March 15, 2022

Marijuana before Surgery and Anesthesia: What You Need to Know

What happens to your body if you use marijuana before surgery? Learn how to prevent dangerous side effects from cannabis during your surgery.

So my patient coming in for hip replacement is squirming around a little and looks uneasy. I’m thinking this isn’t just normal surgical anxiety, which is totally real, and has totally real effects on your body under anesthesia. No, this patient had something in their system, and I had to do some detective work before it came out that they were smoking weed to chill out in the parking lot before surgery.

I love plant medicine, but weed isn’t an ordinary plant. Marijuana affects your body in ways that are exposed under anesthesia. It can impact your pain, nausea, emotions, and sleep, and more. Let’s talk about what happens to your body with weed when you’re under anesthesia.

The influence of marijuana is revealed under anesthesia

I love plants, but cannabis is a little different

I love plants as medicine because they can be effective, gentle, and have fewer side effects than pharmaceuticals. But modern-day marijuana is different than other botanicals. To understand why, you need to know the basics about the cannabinoid system.

The chemical compounds of interest in weed are called Cannabinoids. There are three types of cannabinoids:

  1. Endogenous, meaning produced by your body
  2. Phyto, meaning they come from plants, like CBD and THC
  3. Synthetic, like medications (dronabinole, nabiximols, nabilone, epidiolex), or drugs of abuse (K2 or spice)

Modern marijuana is not like other botanicals I typically use. Here's what makes cannabis different:

  • Phytocannabinoid concentrations have been highly manipulated over the past 30 years. THC concentrations are naturally in the 1-3% range but now can vary up to 30%. Butane hash oil (or BHO) can concentrate THC into the 90% range.
  • The effects of cannabis depend on how it gets in your body. The most common ways are smoking and eating marijuana. Smoking marijuana kicks in much faster and wears off much faster compared to eating it. Eating marijuana takes longer to reach your brain and also stays in your body longer.
  • Weed is highly lipid soluble. This allows it to stay in the body for up to 30 days. The more you use it, the longer it lasts in your body. That means marijuana lasts longer in your body if you use it daily.
  • It's hard to study weed. Legal reasons aside, marijuana affects different mammals differently. For example, marijuana relaxes your body and raises your heart rate. Dogs, cats, and rats can have opposite effects though, depending on the organ system. For example, cannabis doesn't affect the breathing rate of your human body, but it can affect the breathing of cats and dogs. This makes it difficult to study weed and extrapolate back to humans.
Marijuana is a powerful plant that has been highly manipulated over decades. The effects of these new strains can affect your body in ways that are unexpected, and serious, in the operating room,
Marijuana may have some benefits in some patients... It also has high risk in the operating room

Possible Benefits of Marijuana:

Marijuana has been used for thousands of years in its natural form. What benefits does marijuana have in the body? Your body has receptors to cannabinoids all throughout your brain and spinal cord, and that’s where a lot of the activity takes place. Most of these benefits are still controversial because there’s so much variability in marijuana studies. Here are some key points:

  • It's difficult to standardize doses. We quantify cigarette smoking with "pack years." But we don't have an equivalent "blunt years" for smoking weed.
  • Different cannabis strains can have wildly different phytocannabinoid concentrations (ie THC and CBD)
  • Eating cannabis versus inhaling cannabis has different effects in the body

Marijuana for Chronic Pain

Cannabis has been studied for chronic pain, especially in patients with cancer.

It likely does help some patients, but the effects are typically modest. This may be attractive because the addiction potential of weed appears less than that of opioids, but cannabis abuse disorder is very real. The risks of respiratory depression (ie stopping breathing) are less than opioids, but potent cannabis strains may be tainted with opioids (like fentanyl) and this can be dangerous. Remember, when you stop breathing, you heart and brain can't get oxygen, and this can lead to heart attacks, strokes, and other organ damage.

Weed can help some patients with chronic pain. It may be safer in some patients as compared to opioids. However, the risks of marijuana, especially in the operating room, are very real.
Cannabis may help some patients with chronic pain. It may also worsen pain in some cases.

Weed for Seizures

This has been best studied in some rare forms of epilepsy in kids. There's actually a medication inspired by marijuana: epidiolex (cannabidiol).

Nausea and Cannabis

This one is very tricky. Some patients may have improvement of nausea. This has been studied in patients with cancer (from chemotherapy, for example) with mixed recommendations. However, some patients can actually have intractable vomiting. I've personally seen this multiple times in the emergency room!

Muscle pain and Marijuana

Spasticity in patients with multiple sclerosis may benefit from marijuana. Sativex is a synthetic cannabinoid approved for this use in some countries, but not recommended in others.

Cannabis for Sleep and Insomnia

Marijuana may help relieve anxiety and help with sleep, but results are inconsistent and modest at best.

