Internal medicine and rheumatology specialist Siobhan Deshauer, MD, takes us through a medical case study: cardiac arrest after red meat consumption.
Following is a transcript of the video (note that errors are possible):
Deshauer: Hey, guys. I'm Siobhan, an internal medicine and rheumatology specialist. Today, I'm going to tell you about Tom, a retired high school teacher who ate a strict carnivore diet. He went all in on this meat diet, expecting health benefits, but instead it almost cost him his life.
Tom and his wife, Patty, recently returned from a fishing trip bored of eating fish day after day. Tom went to the local farmers' market to prepare for a red meat feast. When he got home, he fried it all up and they enjoyed a delicious dinner together. After dinner, Patty went out to her book club meeting and Tom went to the living room to watch the football game. While Patty and her friends were discussing a tragedy in their book, The Covenant of Water, they were blissfully unaware of a tragedy that was unfolding back at home. Tom was fighting for his life.
About an hour later, Patty returned home to a horrifying sight. Tom, who seemed perfectly fine after dinner, was now slumped over the side of the couch, unresponsive and barely breathing. In a panic, Patty called 911. After explaining the situation, the operator calmly walked her through what to do, step by step. She pressed her fingers into Tom's neck and couldn't feel a pulse. She wasn't sure if he was still breathing. The operator told Patty to bring Tom to the ground and to start CPR.
Fifteen agonizing minutes later, she finally heard the sirens approaching. Covered in sweat and tears, she yelled for them to come to the living room. Miraculously, when the paramedics checked, Tom had a pulse. It was weak and rapid, but it was there.
Within minutes, they were speeding down the highway towards the hospital. Tom was in critical condition. His blood pressure was perilously low. His heart was racing and his oxygen levels were dropping.
As they rushed him into the hospital, the medical team was ready. In these moments, when you walk into a room and you see a crashing patient, it's like time slows down as your mind is filtering through a huge amount of information in a matter of seconds. The emergency doctor's eyes darted from Tom to the cardiac monitor.
Tom was conscious and moaning, immediately giving them some reassurance that his airway wasn't blocked. But his breathing was shallow and his oxygen levels wouldn't budge above 85%, even though he was receiving the maximum amount of oxygen. His blood pressure was low, only 77 over 50, despite having an IV running fluids in as fast as possible.
We have two issues: low oxygen and low blood pressure. Our priority is getting his oxygen levels up, but in reality we have to work on both at the same time. Knowing that Tom had just had CPR for 15 minutes, where Patty was pushing on his rib cage hard enough to compress his heart and circulate his blood, it's very likely he has broken ribs. The sharp edges of a broken rib can puncture a lung and cause it to collapse.
The doctor listened to Tom's lungs carefully and he heard normal breath sounds on both sides of the chest, so his low oxygen levels probably aren't due to a completely collapsed lung. Tom winced in pain every time he was moved and even when the stethoscope was placed on his chest, so a stat portable chest X-ray was ordered, which confirmed that he did have multiple broken ribs from the CPR and a possible pneumonia on the right side.
Both of these findings could explain his low oxygen levels. Not only does a pneumonia prevent air from entering part of the lung, but Tom was in so much pain from the rib fractures that he couldn't take a proper breath in.
In this situation, when you have a patient who is critically ill, who has low oxygen levels, who just recently had a cardiac arrest, and who is still drowsy, it's critical to get control of their airway. Tom's doctors decided to intubate him, which means putting a breathing tube down his throat.
Now, for this procedure, we usually sedate patients, but a sedating medication can drop Tom's blood pressure even further, which could be deadly. He had already received 3 liters of IV fluids and his blood pressure hadn't budged. To put that into context, the average man only has 5 liters of circulating blood so that's not a good sign.
They need to intensify Tom's treatment with a medication called norepinephrine. Norepinephrine is a medication that increases the patient's blood pressure by causing their blood vessels to constrict, similarly to the way your body reacts to adrenaline in a fight-or-flight scenario, and it worked. Tom's blood pressure rose to a safer zone within minutes. Now, Tom's doctors were able to safely perform a rapid sequence intubation and hook Tom up to life support.
This is really how it goes in a critical, life-threatening scenario. You always have to stabilize your patient first and often with very little information. Then you have time to run tests and figure things out, and really nail down the diagnosis. Now, the question is why is Tom so sick? What's going on here and can we fix the problem?
At this point, all we know is that Tom is in shock. Your organs need a constant supply of oxygen and nutrients. If something happens to disrupt the amount of blood flow going to your organs, then your body goes into a state of shock. The challenge is there are many different types of shock and they are often treated differently. If you give the wrong treatment, it could be fatal.
Tom's blood work came back showing an elevated lactate level, more evidence that he is in shock and that his organs aren't getting enough oxygen. It's similar to when you sprint and lactic acid builds up in your muscles.
