Significant Role Of The Anesthesiologist For The Patient On Marijuana

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Marijuana refers to the dried leaves, flowers, stems, and seeds from the Cannabis sativa or Cannabis indica plant. The plant contains the mind-altering chemical THC and other similar compounds. Extracts can also be made from the cannabis plant. The most prevalent psychoactive substances in cannabis are cannabinoids, most notably THC. The psychoactive effects of cannabis, known as a “high”, are subjective and can vary based on the person and the method of use.

When THC enters the blood stream and reaches the brain, it binds to receptors. Some effects may include a general alteration of conscious perception, euphoria, feelings of well-being, relaxation or stress reduction, increased appreciation, including humor. Anxiety is the most commonly reported side effect of smoking marijuana.

Dr Rudram Muppuri
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Mrs.Sreerupa Patrnobish holds a conversation on the health implications of use of marijuana in relation to surgical preparation and anesthesia with Dr Rudram Muppuri.


Originally appreciated for its utility as fiber, later marijuana started use as a drug of abuse. Marijuana use dates back at least three thousand years before Christ to Chinese Emperor Shen Nung. After traveling half a world to the Middle East, it was brought to the West by the Spanish. While marijuana has been used by Americans recreationally for decades, it is a topic that is becoming increasingly important in our modern society. According to the National Institutes of Health (NIH), marijuana use in 2016 rose from 4.1% to 9.5% of the U.S. adult population. With more states in the USA eliminating the legal ramifications of its use and a growing debate about its federal legality, this is a subject that routinely makes local and national headlines. The use of marijuana in India is known for centuries. Given the commonality of its symptoms of use, we reached out to Dr. Rudram Muppuri, a US based non-resident Indian anesthesiologist affiliated with the McLaren Clinic in Flint, Michigan, who was one of the first to identify the cardiac and other risks of marijuana in preanesthetic evaluation and in surgery. In a reveling scientific abstract, Dr. Muppuri had pointed out that marijuana can cause heart-attack like symptoms. With a diverse nature of commercial products on the shelf from oral sprays to chocolate squares and aphrodisiacs, marijuana is no longer restricted to a rolled cigarette or chillum. Mrs.Sreerupa Patrnobish discussed the health implications of use of marijuana, especially in relation to surgical preparation and anesthesia, with Dr. Muppuri.

SP. The medical community has joined the debate in marijuana. Could you please elaborate the key issues Dr. Muppuri?

RM: The most obvious matter in hand between medicine and marijuana is medicinal marijuana. The effects of marijuana have been well documented, allowing the push for its use as medicine within multiple medical disciplines. Proponents of its use advocate its action on the endocannabinoid system. Studies show that it may be used as an analgesic, immunosuppressant, muscle relaxant, anti-inflammatory agent, appetite stimulant, antidepressant, antiemetic, bronchodilator, neuroleptic, antineoplastic and even as an antiallergen.

There is however, very little information, if any research evaluating use of marijuana in surgery and impact on anesthesia. This gap of information posits a problem. While many surgeons may obtain history about recreation drug use including marijuana, many other drugs have established evidence-based outcomes that allow variation in surgical planning as needed. However, when it comes to marijuana, surgeons have to make their own decisions. With a reported estimation of 10%–20% of patients between the ages of 18 and 25 years regularly using marijuana, it is highly important that we become cognizant of issues pertinent to the care of the patients on marijuana prior to surgery and provide special intra- and post-operative care (please also see below).

SP. How does marijuana enter the body system?

RM: When marijuana is smoked, tetrahydrocannabinol (THC) and other cannabinoids are absorbed rapidly through the lungs with effects peaking in 15 minutes. These effects can persist for up to a dose-dependent 4 hours in the acute setting. When ingested orally however, onset of effects is slower (15 minutes in contrast to 90 minutes) but has a longer duration of action (4 hours versus 5–6 hours), due to continued absorption in the gut. This is despite a lower bioavailability due to first-pass metabolism by the liver which results in a blood concentration 25% of what is obtained if smoked. The cognitive/psychomotor effects can be present for up to 24 hours regardless of administration route. Cannabinoids are highly lipid soluble, meaning that it can stay in the body system for very prolonged periods of time. This leads to a slow release into the bloodstream with a single dose not fully eliminated for up to 30 days. This has very important impact on surgical patients, as the drug tends to be retained in the body for long periods and can significantly alter the postoperative course.

