Blizzard
Want to know what poison is called the Silent Killer? Is colorless, odorless and tasteless i.e. completely undetectable? How car part theft might increase the toxicity of your car?
This is the Pick Your Poison podcast. I’m your host Dr. JP and I’m here to share my passion for poisons in this interactive show. Will our patient survive this podcast? It’s up to you and the choices you make. Our episode today is called Blizzard.
This is part of our holiday mini series, not Hallmark style, but toxicology style.
Want to know what poison is called the Silent Killer? Is colorless, odorless and tasteless i.e. completely undetectable? How car part theft might increase the toxicity of your car? Listen to find out!
Today's episode starts in the emergency department. You’re drinking hot chocolate with marshmallows and chatting. How is this possible? The emergency department is empty. Why? Because a massive winter storm is pummeling the hospital. You barely made it in, and you're not sure you’ll be able to get home, to a house with likely no power, meaning no electricity and no heat. For now, you're enjoying the warmth and camaraderie.
The hospital has power thanks to backup generators, but is operating at reduced capacity. The OR for example, isn’t open and the surgeons won't operate if at all possible. I don't know about you but I certainly wouldn't want to be on the table with my abdomen open if the generators fail. Unfortunately, these circumstances and difficult choices are faced by medical personnel around the world in under resourced areas and during wars and conflicts, but this hospital is in the US, so we’d hope to wait until power is back or the storm lets up to transfer the patient to another facility. The few patients you do have are here because they need electricity for their oxygen concentrators.
The ambulance doors bang open with a blast of frigid air. EMS arrives with three patients at once. Your colleague jumps up to take care of the sickest patient, a 50-year-old man in cardiac arrest, leaving you with the two other patients a 50-year-old woman and a 13-year-old girl, both unconscious.
Assisted by the nurses, you begin a quick assessment of the ABCs. The 13-year-old is protecting her airway and moving as the nurses place the IV. You turn your attention to the 50-year-old woman. She’s completely unresponsive, not protecting her airway. You intubate her and put her on a ventilator. Afterwards, her vital signs are as follows temperature 35.8 Fahrenheit 36.0 C. Heart rate 120 beats per minute, blood pressure 80/60. The ventilator is breathing for her so respiratory rate is good and oxygen saturation is 93% on 100% oxygen. You order IV fluids to treat the low blood pressure, as well as labs, an EKG and a chest x-ray. You’re happy to see the 13-year-old is now opening her eyes and moving spontaneously on the stretcher.
This is a good time to get more information from the medics. They report the three patients are family members, parents and a daughter, who they picked up from their house after the daughter called 911. They checked the blood sugars enroute, if you’re wondering, and all were normal.
There’s a lot more we need to do for these patients but let's talk first about the differential diagnosis to direct our work up and resuscitation efforts. Basically, we have three critically ill patients from the same house.
What potential exposures make a whole family sick? I know the ER doctors listening have jumped immediately to the correct conclusion. This is a classic scenario we’ve all seen. Let's run through some options for everyone else. Was the whole family poisoned by a nefarious neighbor or is this a murder suicide attempt? Possible but unlikely.
I’d be suspicious about a gas in this scenario. How about a knock-down gas like hydrogen sulfide which we’ve discussed before? No because the medics are fine. If it was hydrogen sulfide, they’d be dead too. It isn’t an organophosphate like VX or Novichok, they don’t have the killer Bs or other symptoms. Household detergents can mix, intentionally or unintentionally producing lethal chlorine gas. This usually poisons people in smaller spaces like a bathroom or a car, and again, the medics might’ve noted symptoms if they’d entered without respirators.
Question 1. Time to pick your poison. what is the most likely source of our patient's symptoms?
a. nitrogen poisoning
b. carbon dioxide poisoning
c. carbon monoxide poisoning
d. cyanide poisoning
The answer is A. this is a classic case of carbon monoxide poisoning. Nitrogen poisoning is what you get when you scuba dive and suffer the bends, nitrogen bubbles enter the joints and the brain. Carbon dioxide poisoning can be lethal and might look similar, however you need a source like dry ice, so no, not here. Cyanide poisoning is definitely lethal. It's doubtful that the 13-year-old girl would be improving so rapidly and also without the antidote.
Carbon monoxide is an extremely common poisoning. Most of us have a very low risk of ever developing, say arsenic toxicity, for example. Almost everyone is at risk of carbon monoxide exposure. More on this later.
Your colleague enters to help you out. Uh oh, that's not a good sign. You raise an eyebrow questioningly. He shakes his head. Silently telling you the dad did not survive the cardiac arrest.
