Critical Care Toxicology: What Did My Patient Take? 1/2

Surprisingly, patients aren’t entirely truthful about what they may have ingested to make them sick. Or, they might be in a state where they can’t share the information due to their medical condition. This can put the medical team in a worse case scenario where if they knew what the patient took . . . they might be able to offer the right antidote.

Without the information it can seem like a shot in the dark to try and reverse the effect the substance is having on the individual.

Recently, I heard a fascinating lecture given by a doctor of toxicology who gave some guidelines, based on the patient’s signs, as to what that drug might be and I thought I’d share them with you for some great writing details.

Let’s first assume that we at least know the patient likely ingested something. They’re discovered by EMS in their home with an array of alcohol, pills, and drug paraphernalia. A good EMS team will try and take stock of what they see and report to the ER what they found. They’ll likely not grab illegal drugs like weed or powders (this would be for the police to confiscate) but they may bring unidentified pills and prescription bottles to help us. This can help narrow down what the person might have taken.

The opposite is finding someone unconscious in the middle of the street with nothing around them and the police call EMS for transport.

Or, even better, a teen has been involved in a “pharming party” where they raid every medicine cabinet they have access to and dump all they find into a punch bowl. Then proceed to swallow a handful of these pills with a bunch of alcohol. I have had cases like this where EMS grabbed the bowl and brought it with them. I mean, a punch bowl filled with prescription drugs but no boxes or labels. Even if we have the pills– it takes time to identify what they might be.

Time the patient might not have.

Scenario #1:

The patient presents with low heart rate and low blood pressure.

First, why would we think this may be a drug ingestion? The body’s normal response to low blood pressure is to increase your heart rate– not lower it– as a mechanism to prevent shock.

There’s only one other medical state I can think of that would mimic this and that would be a spinal cord injury. When the spinal cord is damaged, you lose nerve innervation that would help increase blood pressure. So, in absence of a traumatic event, a spinal cord injury would be ruled out. However, an unconscious person can’t tell us if they’ve been injured which further complicates the picture.

Drugs that can create this picture could be the following:

1. Beta-blocker. Your heart has beta receptors. When these are stimulated, say by a release of adrenaline in your body, the heart contracts harder and beats faster. A beta-blocker “blocks” these receptors so the opposite happens. Propranolol is beta blocker.

2. Clonidine. Clonidine is a sympatholytic medication meaning it blocks the flight or fight response. It’s used to treat high blood pressure but also ADHD and anxiety disorders. Personally, I’ve seen quite a few of these ingestions and they tend to be very unpredictable. The child can be fine one minute and then, with little warning, have a very slow heart rate and be unarouseable.

3. Baclofen: A muscle relaxer.

4. Calcium Channel Blocker. These drugs do what they say– block the flow of calcium from entering heart cells and those that line your blood vessels. Calcium acts to contract things so blocking its flow has the opposite effect. They are used to treat high blood pressure, migraine headaches and Raynaud’s disease. Verapamil would be a drug in this class.

5. Digoxin: I talk extensively about digoxin toxicity in this post.

How do we treat? With the exception of digoxin, there is no specific antidote so it is largely symptomatic support.

1. Give IV fluids. This will help support and raise the blood pressure.

2. Give Calcium. This helps things contract– thereby raising the blood pressure as well.

3. Give a Vasopressor. Vasopressors work to contract blood vessels to raise blood pressure. These would be drugs like dopamine and epinephrine (adrenaline).

There are a few other things to be done but this will give you plenty to write a scene that involves this type of drug ingestion.

Have you written a medical scene that dealt with a drug overdose in your novel?

Acetaminophen Poisoning

Acetaminophen, commonly known as Tylenol, is one of the number one ingestion (accidental and intentional) calls to the Rocky Mountain Poison Control Center. One of the reasons behind this is that Colorado has one of the highest rates of prescription drug abuse and acetaminophen is a common co-ingredient of narcotics (Vicodin, Percocet and others.)

Using a possible overdose in a novel is a good way to increase conflict/tension. Acetaminophen ingestion, if caught early enough, is highly treatable with a mortality rate of <0.5% which is in large part to N-Acetylcystein (NAC).

Acetaminophen was first used in 1955. It’s primary function is as a pain reliever and fever reducer. It peaks in 45 minutes and the half-life is 2-3 hours. I discussed the importance of half-life and ingestions here.

Acetaminophen is metabolized by the liver which also becomes the primary victim in overdose. If untreated, acetaminophen kills off liver cells over the period of a couple of days. This type of overdose is the #1 cause of liver failure in the US, UK and Europe– again, largely as a result of prescription drug use/addiction.

What’s considered a toxic dose? Greater than 150mg/kg for a child and 7.5 grams and over for an adult. Keep in mind, extra strength tablets are 500mg each so taking just fifteen of these places a person in the toxic category. For an acute overdose, the entire amount needs to be ingested in eight hours. A person can still become toxic from chronic ingestions but it does complicate their medical management a little.

We do use decontamination at times in poisonings but the treatment for acetaminophen ingestion is so good that it generally outweighs the benefit of decontamination which is discussed here.

