CC
A 21-year-old male presents for extraction of four asymptomatic, impacted third molars with local anesthesia and intravenous (IV) sedation.
HPI
The patient is a male who uses electronic cigarettes but is otherwise healthy. Treatment was planned for extraction of all four asymptomatic, impacted third molars with IV sedation. The patient arrives with nothing by mouth status for more than 8 hours with an escort. He states he has refrained from vaping for the past 24 hours, as requested in his preoperative instructions.
PMHX/PDHX/medications/allergies/SH/FH
The patient’s past medical and surgical histories are noncontributory. He does not use any medications and denies any drug allergies. He states that he vapes throughout the day and often uses vaping products infused with delta-9-tetrahydrocannabinol (THC) and nicotine. He denies any other drug or alcohol use.
Note: Some patients who use e-cigarettes deny smoking unless asked specifically about vaping . It is important to inquire specifically and separately regarding the use of e-cigarettes and marijuana. Questions should be asked regarding the most recent use as well as the duration, route, and frequency of use. An in-depth discussion on the perioperative evaluation and management of patients who vape and use THC is included in the discussion section of this chapter.
Examination
General: Well-developed and well-nourished male in no apparent distress. (THC use can cause anxiety, paranoia, and psychosis.)
Weight: 80 kg.
Vital signs: Vital signs are normal, and the patient is afebrile. (Some of the most consistent effects of acute cannabis use are tachycardia and orthostatic hypotension.)
Maxillofacial: Normocephalic, atraumatic. No lymphadenopathy. Examination of the temporomandibular joint reveals no clicking, popping, or pain to palpation. The muscles of mastication are nontender to palpation. Cranial nerves are normal bilaterally.
Intraoral: The maxillary third molars are not visible intraorally. The mandibular third molars are partially visualized but without sufficient room for functional eruption. Bilateral mandibular second molars have probing depths greater than 4 mm on the distal. No swelling or signs of infection are seen.
Airway: Maximum interincisal opening 3+ fingerbreadths, Mallampati class I, thyromental distance 3+ fingerbreadths.
Cardiovascular: Heart has a regular rate and rhythm.
Pulmonary: Lungs are clear to auscultation bilaterally. (e-Cigarette and THC users may exhibit preoperative wheezing, which increases the risk of intraoperative bronchospasm.)
Note: It is essential to assess for signs and symptoms of acute marijuana use because many of the concerning anesthetic implications are related to acute effects. Furthermore, there is controversy regarding the appropriateness of obtaining informed consent from a patient with acute cannabis intoxication.
Imaging
Panoramic radiograph is the initial diagnostic study of choice. Additional imaging, including cone-beam computed tomography, may be ordered as indicated. In this particular case, the panoramic radiograph showed partial bony impaction of teeth #1, #16, #17, and #32 without any radiographic predictors of inferior alveolar nerve proximity or pathology associated with the teeth to be extracted. Further imaging was not indicated.
Labs
Routine labs are typically not indicated for healthy patients undergoing outpatient dentoalveolar surgery even for patients who smoke e-cigarettes or use THC.
If patients have been instructed to abstain from vaping preoperatively, urine or blood tests for cotinine (a metabolite of nicotine) can be ordered to verify patient compliance. Cotinine remains in the body longer than nicotine, so it is a more reliable test to detect and measure nicotine exposure. Cotinine levels remain detectable in urine and blood samples for up to 7 days. Cotinine test results are positive in patients using nicotine replacement therapy and smokeless tobacco as well as e-cigarettes or tobacco.
Similar toxicology screens exist for marijuana but can only provide qualitative data regarding the use of marijuana over the past 30 days. These tests are unreliable in confirming patient reports on timing of use because of nonlinear relationships between plasma cannabinoid levels and degree of intoxication.