Weed Munchies and Appetite Stimulation

Cannabis can increase appetite (while also relieving nausea in some patients). Some synthetic cannabinoids don't appear particularly effective. Maybe patients with cachexia should stick with phytocannabinoids.

Cannabis is a powerful plant that is highly lipophilic that is able to cross the blood brain barrier. This gives it powerful effects on your mood and anxiety. However, this can also affect your emotions, pain, sleep, and medication dosing requirements.
Marijuana affects your brain. Crossing the blood-brain barrier gives it relaxing effects, but it has more than just calming effects on your brain and body.

Marijuana Absolutely Affects Your Brain, Especially in Surgery

With these possible benefits in mind, recognize that cannabis crosses your blood-brain barrier and has significant impacts on your brain. The influence of marijuana is revealed under anesthesia.

Cannabis Increases Anesthesia Requirements

Marijuana uses increases your anesthesia requirements. Higher anesthetic dose requirements may increase the risk of you being aware under anesthesia. This is because you need more anesthesia to keep you asleep, and you may be at risk of being underdosed.

Weed and Delirium After Surgery

Marijuana, especially at higher THC concentrations, may increase the risk of paranoia and psychosis. Paired with anesthesia, these may increase the risk of waking up with delirium, like more emotional or even aggressive.

Marijuana and Insomnia

Marijuana may help insomnia in some patients. However, anesthesia disrupts normal REM sleep. Pairing cannabis with anesthesia may have the opposite effect and worsen sleep quality after surgery.

Withdrawals from Marijuana

Withdrawal from any substance or medication happens when your body no longer sees the chemical it was regularly seeing before. The symptoms of withdrawals are usually the opposite of what the chemical ordinarily does.

For example, if marijuana reduces anxiety, improves sleep, and reduces pain, withdrawals symptoms would be the opposite. Even if not life threatening, it can still be incredibly uncomfortable.

Withdrawals are more common after surgery because most patients aren't using the substances they normally use. This leads to worsening anxiety, anger, irritability, insomnia, depressed mood, cramping, and more. These are all already bad after surgery and anesthesia.

These withdrawal symptoms also overlap with other serious medical conditions, like malignant hyperthermia, serotonin syndrome, neuroleptic malignant syndrome, and thyrotoxicosis. This could make it harder to diagnose and treat complications if they occur.

Cannabis and Worsening Pain

While marijuana may help some chronic pain conditions, it may actually increase acute, post-surgical pain. This may be from the withdrawal effect.

Other Dangers of Marijuana in the Operating Room

Marijuana can have potent effects across your body. It affects your brain, heart, lungs, and even blood. It's important to hold off on marijuana for two weeks before surgery. Learn from Dr. Kaveh about how to safely prepare for surgery with safe anxiety treatments.
Cannabis can have wide reaching effects in your body while under anesthesia and while recovering from surgery

Cannabis Also Affects the Rest of Your Body

Marijuana affects cannabinoid receptors all across your body. Here are the major organ systems that get affected when you're asleep under anesthesia.

  • Heart: marijuana increases your heart rate. Under anesthesia, this can interact with our medications to increase the risk of heart attacks.
  • Lungs: cannabis burns at higher temperatures than tobacco. That can increase the risk of burns and swelling in your mouth and airways. This can be lethal under anesthesia. There's also a increase risk of asthma-like reactions (even if you don't have asthma).
  • Blood: smoking weed increases your blood's carboxyhemoglobin. This is one of the toxins that kills firefighters and your body is even more susceptible to death under anesthesia.
  • Emotions: cannabis use can cause worse anxiety, paranoia, and even psychosis after surgery. We believe this is more likely with higher THC doses. Remember that anesthesia itself can cause this, so marijuana appears to increase the risk further.
  • Nausea: anesthesia and surgery can cause nausea, but marijuana may independently increase the risk of nausea further.
  • Bleeding: synthetic cannabinoids may increase your risk of bleeding. In surgery, this can be life threatening! Bleeding out can be a real concern in the operating room.
It's important to hold off on marijuana for at least two weeks before surgery

Marijuana isn't the Answer... But What Should you do to Calm Anxiety Before Surgery and Anesthesia?

So marijuana definitely isn’t the answer to calm anxiety and chill out before surgery. It's important to hold off on marijuana for at least two weeks before surgery. But where does that leave you? Fortunately, there are loads of natural therapies to reduce anxiety that are very safe before surgery and anesthesia. Check out my videos on these techniques that use safe botanicals and mind-body therapies. Things like melatonin, breathwork, acupuncture, essential oils, and much more (see my other article)!

And best of all, once you learn these techniques, you’ll find that you can have incredible power over your health to hopefully need fewer, if any, medications.

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