SP. You have shown in your clinical study that marijuana can predispose to heart attack and poses special risk for anesthesia. Could you further elaborate heart side effects of marijuana?

RM: The cardiovascular effects of marijuana use range from benign to worrisome based on the timeline of use and dosage. Tachycardia or rapid heart rate may be induced beginning within the time of inhalation, and persisting at least 90 minutes, with the maximum heart rate reached at an average of 30 minutes. There can be a significant elevation in both the systolic and diastolic blood pressures as well as the presence of premature ventricular contractions (PVCs), which are serious heart rhythm disturbances, in subjects who received the higher doses. In addition to sinus tachycardia, marijuana use has been linked to multiple electrocardiogram (EKG) changes. In fact, Brugada-like features, which portends sudden cardiac death, can be seen. Marijuana use also has a role as a risk factor for myocardial infarction, as it is known to cause plaque rupture within the wall of the coronaries.

SP. Can marijuana cause stroke?

RM: Marijuana has also been reported as a risk factor for stroke, especially ischemic strokes. These are associated with either a recent increase, in the days leading up to the event, or chronic history of heavy marijuana use. When cohort studies were performed comparing marijuana users with resultant limb arteritis to patients suffering from thromboangiitis obliterans, marijuana associated arteritis occurred in younger, usually male patients with a unilateral, lower limb as the common presentation. This disease, also called Burger’s disease, is commonly seen in India, as smoking tobacco in different forms is the root cause and a common occurrence. In all ways, the chemical contents of marijuana hurt the wall of the blood vessels.

SP. Apart from marijuana, smoking tobacco poses risk during anesthesia. Can you distinguish the effects between the two?

RM: The commonest route of marijuana administration is inhalation via smoking. Due to the unfiltered nature of the marijuana cigarette compared to commercially available tobacco cigarettes, the amount of carcinogens and irritants, like tar, that gain entry to the upper airway is increased, with approximately a three-fold increase in tar inhalation and one third more tar deposition in the respiratory tract. More specifically, the tar from the cannabis smoke contains greater concentration of benzanthracenes and benzopyrenes (each a carcinogen) than tobacco smoke. In addition, as compared to smoking tobacco, there is a two-thirds greater puff volume, one-third greater depth of inhalation and a four-fold longer breath-holding time, all of which are common smoking behavior to try to enhance and maximize absorption of the active components, which is around 50% of cigarette content. These practices result in five times the amount of carboxyhemoglobin levels as compared to the typical tobacco smoker. The pulmonary complications in the chronic marijuana smoker are equivalent to those seen in the chronic tobacco smoker. In fact, 3–4 cannabis cigarettes daily is the same as 20 tobacco cigarettes in terms of lung and airway tissue injury.

SP. What are the questions you ask to rule out risk from marijuana use and abuse prior to surgery?

RM: The rate of marijuana use via patient self-reporting is only scant at 14% amongst surgical patients. Illicit drug use is a routine part of my preanesthetic assessment, especially in patients that I find with behavioral problems including whom I find hard to settle, due to anxiety or other psychologic manifestations.

SP. What are the anesthetic risks in individuals who have used marijuana and undergoing surgery?