Now that we think it’s carbon monoxide toxicity, can we test for it? Yes! For once a toxin that’s easy to test for. You order a co-oximeter. It’s a blood gas, either an arterial or venous specimen, is fine and send it to the lab. You’ll get the results in about 30 minutes.
You send it off. Question 2. While we wait, what's the treatment for carbon dioxide toxicity?
a. oxygen
b. naloxone
c. amyl nitrate
the answer is A. oxygen is the most important treatment. Naloxone is for opioids, and amyl nitrate is part of the cyanide antidote kit. We also use hyperbaric oxygen therapy, more on this in a bit.
Your colleague takes over for the 13-year-old girl, putting on an oxygen mask with 100% oxygen. Her chest x-ray and labs are unremarkable. Her mother’s x-ray and labs are mostly fine, except her troponin is elevated. This is the lab test related to the heart, leaking out if there’s damage. Wait a minute? Is this a heart attack? Did we make the wrong diagnosis? It is a heart attack, but we don’t have the wrong diagnosis. Carbon monoxide poisoning strains the heart.
The carbon monoxide levels come back. The daughter’s level is 50. Levels are reported as a %. 50% of her hemoglobin is carboxyhemoglobin. Meaning 50% of her hemoglobin is bound to carbon monoxide instead of oxygen. So that’s not good. The mother’s level is 66% and the expired father’s level is 80%.
These are very high. The levels are variable, different patients have different symptoms at different concentrations. Approximately, 80-90% is lethal. At around 20% patients can have headaches, at around 40%, loss of consciousness and confusion. Normal is <5%, unless you’re a smoker or a NYC bicycle messenger, then it’s 10%. Smokers are constantly exposed to CO from cigarettes, messengers inhale CO from bus and car exhausts in crowded urban areas.
These two patients need hyperbaric oxygen treatment. It’s done in a chamber where patients inside are exposed to oxygen under very high pressure. There are single chambers for one person, others are large multiplace chambers with space for several patients and a nurse. It’s not available at every hospital. Often patient’s have to be transferred. Who benefits? There is some room for debate, but generally accepted criteria include the following.
Any loss of consciousness even brief. Altered mental status, seizure or coma. Cardiac involvement, chest pain, EKG changes, ischemia, arrythmia. A CO level of 25 (some guidelines use 40). Or a level of 15 in a pregnant patient. Both of our patients meet the criteria for HBO therapy. Fortunately, your colleague has done a fellowship in HBO and the hospital has a chamber. Since it isn’t busy, he’ll dive the patients while you man the ED.
Let’s take a deep breath ourselves and step back to talk about carbon monoxide, where it comes from, and what it does. It’s a colorless, odorless, tasteless gas and is a byproduct of incomplete combustion of fossil fuels. Called the silent killer because it’s completely undetectable. Wait, what about the smell of gas from your stove, did you ask? That is an adulterant, added specifically to the gas to alert people to gas left on. It’s mercaptan, and it smells like rotten eggs.
In the US, and worldwide, carbon monoxide is a leading cause of poisoning morbidity and mortality. A very common cause in the US is faulty heaters, so not surprisingly many poisonings happen in fall and winter months. That said, there are many, many potential sources of exposure.
Question 3. running your car in the garage will likely result in severe carbon monoxide toxicity and death.
a. True
b. False
The answer is B this is actually false. It’s almost- almost- a historical fact at this point. People did commit suicide and die accidently from car exhaust fumes in an enclosed space, but modern cars with catalytic converters generally don’t release enough CO to cause mortality. In 1975 catalytic converters were introduced in response to the Clean Air Act. We can thank this legislation for the reduction in suicide due to CO poisoning, interestingly enough. But, some people have died as a side effect of the recent rash of catalytic converter thefts. I came across a case in the news of a couple who sold the catalytic converter from their Lexus to buy drugs and then inadvertently died while sitting inside the car. Tragic.
Boat exhausts, gas ovens, hookahs, fires, gas and charcoal grills, propane heaters, generators all produce carbon monoxide. Suba divers have been poisoned and died from CO contaminated oxygen tanks. Jacques Cousteau first reported this in 1946, after he and a group of divers experienced headaches, confusion, and weakness while diving underwater breathing from scuba tanks filled by a new diesel-powered compressor.
CO is found naturally underground. Question 4. Historically, what alerted miners to the presence of CO?
A. Pit ponies
B. Lamps
C. Canaries
Answer: C. canaries. This is where the saying canary in the coalmine comes from. Animals suffer effects of CO, like humans and ponies and mules will get sick. Canaries breathe up to sixty times a minute, which in addition to their small size, means they develops symptoms very quickly. An ill canary alerted miners to bad air so they could escape before it was too late. Some miners were so attached to their birds, they carried them in cages with tiny oxygen tanks attached, to revive the birds after exposure.
