Sublimation

Mystery lovers, this one is for you. We are going to discuss a real-life scenario where a person can be found dead in an enclosed space, without evidence of trauma, intrusion, or even another person. 

Listen to find out how it happens!

Transcript

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 Sublimation. 

Mystery writers and mystery lovers, this one is for you. We are going to discuss a real-life scenario where a person can be found dead in an enclosed space, without evidence of trauma, intrusion, or even another person. Listen to find out how it happens!

Today's episode starts in your car. You’re on the way into a shift and already late. Worse the traffic is building up, blocked by a slow driver ahead. The slow car suddenly swerves erratically across three lanes of traffic, miraculously missing everyone else. It rolls into the grass, finally stopping when it hits a shallow ditch. Several people pull over to check on the occupants of the erratic vehicle. The traffic crawls past. You debate if you should stop, but you’re already late and the slow-moving car didn’t actually hit anything. You decide the medics can deal with this one. 

Your car inches ahead, finally pulling abreast of the scene. Two bystanders are pulling the driver out of the car. You take one glance and swerve off onto the shoulder. The glance is enough to see the driver looks dead. The bystanders are trying to help, but they haven’t checked her pulse and are definitely not doing CPR. 

You're wearing scrubs, so the bystanders automatically move away from the driver with a relived look on their faces. You put your fingers on the woman’s neck, confirming she doesn't have a pulse and start CPR. As you compress her chest, the song “Stayin’ Alive” starts to play in your head. Just like they taught you in every ACLS class to ensure the right rhythm of 100 compressions per minute. The incongruous absurdity of the song in this situation never fades. You confirm someone called 911 and EMS is on the way. 

You show one of the bystanders how to do CPR and move to the driver’s head to give rescue breaths. Waiting for your turn, you look at the car. Someone else is slumped over in the passenger seat. 

You ask another bystander to check on her. They say she’s breathing, but unconscious. You debate about leaving her in the car, technically its better to wait for EMS to remove someone with a backboard and proper precautions, etc. but there hasn't been an actual car accident, the car basically drifted off the road at 5 mph. Whatever is going on here isn’t due to trauma, and you’d rather keep an eye on her in case she gets worse. 

They pull the passenger out of the car, placing her on the ground next to the driver. She’s unconscious but pink and breathing, with a pulse. Finally, after what feels like hours, you hear a siren wailing in the distance. The ambulance, attempting to get through traffic. The driver’s ribs are crunching underneath your hands, due to the force of your compressions. I have to say I really hate the cracking of broken ribs when I'm doing CPR, but it means that you're doing it right.

The medics arrive, scoop the patients up, and take them to the emergency department. You get back in your car, arriving at just about the same time.

The driver, a 67 year-old woman per her drivers license, still in cardiac arrest, is assigned to your colleague.

 The passenger is your patient, she’s 41 years old and unresponsive, not moving when the nurse pops in an IV. This is a critically ill patient so rather than start with a vital signs, we start with ABCs. A is for airway, she's unconscious, and not protecting her airway. Meaning she’s not awake enough to keep from choking on or aspirating her own secretions. B breathing, her respiratory rate is low at about six breaths per minute, and shallow, her chest is barely moving. In addition, her oxygen level is hovering around 70%, even after the medics put her on a 100% oxygen nonrebreather mask. A and B not ok. We need to intervene with intubation and ventilation. If we don’t do it quickly, we’re about to lose, C her circulation and her pulse. 

After intubation, her vital signs improve. The nurse tells you she's afebrile with the temperature of 98.6 Fahrenheit or 37 Celsius. Her heart rate is normal at 90 bpm. Oxygen levels improve to 95% on 100% oxygen.

OK, you have a chance to take a deep breath of your own. She’s stabilized for the moment, so it’s time to start to figure out what's going on here. Tons of things cause altered mental status and hypoxia, low oxygen, but it's unlikely both occupants of the car developed the exact same medical problem at the same exact time. Bringing us directly to a toxic exposure. 

When I say altered mental status, and a low respiratory rate, what’s the first thing most of us jump too? An opioid, currently fentanyl is at the top of the list. 

But they were driving Did I hear you say? That's not stopped people from taking opioids in the past. Did they both take them at the same time? It's a possibility. Some of you might’ve wanted to give a dose of naloxone before intubation. Not a bad idea, but since her oxygen was only 70% on 100% oxygen I’d be reluctant to wait much longer before intubation. 

What physical exam finding can should check to help us determine if this is an opioid overdose?  Question 1. Remember the third part of the opioid intoxication triad? 

