Clinical Corner

CANNABIS USE IS permitted in many states across the United States, while simultaneously being the most widely used illicit drug.¹ With the increased use of Cannabis for both recreational and therapeutic indications, the perianesthesia
nurse should be aware of how the drug works and the implications for patient assessment, monitoring, and health teaching. Screening for Cannabis use can help anticipate unpredictable responses to analgesics and other medications. In all phases of perianesthesia care, we can anticipate caring for patients who use cannabinoids more frequently. Keeping up to date with these trends empowers nurses with knowledge that helps us provide safe care and advocate for our patients.

 

Cannabis (marijuana) is one of the oldest documented medications in history and one of the most popular street drugs today.¹ Its history dates back to 2737 BC.² It is derived from the Cannabis plant and contains more than 500 chemical compounds.¹ Many of these compounds are cannabinoids, which interact with the receptors in the endocannabinoid system.² The main cannabinoids are cannabinol, cannabidiol, and delta-9-tetrahydrocannabinol (THC).¹ The compound

most associated with the psychoactive and euphoric effects of Cannabis is THC.² The varying levels of these three cannabinoids create different strains and potencies for the user.²

There is a growing patient population turning to cannabinoids as a treatment option or adjunct to manage medical issues. Although it is not recommended to treat acute pain, some common indications include chronic pain syndrome, neuropathic
pain, anorexia and cachexia, epilepsy, posttraumatic stress disorder, insomnia, headaches, inflammatory bowel disease, glaucoma, multiple sclerosis, and Parkinson’s disease.³ The list of therapeutic uses is anticipated to grow, reinforcing the
importance for nurses to be aware of misconceptions and stigmas that can be harmful to a therapeutic nurse-patient relationship.

 

Cannabis can have profound effects on the thermoregulatory processes. This is evident by the increased incidence and severity of shivering, secondary to perioperative hypothermia.4 It is postulated that regular users of Cannabis may have
greater postoperative hypothermia and shivering due to the antinociceptive effects of THC on the pathways involved with pain and temperature sensation.⁴ Although shivering may only be a minor annoyance for most patients, hypothermia can place increased physiological demands on the patient and lead to negative cardiovascular sequelae. Tachycardia, hypoxia, cardiac arrhythmias, and even myocardial infarct can be triggered in vulnerable patients.4 With knowledge of this
risk, the perianesthesia nurse can implement strategies in a proactive manner, such as use of a warming blanket during the Phase one recovery period.

 

In many states, Cannabis is a strictly illegal substance. It is not surprising that some patients are not forthcoming in sharing information about their usage. Even if they have a documented medical need forCannabis,patientsmaybe reluctant to share this with the anesthesia provider or perianesthesia nurse due to concerns of a negative stigma or perception by the health care team. In these cases, the standard question ‘‘do you use drugs for recreational or other use,’’ may receive a ‘‘no’’ in the check box. To encourage patients to be transparent, it may be helpful to outline the rational of inquiring about Cannabis use. We can reassure the patient that collecting this information helps ensure they are monitored for complications that can occur more frequently in Cannabis users, and that they receive the appropriate dosage of analgesic medications. Some potential concerns include a cross-tolerance to opioids, unpredictable response to medications, profound postoperative shivering and related increased metabolic demands, postextubation hypertension,
tachycardia, and upper airway distress.^1,5 Individuals who intake Cannabis by smoking the product (vs vaporizing or oral dosing) may also have a higher occurrence of stridor, airway distress, and postoperative laryngeal edema. This may be due to the presence of irritants found in Cannabis smoke, such as carbon monoxide.¹ Having an accurate understanding of the patient’s preoperative Cannabis use will help to optimize pain management and manage unexpected fluctuations
in vital signs related to pain, shivering, or airway irritation.

 

Although the patient may report benefits from routine use of Cannabis, immediate use of this product after a surgical procedure is not without risk. By being aware of the patient’s preoperative usage, the nurse can reinforce the risks of
combining Cannabis with prescribed pain medications. Common adverse effects that occur with Cannabis use are somnolence, dizziness, disorientation, and impairment of psychomotor skills, short-term memory, and judgment.6 These may lead to issues such as increased falls risk, oversedation, loss of recall of health teaching instructions, and accidents that cause harm to the patient or others (such as driving while impaired). One can see the serious risks of using Cannabis after discharge, particularly if combined with prescribed opioids. The physician may prescribe a reduced dose postoperatively, as appropriate for the patient, or put cannabinoids entirely on hold to achieve a balance of patient safety and comfort. For example, the patient who uses cannabinoids daily for fibromyalgia or a seizure disorder may have been instructed to reduce their Cannabis to a specific dose, versus the recreational user being advised to omit Cannabis use entirely until seen at a follow-up appointment with the physician. Overall, the understanding of the endocannabinoid
system and the physiological benefits of stimulating the cannabinoid receptors continue to be an area of interest, with need for further clinical studies.^1,3 Although it is a complex and controversial topic, we can support the safety of our patients by taking time to learn and have a working knowledge of the endocannabinoid system, its receptors and the implications of Cannabis therapy on perianesthesia care. This knowledge will help nurses to continue to act as
advocates for our patients.

Address correspondence to:

Heather Ead, Trillium Health
Partners, 100 The Queensway West, Mississauga, ON, Canada L5B1B8;

1. Beaulieu P. Anesthetic implications of recreational drug use. Can J Anaesth. 2017;64:1236-1264.
2. KhaiserM, PengM,AhrariS, PasetkaM,DeAngelisC.Medical cannabis dosing strategies in pain related conditions: A scoping review of current literature. J Pain Manage. 2016;9:449-463.
3. Katz I, Katz D, Shoenfeld Y. Clinical evidence for utilizing cannabinoids. Isr Med Assoc J. 2017;19:71-75.
4. Sankar-Maharaj S, Chen D, Hariharan S. Postoperative shivering among cannabis users at a public hospital in Trinidad,
West Indies. J Perianesth Nurs. 2018;33:37-44.

5. Beaulieu P, Boulanger A, Desroches J, Clark A. Medical cannabis: Considerations for the anesthesiologist and pain
physician. Can J Anaesth. 2016;63:608-624.
6. Turgeman I, Bar-Sela G. Cannabis use in palliative oncology: A review of the evidence for popular indications.
Isr Med Assoc J. 2017;19:85-89.

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