The medics are still hanging out in the nurses’ station enjoying some hot chocolate, since they haven’t gotten another call. They tell you the fire department checked the house after they removed the patients, measuring CO levels inside, finding CO at 800 ppm, which is very high. They also found a generator running INSIDE the garage.
The dad was killed in a terrible, and avoidable tragedy. Generators must be outside, no matter the weather, unless like in the hospital, they are specially ventilated. The generator running in the garage released CO, which built up in the closed house, killing the Dad. The very generators allowing us to provide medical care in the emergency department are the same responsible for the morbidity and mortality of our patients. Worsening weather, blizzards and hurricanes, has resulted in unnecessary deaths of many people from generators inside.
In the United States 50,000 patients a year present to emergency departments with CO poisoning and there are approximately 400 deaths per year. It’s impossible to estimate the incidence worldwide, but there are hundreds of thousands of reports of deaths per year.
What does CO do? It binds to hemoglobin. If it’s bound to hemoglobin, oxygen can’t bind. It has a higher affinely for hemoglobin then oxygen, binding 200-250 times more tightly. In patients with anemia, symptoms of carbon monoxide toxicity begin at lower levels. If you have fewer red blood cells, it's not surprising symptoms begin at lower carboxy hemoglobin levels. Ischemia, lack of oxygen is responsible for some of CO’s actions, but it’s also toxic to tissues and causes cell death via more direct mechanisms that are still under investigation. Symptoms do correlate with higher levels, but it varies from patient to patient. Patients with significant comorbidities, heart disease for example, can develop symptoms at lower levels.
Question 5. What classic physical exam finding is associated with carbon monoxide exposure?
a. cherry red skin
b. Brown blood
c. red urine
Answer is A. cherry red skin. It’s a classic boards question, though in truth it’s extremely rare and seen in only two to three percent of severe cases.
The list of symptoms caused by CO is massive. It includes neurological problems ranging from dizziness and headache, to loss of consciousness, seizure, coma and death. Cardiac manifestations range from mild chest pain to dysrhythmias to ischemia and cardiac arrest. This is just to name a few. It’s an astonishing span of symptoms. I don’t think any EM doctors had trouble with the diagnosis in our patients, as I mentioned earlier, but we all worry about missing CO in the ED. Why? Mild poisoning is more common and it’s very tricky, looking exactly like a mild cold or flu. Headache, dizziness, nausea and generally not feeling well. It’s very easy to miss.
Unlike the Dad, the vast majority of patients do survive, reflected in the statistics I said earlier. 50,000 ED visits in the US with only 400 deaths. That’s good news. The bad news is CO exposure is complicated by delayed sequela. Specifically delayed neurologic and neuropsychiatric problems. The problem is huge and difficult to quantify. An estimated 50% of patients with symptomatic poisonings develop delayed sequelae. Carboxyhemoglobin resolves with treatment with oxygen, usually in a few hours. The reason for HBO is not to get rid of carboxyhemoglobin, but rather to reduce the risk of developing delayed sequela and/or reduce the severity.
The list of problems is, again, massive. Extremity weakness and paralysis, urinary incontinence, peripheral neuropathy and blindness. Also, parkinsonism, dementia, amnesia, and psychosis. Onset can be delayed for weeks after exposure, and despite treatment may be permanent.
Treatment with hyperbaric oxygen works best if started within 6 hours, preventing many neurological sequelae. There is a benefit even if patients are treated later, certainly within 24 hours, benefits after longer delay are controversial.
Your colleague dives the mother and daughter in the HBO chamber. The mother wakes up but, but suffers severe neuropsychiatric sequela and permanent brain damage and paralysis. The daughter recovers medically, but faces a long road to recovery given her life will never be the same.
This case is fictional as are all our cases, but is based on real poisonings that occur frequently. What can you do to reduce your risk? Always, always keep a CO detector in your house and make sure the batteries work. I hate hearing the thing beeping or squawking about dead batteries in the middle of the night as much as you do, but CO detectors have saved my own family members from exposure. Never, ever use a generator inside, no matter what weather Mother Nature throws your way.
Last question in today's podcast. where else can you be exposed to carbon monoxide toxicity?
A. Soccer field
B. Baseball field
C. Amusement park
D. Ice rink
Follow the Twitter and Instagram feeds both @pickpoison1 and you’ll see the answer when I post it. Remember, never try anything on this podcast at home or anywhere else.
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While I’m a real doctor this podcast is fictional, meant for entertainment and educational purposes, not medical advice. If you have a medical problem, please see your primary care practitioner. Thank you. Until next time, take care and stay safe.