Smoking marijuana is extremely prevalent despite the fact that marijuana is considered a controlled substance. People who smoke cannabis have a tendency not to inform their physicians of their habit because of the illegality associated with the marijuana use. This may have serious ramifications when a habitual marijuana smoker under goes a procedure that requires anesthesia.
General Effects of Cannabinoids on Anesthesia
The interaction of anesthesia and cannabinoids is dose related and affects many of the different systems that anesthesia works on. The active ingredient in marijuana has been used for multiple medicinal purposes. Therefore, because of its medicinal attributes, it is a fact that it will interact with other medications. In the case of anesthesia, both compounds act on some of the same systems. This results in decreased or enhanced reactions depending on the severity of the drug usage.
CNS Effects of Anesthesia on Marijuana Smokers
People that smoke marijuana before anesthesia can expect problems related to ventilation and oxygenation. The inhaled cannabinoids act as CNS depressants which can in turn exaggerate the anesthetic effect depending on the amount of cannabinoids present in the persons system. Generally, there may be an increase in heart rate with low doses of marijuana and heart rates are markedly decreased with high doses.
Physiological Effects of Cannabis Affect Anesthesia
Red and swollen uvula and tonsils may also result from smoking marijuana. According to researchers (Mallet et al) a 17 year old boy who smoked some cannabis before surgery ended up with uvulitis (swollen and inflamed uvula) after a routine surgery. According to the research paper, his oxygen levels fell as his uvula blocked ability to breath. Luckily this reaction was reversible and the young man recovered from his ordeal. Had he informed his surgeons of his marijuana use prior to sugery, his surgeons could have possibly delayed his operation.
What Should Marijuana Users do when Anticipating Anesthesia
Anesthesia can be harmful and dangerous to marijuana smokers. This fact is based on the different systems that cannabinoids and anesthesia both affect. Even a small quick hit before a surgical procedure can have a negative effect. It should be noted that the severity of the effects are dependent on the marijuana habit of patient; either chronic or acute. Either way, cannabis users need to let their surgeons be aware of their usage patterns before anesthesia is administered. However, in the cases of an emergency surgical procedure where no prior information of marijuana use can be obtained, physicians are working on ways to better identify the subtle effects of chronic or recent marijuana use. If marijuana use is suspected, physicians may delay the surgery until the undesired effects are no longer a threat.
Marijuana smokers should remember that the cannabinoids in the smoke affect many different systems, importantly the central nervous system, respiratory system and the cardiovascular system. It is therefore important to make surgeons aware of prior cannabis use.
Sources
Mallat A. M, Roberson J, Brock-Utne J. G. “Preoperative marijuana inhalation-an airway concern.” Can J Anaesth 1996;43:691-3.
Robson, P. “Therapeutic aspects of cannabis and cannabinoids.” British Journal of Psychiatry, 2001;178, 107-115