Assessment
A 21-year-old male with heavy use of e-cigarettes, including products infused with THC and nicotine, presenting for extraction of four asymptomatic, impacted third molars with local anesthesia and IV sedation. The patient has followed preoperative instructions to refrain from vaping for 24 hours before the procedure.
Treatment
After standard monitors were applied, the patient was administered 4 L of oxygen via nasal cannula. Sedation was initiated using 2 mg of IV midazolam, 50 mcg of IV fentanyl, and 40 mg of IV propofol. During administration of local anesthesia, the patient began moaning and attempting to reach for the anesthetic syringe. An additional 2 mg of midazolam and 40 mg of propofol were given to deepen the sedation. Throughout the sedation, the patient remained in a lighter plane of anesthesia despite repeated boluses of propofol. After extraction of the last tooth, the patient began wheezing, and his oxygen saturation decreased from 100% to 85%. Capnography showed a slower upslope (shark-fin appearance).
The oropharynx was suctioned, all materials were removed from the mouth, and attempts to improve the airway were made by head tilt and jaw thrust. The patient’s condition continued to decline with a progressive decrease in oxygen saturation below 85% despite increased respiratory efforts by the patient. The diagnosis of bronchospasm was made. An attempt to mask ventilate with 100% oxygen revealed airway resistance, and four puffs of albuterol were given via the bag-valve-mask. Mask ventilation remained difficult, and the anesthetic plane was deepened with administration of 50 mg of IV ketamine.
The patient’s airway resistance slowly decreased with continued bag-mask ventilation. Oxygen saturation returned to 100%, and all other vital signs normalized. The patient was recovered and discharged to his escort after criteria were met without further complication.
Complications
The long-term complications of vaping are unknown because it is still a relatively new trend. In the short term, however, use of e-cigarettes has been shown to have significant effects on pulmonary status and wound healing. Specifically, e-cigarettes decrease airflow by increasing airway resistance, increase oxidative stress, impair lung development, increase mucin production, and depress host defenses.
The chronic effects of marijuana smoking are better understood and include cough, chronic bronchitis, and emphysema similar to those seen in chronic tobacco smokers. Acutely, the most consistent effects of cannabis are tachycardia and vasodilation, and there is evidence that this combination leads to an elevated risk of myocardial infarction (MI) caused by an increase in cardiac output, oxygen demand, and cardiac work. This risk of MI decreases 1 hour after use.
The complications associated with surgery under IV sedation in patients who chronically vape or use marijuana are related mostly to the increase in airway inflammation and reactivity, which places these patients at risk of perioperative respiratory airway events such as coughing, laryngospasm, bronchospasm, and hypoxemia.
Recent data also support the idea that cannabis users require significantly higher doses of propofol to induce and/or maintain anesthesia. A 2009 study on self-reported cannabis users showed that they required significantly higher induction doses of propofol to achieve loss of consciousness and a bispectral index below 60 compared with nonusers. A 2019 study found that cannabis users required 220% more propofol to complete endoscopic procedures than nonusers. In the example patient, normal doses of propofol resulted in a lighter sedation plane in a chronic marijuana user, which put this patient at increased risk of bronchospasm in an already reactive airway.
Acute cannabis intoxication can also cause anxiety, paranoia, and psychosis in some patients, which may result in a more violent or agitated anesthetic emergence.
Postoperatively, e-cigarettes and marijuana appear to have effects similar to other tobacco products related to wound healing. Both are associated with an increased risk of wound dehiscence and surgical site infections because of decreased immune defenses and the proinflammatory effects of the inhaled agents.
Other studies have also shown that cannabis users report higher pain scores, have worse sleep, and require more rescue analgesics postoperatively than nonusers.
Discussion
Vaping basics
Vaping is the inhalation of a vaporized liquid from a battery-operated device, disposable or refillable. These devices have many names: e-cigarette, vape pen, mod, tank, and so on. The device heats up the liquid, which contains (1) a carrier solvent, usually propylene glycol or glycerin; (2) various flavorings; and (3) the active drugs that become aerosolized upon heating, including nicotine, cannabinoids, or both.