RM: There are significant drug interactions between active components of marijuana and commonly used anesthetic medications. There is cross-tolerance between marijuana and several anesthetic drugs including barbiturates, opioids, prostaglandins, chlorpromazine and alcohol. As a result of fat solubility and slow elimination from the tissues, cannabinoids may be present to interact with multiple anesthetic agents. Multiple boluses of propofol and midazolam are required to achieve appropriate sedation. Significantly increased doses of propofol needs to be administered to facilitate successful insertion of the laryngeal mask and thus suggesting that the increased doses in chronic marijuana users may be a requirement for appropriate loss of consciousness as well as jaw relaxation and airway reflex depression. The synergistic effects of cannabis include significant impact on the autonomic nervous system and its pharmacology. This system maintains the cardiocirculatory integrity. These include potentiation of nondepolarizing muscle relaxants, potentiation of norepinephrine, the augmentation of any drug causing respiratory or cardiac depression, as well as a more profound response to inhaled anesthetics sensitization of the myocardium to catecholamines due to the increased level of epinephrine. All of these cumulatively can lead to fatal cardiovascular outcomes. Due to these potential autonomic reactions, as well as psychiatric complications, such as withdrawal effects and their interference with anesthetic induction or postoperative recovery, it is imperative to inquire about drug history or avoiding elective operations altogether. Not only should an extensive history of drug use be elicited at the time of the preoperative assessment, including the frequency of use and the time of last use, but that anesthesia should preferably be avoided in any patient with cannabis use within the last three days.

SP. Is the need for postsurgical pain medications reduced in individuals who habitually use marijuana?

RM: With advancement of surgical techniques, more complicated and potentially painful procedures are becoming common. Over 80% experience postoperative pain that was rated as either moderate or severe. This pain can set off a series of changes that may harm various systems ranging from cardiovascular to the central nervous system and has been shown to lengthen hospital stays and time to first ambulation, cause significant barriers in postoperative nursing and physiotherapy, increase healthcare costs, and reduce the patient’s satisfaction with the surgical outcome. However, appropriate and adequate postoperative analgesia improves recovery, including improving cardiac function and decreasing mortality and morbidity related to pulmonary function, decreases risk of blood clots, diminishes the possibility of chronic pain syndrome, and improves overall outcome. Appropriate pain control is also at the root of starting another long-term opioid abuser. Marijuana plays a role now in medicine as an analgesic and is being increasingly legalized across the different states in the USA. Prescribed for a number of diagnoses, medical marijuana has been shown to be both effective and safe in the treatment of chronic pain and has gained popularity as a medication for neuropathic pain. Marijuana may play a more important role in pain management when combined with opioids. However, the appropriate management of marijuana users with opioids postoperatively is more complicated and is not a linear interaction effect. In chronic marijuana users, the perioperative narcotic requirements to gain appropriate analgesia are enhanced to a great degree. Yet despite this increase, intriguingly, patients are more likely to subjectively experience less pain than those of their non-marijuana using counterparts. Clinically, this increase materialized in the form of a narcotic requirement twice that of the average patient of the same height and weight each day over the course of two postoperative days, demonstrating a combined drug effect between marijuana and opioids, which must be in the view of the anesthesiologists when considering the potential postoperative complications that may arise from the increased doses of opioids.

SP. Is there any contraindication for bariatric surgery in individuals who have used marijuana?

RM: Whether marijuana use should be a contraindication to bariatric surgery is a debatable topic. Due to the many effects marijuana has on the cardiovascular, pulmonary, immunologic, and central nervous system, cannabis use worsens and produces adverse outcomes in the postoperative period. These potential risks and lack of screening resulted in the recommendation that practitioners of bariatric surgery should be devoted to assessing controlled and problematic levels of preoperative substance use and take the time to discuss the potential postoperative risks with patients. As I and others have shown, pain management is an important aspect in bariatric surgery, especially for postoperative recoveries. But it should be done under expert medical supervision. Many societies do not currently favor bariatric surgery if someone is on marijuana.

SP. Any final comments Dr. Muppuri?

RM: The documented evidence of the effects of marijuana is of great concern for surgery. Whether it be the presentation of arrhythmias, myocardial infarction, stroke, pulmonary obstruction as well as anesthetic concerns and/or thromboembolus or bleeding, marijuana’s multi-system, multi-organ effects are possible confounders to a variety of medical outcomes, including surgical events. With cannabinoids being shown to be present for up to 30 days within the fat, its potential to affect the entire operative course in either chronic or acute smokers must be thoroughly evaluated.