A.                Muscle weakness

B.                 Loss of reflexes

C.                 Small pupils

D.                Abnormal lung sounds

Answer: C meiosis, or small pupils. If her pupils are small, I’d be fairly convinced this is an opioid overdose. You turn on the flashlight on your phone and open her eyelids. Pupils are normal. Your colleague is on the other side of the curtain, still coding the driver. You ask what the driver’s pupils look like. He says fixed and dilated, meaning large and in this case, unfortunately consistent with serve hypoxic neurological injury - ie brain damage. He asks if you have any idea what happened you say no. His patient didn’t improve with intubation, nor has CPR helped. It’s now been more than 30 minutes. He asks if anyone has any other ideas. No one does. He calls the code and announces the time of death.

You wince thinking that your patient might be headed down the same path, since you have absolutely no idea what happened to these women in this car. On the plus side, her vitals are improved and she’s holding steady. 

As usual, you’ve ordered basic labs, EKG, X-rays, urine and a head CT. Maybe we’ll find a clue, but truth be told I don’t think this is where the answers lie. We need to give this more thought. Could they have both have eaten something, shared a meal that was poisoned or contaminated? Sure, lots of poisons we’ve discussed caused arrhythmias, like v. Tach and cardiac arrest. But an ingestion causing altered mental status and hypoxia, not much I can think of if it isn’t an opioid on that list. Maybe a barbiturate, like phenobarbital, but I don’t love it. 

How about carbon monoxide exposure? I love this one. Was something wrong with the car? Causing CO to be rerouted inside, rather than out the exhaust pipe? Possible, but you saw the car, it was a new model, meaning it will have a catalytic converter, meaning the engine produces very low amounts of carbon monoxide. So low, for example, it’s impossible to kill yourself in your garage. You’ve seen movies or headlines where someone commits suicide with CO from the car in the garage. This was possible with old cars, without catalytic converters. These however, produce so little CO, you run out of gas before CO rises to lethal levels. The respiratory therapist is adjusting the vent, and you ask her to do an ABG, an arterial blood gas, and a co-oximetry or a co-ox for further evaluation. The coox will give us a CO level, worth checking, but I doubt CO is the cause. 

What about methemoglobinemia, we discussed that several episodes ago. Did one of them open a popper in the car? It’s possible, stranger things have happened, but not super likely. That said you'll get a methemoglobin level on the coax also.

If not CO, what about other gases? Some are classified as asphyxiants. They do exactly that, interfere with oxygen in the lungs. Some displace oxygen, others interfere with oxygen transport, essentially keeping the lungs from absorbing or using oxygen. This results in asphyxiation internally, rather than externally from someone putting a pillow over your face, but ends in the same result. No oxygen. Nitrogen and helium are asphyxiant gases. It’s difficult to image how these got into the patients car. 

Nothing fits, exactly. Her chest X-ray comes back normal. No fluid like pulmonary edema, no pneumonia, etc. You sit down at your desk to check in on the lab results from some other patients. A few minutes later the respiratory therapist brings you the ABG results. You frown and say was this a venous stick? When you order and ABG, you want an arterial specimen. It's fairly easy to accidentally obtain venous blood, and you can usually guess from results if the specimen was arterial or venous. Venus blood is more acidic, and not surprisingly has a lower concentration of oxygen and a higher concentration of CO2. You've worked with this respiratory therapist for a long time. She says no it wasn’t venous, so you believe her. You look more closely at the results, agreeing a venous stick can’t explain the abnormalities. The patient is acidotic, not surprising given that she was barely breathing and hypoxic. Her oxygen levels are fine, tho mildly lower than what you'd expect for someone on a ventilator. What stands out is the partial pressure of carbon dioxide. It’s extremely high. 100 mmg Hg, normal is 35-45. Even on a venous specimen, the max Pco2 is around 50.  The co-ox is normal, negative methemoglobin levels, and normal CO. 

So what causes a high carbon dioxide level? Could it account for our patient's symptoms? It's common to see high carbon dioxide levels in the setting of respiratory failure. In patients with exacerbations of asthma or COPD, chronic bronchitis or emphysema. They can't breathe and what happens when your lungs don’t work? You get Low oxygen and high carbon dioxide. Carbon dioxide in the body is very interesting. We tolerate normal levels, of course. But when it rises, it causes a severely altered mental status. Sometimes patients are somnolent and difficult to arouse. As if in an extremely sound sleep. Other times the altered mental status is agitation. 