His blood work also shows an elevated white blood cell count and C-reactive protein, which suggests there is some kind of infection or inflammation. Remember, we did see a possible pneumonia on his chest X-ray and that could explain his blood work. For now, that's going to be our leading diagnosis, pneumonia causing septic shock.
But how does an infection lead to shock and such a shockingly low blood pressure? This is a fascinating topic and, to put it simply, in septic shock your immune system overreacts to an infection, flooding your body with chemical signals that cause your blood vessels to dilate and become leaky. That's what causes your blood pressure to drop.
We need to act quickly. The moment we even consider this could be septic shock we have to give antibiotics immediately. That's because every hour we delay giving antibiotics a patient's risk of dying increases by 8%, so now Tom's receiving IV fluids, norepinephrine, antibiotics, and corticosteroids to treat possible septic shock.
But hold on, things aren't quite adding up for me. Tom went from being completely fine to having a cardiac arrest just a few hours later. It's not really the timeline I would expect for septic shock, so what else could it be? In a middle-age man, we have to think about a cardiac cause. Could this have been a heart attack or an abnormal heart rhythm? It doesn't look like it. He had a normal echo and a normal ECG.
What about a pulmonary embolism? A large enough blood clot in his lungs could definitely drop his oxygen levels and his blood pressure. But his CT angiogram didn't show any signs of an obstruction. We can also cross off hypovolemic because he is not bleeding and he has no reason to be dehydrated, so we're left with the category of distributive shock. It still could be septic shock, but it just doesn't quite fit.
Tom's doctor went back to speak with Patty. He wanted to hear every detail she could remember. Patty took a deep breath and thought back to dinner. Tom had been feeling well that day. He hadn't been coughing or feeling sick. They had the exact same meal countless times before and he never had any issues.
Then, Patty paused. She recalled that when she was heading out for her book club Tom had mentioned that he was itchy and she just told him to put on some cream. Itching, interesting. Could this have been the first sign of an allergic reaction? Anaphylaxis is a severe, life-threatening allergic reaction and as you might remember it's one of the causes of distributive shock.
But that would be unusual, too. Anaphylaxis usually happens quickly when you're exposed to something you're allergic to. A classic example would be a bee sting that rapidly leads to hives and swelling of the lips and the throat. Any "Bridgerton" fans out there will know what I mean.
But anaphylaxis isn't always so obvious. There is a huge range of potential symptoms and rarely it is possible to have a delayed anaphylactic reaction. Tom's doctors sent off blood work looking for signs of an allergic reaction and it's a good thing they did because his tryptase level came back five times the upper limit of normal.
Tryptase is an enzyme made by your immune system. Think of it like an allergy alarm bell. When your body detects something it's allergic to, special cells will release tryptase to sound the alarm and it's not usually elevated in septic shock. Even though we saw that possible pneumonia, we can be pretty confident that Tom is actually in anaphylactic shock.
If there is one thing I really want you to remember, it's that you treat anaphylaxis with epinephrine, which is what's in an EpiPen. That's what they did. Tom's doctors quickly switched him from norepinephrine to epinephrine.
But we're not finished yet. What could have possibly caused the reaction? It doesn't sound like he was swarmed by bees and he hasn't added anything new to his diet. If we don't know the trigger, how can we prevent it from happening again? Tom's doctors called the allergy specialist to come investigate. The allergist on call spoke with Patty and she heard the same story: sausage, hamburger, itching.
But our next question was a surprise. Had Tom been exposed to any ticks recently? As you may recall, Tom and Patty had been on a fishing trip a few weeks ago and he had found a lone star tick in his belly button and he wasn't sure how long it had been there.
Why is that relevant? Well, when the tick burrowed into Tom's skin it injected a molecule called alpha-gal right into his bloodstream and alpha-gal is a carbohydrate that's found in all mammals, except humans and higher primates. When Tom's immune system came in contact with alpha-gal, it identified it as foreign and kind of freaked out and started creating IgE [immunoglobulin E] antibodies. This is a critical point because IgE antibodies are responsible for anaphylactic reactions.
Over the next few weeks, Tom's immune system pumped out tons of these antibodies, so they were ready and waiting for alpha-gal, which flooded Tom's system when he had his red meat feast. At this point, an overwhelming immune reaction took place. Chemical signals like histamine were released in huge quantities, which caused his blood vessels to dilate and his blood pressure to drop. That's what caused Tom to go into shock.
We've got a great theory, but how do we prove it? Fortunately, there is a blood test to detect IgE antibodies against alpha-gal and Tom's levels were sky-high. We finally have our diagnosis. Tom has alpha-gal syndrome.
Siobhan Deshauer, MD, is an internal medicine and rheumatology specialist in Toronto. Before medicine, she was a violinist, which is why is called Violin MD.