What’s most important in acetaminophen overdose is the four hour drug level (four hours after the time of ingestion.) Whether or not to give the antidote is based on this level. Now, in a massive overdose (let’s say twice the toxic level) the medical team may be directed to decontaminate the patient because the patient can die from a massive overdose even though their liver may be fine. At the four hour mark if the drug level is less than 150– the patient does not require NAC. If over 150– they get the treatment.

NAC can be given two ways– either IV or by mouth and should be started within eight hours of ingestion. The oral route is preferred because it goes to the liver in higher amounts. NAC works by enhancing a protein that breaks down acetaminophen in the liver when it’s own mechanisms are overwhelmed by the amount of drug the patient has taken.

Even if a patient denies taking acetaminophen, we’ll generally test for it under suspicious circumstances– such as admitting to taking another drug or suicide attempt through other means. In 8.4% of cases, the patient will test positive and 2.2% of those require extensive treatment.

A negative acetaminophen level doesn’t mean they didn’t take an overdose so in a patient where there is concern for acetaminophen toxicity– we would also draw liver enzymes. If those are elevated, the patient will get the antidote even if the acetaminophen level is negative.

Patients generally die from cerebral edema or overwhelming sepsis. Researchers are unsure why the cerebral edema develops. Sepsis occurs because the liver protects the body against bacteria and if the liver has died– their protective mechanism fails.

What’s interesting in acetaminophen overdose is there is little intermediate ground. Either the patient gets better or they don’t. Past a certain point, the only way to save them is to transplant their liver.

General Treatment of Ingested Drugs

One thing that has evolved a lot in medicine is the general treatment of drug overdoses. 

Early in my nursing career, I worked in a community ER. In this setting we saw both adult and pediatric patients. One day, three young boys were brought in after they’d gotten into grandma’s medicine cabinet and sampled a multitude of pills. 

In those days, if the ingestion was within one hour, we did use Syrup of Ipecac to induce vomiting and each of these boys got a dose and a big bucket. Syrup of Ipecac is more effective the more water you drink. All three children were lined up next to one another, each on their own gurney, and I walked down the line encouraging each of them of drink. 
Soon enough, one of them began to vomit. One of the other boys proclaimed that wasn’t going to happen to him and I simply gave him another glass of water to drink. After he saw his second sibling throw up, he said to me, “I don’t want any more water.” 
That didn’t keep him from the invetible. 
What we learned is that causing patient’s to throw up increased their risk of more serious complications– like aspiration pneumonia. It is a risk that while vomiting, you’ll inhale some of that material. 
Then there was “stomach pumping.” There’s a lot of confusion about what this actually is and the last time I did it was over twenty years ago. A large (literally garden size hose) is inserted down the patient’s mouth into their stomach and then, through a pumping action, the stomach contents are washed out with large amounts of saline.
The problem with this therapy became the electrolyte shifts that can happen when replacing stomach contents with saline and this practice has been largely abandoned as well. Also, having a large tube put down into your stomach also increases your risk for vomiting and the same risk discussed above still applies.

What has remained is the use of activated charcoal. Activated charcoal literally looks like ground up charcoal. It is a thick, sludge like material that is sweetened to make is more palatable. In kids– we usually put it in a covered up Styrofoam cup so they can’t see it. If they won’t initially drink it we may flavor it with chocolate milk. The problem becomes that whatever it is diluted in they have to drink all of in order to get the full dose.

Activated charcoal works by binding the drug to make it inactive. If the effects of the drug would be more detrimental to the patient (versus just observing and offering symptomatic support) then we’ll generally try to give it if the patient comes in within one hour of the overdose.

With any ingestions, we usually follow the direction of our Poison Control Center.

If your child has ingested anything of concern, I highly recommend you call them first at 1-800-222-1222.  

Principles of Poisoning: Part 3/3

Today’s post will conclude my three part series on Principles of Poisonings. There’s lots more to talk about in this area so I’m sure I’ll have more on this fascinating topic in the future.

For the last part, I’m going to cover basic treatment guidelines of the poisoned patient. We’re going to assume the patient arrives to the ED alert and breathing.

1. Obtain the patient’s weight. This may seems odd but when we look at whether or not a patient has ingested a toxic amount of the drug it will be determined by the mg/kg of the medicine. For example, if I take 1000mg of acetaminophen, this is a “normal” dose for someone of my weight. And no, I’m not going to tell you my weight. Let’s say, a child weighing 10kg took the same amount. This would be 100mg/kg of drug/body weight ratio. A normal dosing guideline for acetaminophen is 10-15mg/kg so this patient is at 10 times the normal dose.

2. Determine the amount of the drug and the time of ingestion. This can be more challenging than it seems. People don’t usually know the “exact” amount left in a bottle unless it is a medication they take every day. Also, kids are classic for not really being able to say how much they ingested. We assume worst case scenario and go from that point.

3. Call Poison Control. They are the experts. We go over the above information and generally follow their advice. Most often it will be observation and symptomatic support. Remember, patients will also have effects from the drugs we give as well. We want to minimize this if possible and only use these if the patient has an inherent risk of suffering toxic effects that are life threatening. Generally, if the patient presents within one hour of their ingestion to the ED and we are concerned they will have toxic effects, we will give activated charcoal. Syrup of Ipecac is generally out of vogue and no longer used. Then, we’ll obtain a baseline drug level (if it can be measured) and subsequent levels to make sure it is dropping.

Have you experienced a real life overdose/accidental ingestion?