Page 30 - CASA Bulletin of Anesthesiology 2022; 9(5)

CASA Bulletin of Anesthesiology

In addition to the autonomic actions of cannabis use on the cardiovascular system, another
consideration is that THC is associated with endothelial dysfunction and oxidative stress, which
contributes to the increased risk of myocardial infarction in cannabis users . One study
7
demonstrated an almost five-fold increased risk within the first hour after smoking, which has
been demonstrated by additional studies, including a recent nationwide inpatient sample
illustrating that chronic cannabis consumption is associated with a meaningful increase in the
risk of postoperative myocardial infarction 20, 21 . Cannabis use has also been associated with
malignant arrhythmias, sudden-onset atrial fibrillation, coronary spasm, sudden death, cerebral
hypoperfusion, and stroke . Therefore, cumulative evidence suggests that a preoperative EKG
19
and echocardiogram may be valuable components to perioperative cardiovascular monitoring .
15
Respiratory effects
There is little evidence of respiratory system effects of cannabis when administered by routes
other than smoking or vaping, and the effects of cannabis consumption via these inhaled routes
are similar to those of tobacco smoking. Inhaled routes of cannabis administration facilitate the
entry of high concentrations of cannabinoids and non-cannabinoid chemicals into the airway and
lungs, which then quickly enter the bloodstream, like those associated with tobacco smoking.
These chemicals can act as bronchial irritants, like tobacco cigarette smoke, causing airway
hyperactivity, edema, obstruction, chronic cough, bronchitis, emphysema, and bronchospasm 11,
13, 15, 19. There is also concern that cannabis may be more irritating to the airways due to burning at
a higher temperature than tobacco 19, 22, 23 . Further, certain characteristics of cannabis smoking,
such as the technique and inspiratory effort previously mentioned, may result in greater
carboxyhemoglobin levels and tar retention in the airways . More specifically, prolonged or
24
deep inhalation, shorter butts, and higher combustion temperatures may result in these
respiratory effects that could complicate perioperative cares . Due to these parallels between
19
tobacco and cannabis smoking, perioperative providers may also consider an ASA classification
2 for current cannabis smokers.

In addition, the dangers of vaping is evident by the U.S. Food and Drug Administration
(FDA) warning about vaping THC oil, which was due to a multitude of reports of severe
pulmonary disease development, termed e-cigarette or vaping-use associated lung injury
(EVALI) . Inhalational exposure to these chemicals can result in extensive airspace
25
opacification seen as a centrilobular nodular pattern that resembles pneumonia and has been
described as a “tree-in-bloom” sign on imaging . Therefore, any patient presenting in the
26
perioperative period with new-onset respiratory disease and a history of vaping THC should be
evaluated with concern for EVALI and other potential respiratory issues .
13
Cannabis smoking has also been associated with postoperative airway obstruction, such as
pharyngeal and uvular edema 27-29 . Accordingly, it is recommended to postpone surgery when the
patient has smoked cannabis shortly before an elective surgery, which is congruent with the
recommendation to avoid elective surgery for at least 72 hours after cannabis use due to the
cardiovascular effects described above . Nevertheless, perioperative providers may consider the
19
administration of steroids in order to reduce the risk of airway obstruction due to edema or
inflammation, however it would be prudent to remain mindful of the increased risk for
myocardial infarction within one hour of cannabis use.

P a g e 29 | 66