To illustrate just how severe it can be, let me share with you a case I’ll never forget. When I was a resident, I picked up the chart of a 25 year-old man whose chief complaint was an asthma exacerbation. He'd been in the waiting room for about an hour, his triage vitals were normal. I walked in the room to see a huge guy, probably 6’5 (Almost 2 meters) and an least 250 lbs (110 kg). It was immediately clear this was not a mild asthma attack, but a severe one with impending respiratory failure. He was breathing extremely rapidly 50 breaths per minute, he could barely talk, but did his best to answer my few quick questions. He was in a tripod position, which is the classic pose when you can't breathe. Basically, leaning forward with hands or elbows on your knees, trying to maximize lung expansion and air intake. 

I called the nurse, asked her to get albuterol, a bronchodilator for a breathing treatment and steroids. She took one look at him and ran to get them. I told the patient to hang in there for a few more minutes. Instead, he started to get up off the stretcher. Surprising enough, because people who can’t breathe don’t want to move. If you’re at the gym and want to catch your breath, you don’t keep exercising. You stop. Not to mention, he’d finally gotten back for treatment. Where did he want to go? 

I asked him to sit back down and said the nurse would be right back with medicine. He did for a second, but then started talking unintelligibly and got up again off the stretcher. He lurched forward a few steps, as if he were drunk, thought he wasn’t. I tried to coax him back to the stretcher, but he was not listening to reason and stumbled out into the hallway. Several other nurses tried to help at this point, but he couldn’t be reasoned with and became increasingly agitated trying to hit me and fighting the nurses. 

I was afraid he was going to run outside, or have a cardiac arrest right in front of me. He fell down, which turned out to be fortunate. It was the only way were able to get him back on the bed, it took 4 people to lift him. 

At this point, he lost his mental status, we intubated him immediately. His blood gas showed a massively high carbon dioxide level of 100 mgHg. He was a completely normal person, who came to the ED for an asthma attack. While waiting it got worse, made his CO2 level rise, which then caused psychosis and his crazy, agitated behavior. It shows the dramatic altered mental status CO2 causes.

So what's happening with our patient? Did both the driver in the passenger have sudden asthma attacks? Obviously not. Something else is causing this elevated PCO2. There's another asphyxiant gas, Question 2. It’s time to pick your poison. Is it?

A.                Phosgene

B.                 Carbon dioxide

C.                 VX

D.                Chlorine gas

Answer: B carbon dioxide itself is considered an asphyxia gas. Phosgene is very dangerous, but it works at the level of the cells to cause energy failure, not directly hypoxia. VX we've talked about before, it causes cholinergic toxicity like organophosphates. SLUDGE and the killer bees, which our patient doesn't have. Chlorine gas is an irritant, causing shortness of breath and pulmonary edema, before it causes complete collapse. The time course is a little too quick for chlorine gas and she wouldn’t have a negative X-ray either. 

How can you get carbon dioxide toxicity? There are some unusual ways and one really common way. Let’s start with the unusual ones.  

Question 3 Toxic gas released from a lake - believed to be CO2- killed thousands of people in which country? 

A.                Morocco

B.                 China

C.                 Columbia

D.                Cameroon

Answer: Cameroon. In 1986, about 1,700 people died after toxic gas was released from Lake Nyos. The lake is in a volcanic crater. It’s not clear what caused the gas release, and the composition of the gas isn’t 100% certain either, but some pretty convincing research suggests carbon dioxide. The clinical picture fits, and high concentrations were found in the lake water. Survivors recalled hearing strong winds, disturbed animals, then lost consciousness. They woke up to thousands around them dead. It’s estimated 5,000 others survived the exposure. Many complained of cough, but interestingly the biggest problem in survivors was terrible whole body skin blistering. Mucous membranes weren’t affected, like you’d expect with chlorine gas, the blisters were believed to be pressure ulcers. We sometimes call them barb burns. If you take a barbiturate overdose, you can be unconscious for days to even a week, leading to extensive soft tissue injuries from pressure ulcers. Interestingly enough, two years earlier, also in Cameroon, at a different lake, 37 people died, from a similar toxic gas release.

Occupational exposures are probably the most common route of carbon dioxide exposure, its used in places like breweries and greenhouses. It’s acted as a knockdown gas, like we previously discussed with hydrogen sulfide gas. For example, two workers became unconscious, one died, after entering a wine fermentation tank due to CO2 buildup. It can also buildup in sewers and silos. 

It’s a big issue in submarines, you can image a bunch of people exhaling CO2, in an airtight environment. They have CO2 scrubbers on board. In one case a submersible working on an artificial reef became trapped, and 2 crew members died from CO2 toxicity. 

