- The administration of THC produces an increase in heart rate and conjunctival congestion followed by euphoria, drowsiness, short term memory and concentration impairment, and reduced cognitive ability.
- There can also be a dose-dependent increase in heart rate and systolic blood pressure in naive cannabis users.
- Increased heart rate, left ventricular contractility, and cardiac output have also been reported in experienced users after heavy daily consumption of marijuana.
- Both the recreational and medical use of marijuana has been associated with severe cardiovascular disorders.
- High liposolubility of cannabinoids results in accumulation in fatty tissues, which in turn delays elimination and increases the risk of drug interaction up to 5 days after exposure. This can cause sustained tachycardia in patients receiving general anaesthesia within 72 hours after cannabis exposure.
- Ischaemic stroke is also a common vascular side effect reported in cannabis users. Studies report a 2.3 to 2.9 fold incidence of cerebrovascular ischaemia in young cannabis users compared to tobacco smokers.
- Preoperative cannabis smoking is associated with postoperative airway obstruction. It is thus recommended that elective surgery should be postponed if the patient has smoked marijuana shortly before it.
- Alveolar haemorrhage and bronchiolitis are also associated with a high dose of THC as is pulmonary embolism.
- Cannabis exposure is linked to decreased body temperature. Hypothermia and shivering are frequently observed in cannabis users during the perioperative period. Increased heart rate, hypoxaemia, oxygen consumption, oxygen delivery, myocardial ischaemia, and acidosis are common physiologic effects of shivering.
- Cannabinoids have both pro-coagulation and anticoagulation effects.
- THC prolongs the action of some intravenous anaesthetics such as pentobarbital, thiopental, ketamine, propanidid and alfaxalone/alfadolone. Dose-dependent effects of THC have also been observed with the use of propofol, sevoflurane, and isoflurane.
- Concomitant use of cannabinoids and opioids can exacerbate acute pain and increase the incidence of opioid misuse.
- Some experts believe that cannabis can potentiate or prolong the effects of neuromuscular blockers.
Perioperative Management of Chronic Cannabis Users

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Published on : Wed, 26 Jun 2019