The constituents of liquids and aerosols in e-cigarettes are essentially toxic and have a variety of degrees of carcinogenic, cardiac, pulmonary, immunologic, and vascular toxicity. The combined effects of many of these chemicals are unpredictable.
Although e-cigarettes can reduce exposure to many of the harmful toxins in conventional tobacco and cigarette smoke, they introduce a new array of potential toxins. Numerous toxic compounds have been identified in e-cigarette aerosols. With thousands of brands available and no set Food and Drug Administration standards, it can be difficult to determine the exact composition of a given e-liquid. Exposure risk certainly varies between the different manufacturers and flavors.
Marijuana basics
Marijuana is derived from plants of the genus Cannabis . The main psychoactive product of the plant is THC. Another common cannabinoid is cannabidiol, which lacks the psychoactive effects of THC. Many modern marijuana products have been created to maximize THC content and enhance the recreational effects. Our understanding regarding the physiologic changes of marijuana on humans is limited by the variable effects of different types and concentrations of cannabinoids as well as research limitations in the US because of its Schedule I status.
Vaping prevalence
A 2021 survey of high school students in America in the 2021 National Youth Tobacco Survey found that 11.3% had used e-cigarettes during the past 30 days with 43.6% of users using e-cigarettes on more than 20 of the past 30 days. Notably, 15.6% of high school users reported not knowing the e-cigarette brand they use. Among adults, the Centers for Disease Control and Prevention (CDC) estimates that in 2018, 3.2% of people older than 18 years of age were current e-cigarette users. Among Americans aged 18 to 24 years, 7.6% were current e-cigarette users as found in the 2018 National Health Interview Survey. A premise among e-cigarette users is that it is a safer form of nicotine than traditional smoking. It was also initially thought to be a mechanism for smoking cessation; however, data are lacking to support their efficacy in this regard. There is concern that the use of e-cigarettes, with higher nicotine concentrations than tobacco cigarettes, by youth may actually increase dependence and the subsequent frequency and intensity of smoking and vaping.
Marijuana prevalence
Marijuana is currently designated a Schedule I drug by the US Drug Enforcement Agency. This federal relegation is reserved for products without any accepted medical use and a high potential for abuse. However, 37 states currently allow medical marijuana use, and 17 of these states allow recreational use despite federal law. As a result, marijuana use is becoming more common in the general population. The CDC estimates 48.2 million people older than the age of 12 years, or about 18% of Americans, used marijuana at least once in 2019. In Americans ages 18 to 25 years, more than 35% used marijuana at least once according to the 2019 National Survey on Drug Use and Health. As these numbers increase, more patients who use marijuana products will be presenting for oral surgical procedures. Unfortunately, marijuana’s scheduling classification has also limited the ability of US-based researchers to study the effects of cannabis products.
Evaluating patients who use e-cigarettes or marijuana
In the preanesthetic evaluation of these patients, some specific questions to ask include:
- 1.
Do you use nicotine in your e-liquid? (Ninety-nine percent of the e-cigarettes sold in the United States do contain nicotine.)
- 2.
Do you use THC or other cannabis products in your e-liquid? (THC is less common than nicotine but is commonly used, especially in states where it is legal.)
- 3.
How much e-liquid or “vape juice” do you use in a typical day? (E-liquid comes in different nicotine concentrations and the pods or cartridges come in different volumes; therefore, quantifying the amount an individual vapes can be difficult. For reference, the nicotine in one 5% JUUL pod [a prevalent brand] is equivalent to about 1 pack of tobacco cigarettes.)
Users should be advised to pay attention to the nicotine content of their preferred e-liquid. Before anesthesia, it is also critical to ask about most recent use, especially as it relates to THC, because many of the most concerning anesthetic implications are related to its acute effects. See Table 17.1 for the perioperative considerations in patients using marijuana.