Random aside, it’s been used to kill rats. Yes, by infusion into burrows in cities like New York and Chicago. Its quick, relatively humane, though that’s debatable, better I guess than dying of intracranial hemorrhage from an anticoagulant rodenticide. But most of all, it doesn’t poison the food chain, like many rodenticides. If you use regular rat poison, birds that eat the rats are also poisoned. Dogs and cats are at risk. No so with CO2. 

Anyway, back to our patients. We don’t know what happened to our patients before they got into the car and we don’t know what kind of work they do, but it's a safe assumption they were well enough to think that they could drive before they this sudden collapse. I’m not getting the sense this was an occupational exposure, they weren’t in a submarine and probably weren’t fumigating rat burrows. 

There is one way to get carbon dioxide exposure all of us have probably seen or been around. Question 4 is it?

A. Detergent

B. Shampoo

C. Dry ice

Answer: C. dry ice. What is dry ice? It’s actually a lump of solid carbon dioxide. When it melts, it doesn’t become liquid like regular ice, but sublimates turning directly from solid to gas.  I’m sure you’ve been to a party with dry ice, gotten a frozen shipment with it inside, or walked past someone’s house at Halloween. Why weren't you poisoned? Because toxicity requires an enclosed space. One quick aside, you can sustain burns from touching dry ice, these are actually frostbite. So be careful, but what I want to talk about here is actually carbon dioxide poisoning. If you use dry ice with your windows open, in your backyard, or at a well-ventilated party, there’s no danger of toxicity. The amount of CO2 released is miniscule compared to levels of oxygen in the air. Nothing happens. But if, on the other hand, you're exposed to dry ice in an enclosed space, then CO2 levels in your body rise, displacing oxygen, resulting in severe toxicity.

It doesn’t take as much as you think either. The air contains 0.03- 0.04% CO2 normally. 10% CO2 is a high enough concentration to cause seizures and death. At levels of  >30%,  it causes immediate unconsciousness, and can cause cardiac arrest within a minute.

There are tragic cases of people trapped in freezers with dry ice, or driving cars or trucks with dry ice resulting in exposure. In one case, a Dippin dots ice cream salesman had dry ice in his car. His mother-in-law died and his wife nearly died from high CO2 levels. Natural disasters are risk factors for exposure, as we saw carbon monoxide and generators. A man died while transporting dry ice to use as a refrigerant before a hurricane. 

Three people died at the pool party of a Moscow influencer after dry ice was put in to the pool reportedly for “visual effects.” 30 kg of dry ice (That’s 66 pounds) was dumped into the pool. Her husband was one of the victims. 

Crime writers, this one is for you. Dry ice fumes, ie CO2 can kill someone, in a room above or next door for example, without leaving any trace. What I didn’t know before this podcast, CO2 is used to carbonate soda in fast food restaurants. An 80 yo woman died in a MacDonalds after the gas line to the soda machine malfunctioned. She stopped to use the bathroom, CO2 had collected in this enclosed space, tragically killing her.  

And OMG, there are spa treatments and things called dry bath bags, where the body is enclosed and CO2 is infused in. These are inspired by natural spring baths in Europe. It’s a neoprene bag, CO2 is then infused in from a CO2 tank. The head is outside of the bag. It’s reported that it causes the “blood vessels to open up” and apparently many patients feel relaxed and fall asleep. According to one website, it’s also, you guessed it an aphrodisiac. I know listeners of this podcast will find it hard to believe, but one of these malfunctioned, tragically causing a man’s death. 

Back to our patient. She makes a full recovery the next day. Law enforcement investigates, finding several boxes of dry ice in the back seat of the car. The women were transporting it to a party, clearly didn’t realize the risks, and unintentionally asphyxid themselves. This is a fictional case, as are all our cases, to protect the innocent. But it is based on real poisonings.

Dry ice for special effects is dangerous in an enclosed space as I said earlier. Fog machines are used in movies and parties for similar smoky effects. What toxin alcohol in fog machine juice?? Hint: we discussed it in the Halloween haunted House episode. 

A.  Diethylene glycol

B.  Ethylene glycol

C.  Isopropanol 

Follow the Twitter and Instagram feeds both @pickpoison1 for the answer. Remember, never try anything on this podcast at home or anywhere else. 

Thanks for listening. It helps if you subscribe, leave reviews and/or tell your friends. Transcripts are available at pickpoison.com. 

 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. Until next time, take care and stay safe.