. Mixing causes decreased reflexes and increased sedation, it compromises memory and cognitive function more than if one substance is taken alone, and it can lead to addiction and use disorders.
Schick: We have to start the conversation and ask the questions of every patient. We can’t shy away from it.
Approach patients in a nonjudgmental manner, no matter what your personal beliefs are about marijuana. The way they are using it, how much, and when is what matters—not why.
Stress that their answers will remain confidential and that providing full information about their cannabis use will help the surgical team provide the best care and avoid complications. Make sure they are aware of the risk of complications and the consequences.
They need to understand the bottom line is that you, as the nurse, don’t want them to have complications. ✥