Why Covid patients are dying – So what exactly are blood clots, and why are they so dangerous? Blood clots don’t usually form in the body….unless we have, we have bleeding, for example, if we cut our finger.
That’s how we heal. The clot stops further bleeding. But sometimes, some people form clots when they are not supposed to.
Besides being mostly water, our blood is made up of a bunch of different proteins with different carbohydrates and fats. These various chemicals interact with each other, and all it takes is one piece of the puzzle to be missing, or abnormal, to totally throw off the balance of either clotting too much or not clotting enough. For example, in Hemophilia B, these patients are missing a protein called factor IX, and that’s why they bleed more than they should.
But some people could have the OPPOSITE problem, where they clot too quickly and form unwanted blood clots, which is what happens with antiphospholipid antibody syndrome, and that’s why these patients need to be on a blood thinner. So antiphospholipid antibody syndrome is not only a mouthful, but it’s a pain in the ass because it tends to cause clots in both veins and arteries.
Why Covid Patients are Dying?
But guess what, it’s not the only cause of abnormal clotting, as there are hundreds of other medical conditions that can do the same thing, such as Factor V Leiden and Prothrombin gene mutation, or antithrombin deficiency, or protein C and protein S deficiency.
Regardless of the cause, when blood clots do form, they are most commonly in the deep veins of our legs and sometimes arms, although they can form anywhere in our blood vessels. When blood clots form in our deep veins, it’s called deep vein thrombosis, and the most common symptoms are swelling and pain.
DVT is dangerous because it can break off and travel to the heart and lungs, and this is called a pulmonary embolism, which can be fatal. And there are plenty of people who die every year from pulmonary emboli. Sometimes the clot is so big that it causes death within minutes.
Thankfully not everyone who gets a blood clot in their lung dies. The most common symptoms of pulmonary emboli are shortness of breath, chest pain, and sometimes cough. They can also have lightheadedness and dizziness or even temporarily lose consciousness. And some people don’t have any symptoms. It usually depends on the size of the clot.
Sometimes, clots can form in the arteries and cause a stroke. Or if they can lodge in the coronary arteries and cause a myocardial infarction, aka a heart attack.
Or they can cut off blood flow to a leg. And there are more reports of patients presenting to the hospital, not with typical COVID symptoms, but pulmonary emboli.
So are blood clots at least part of the reason why some people with COVID are dying?
I can tell you that the number of clotting problems my colleagues see in the ICU across the country, all related to Covid, is unprecedented. But this isn’t just a bunch of doctors and nurses that I know who are reporting this. A recent Dutch study found that of the 184 patients in the ICU with Covid pneumonia, 20% were having clotting issues.
There was also a similar study in Wuhan, China, where 25% of hospitalized COVID patients had clots. Why, and how is SARS-CoV-2, which invades the cells of the lungs. Specifically, they type II alveoli; how is it causing blood clots to form in the body? When someone has a severe case of COVID, it causes a ton of inflammation within the lungs. This inflammation is what is triggering the blood clots to develop.
We knew that this happens with ARDS even before COVID came around. In ARDS, these patients usually develop microthrombi, meaning tiny clots, that form in the small blood vessels in the lungs. And these microthrombi can combine to form bigger thrombi, meaning more extensive clots.
This happens at least partly because of the cytokine storm that develops as a result of the infection. Blood clots are also a concern with seriously ill people in general, regardless of their illness, because these patients aren’t moving much, if at all, and lack of movement further predisposes them to clots.
And that’s why when patients are admitted to an intensive care unit; we usually have given them blood thinners, unless there is a reason not to; for example, if they have to bleed, we don’t want to provide those patients with blood thinners. But when we give these blood thinners, we offer them in prophylactic doses, meaning the intention is to reduce their risk of developing a clot in the first place.
But these prophylactic doses are considered low doses. And the chances of someone having severe bleeding from these tiny doses are minimal. But the blood clots with COVID, these are just a whole ‘other beast.
There’s something more going on here. So how, and why is COVID causing more blood clots than usual?
Long story short, the virus enters the alveolar cells in the lungs using the ACE2 receptor, and once it does that, it causes the cell to have fewer ACE2 receptors on its surface. This increases the amount of 3 things within the lungs: 1) inflammation, 2) formation of clots, and 3) constriction of blood vessels going to the lungs, meaning pulmonary vasoconstriction.
And guess what, every one of these things by itself can lead to low oxygen levels. So you can imagine what that means when you have all 3 of these things going on simultaneously. The way that oxygen gets into our blood from the alveoli, it has to diffuse to our capillaries.
The cytokine storm destroys the alveolus and the endothelium, and this, my friends, is a trigger for clotting. We knew this happened in ARDS even before COVID. But guess what, the virus that causes covid can invade the cells here in the endothelium because these cells have ACE2 receptors. And that can cause even more inflammation and more clotting.
And these clots can combine with other clots to form more extensive clots and travel to other parts of the body. And in another published report in the NEJM, 3 patients in the ICU had COVID, and these 3 patients developed blood clots that were significant enough to cause major blockages in blood vessels. These 3 patients were positive for antiphospholipid antibodies. These antibodies are not in the blood of the vast majority of people.
These antiphospholipid antibodies are harmful because they attack phospholipid proteins in our body, and if severe enough, they can cause significant clots to form in our blood vessels. Anti-phospholipid antibody syndrome is a condition that depends on someone’s genetics.
But these antibodies can also arise transiently in patients with critical illnesses and various infections. So do all patients with COVID who have blood clots. Do they all have this transient antiphospholipid antibody syndrome?
We don’t know yet.
The cytokine storm triggered in the lungs can affect other organs in the body, such as the heart, kidneys, and brain. And as if that’s not bad enough, just about all of the other organs in the body have ACE2 receptors, such as the heart, kidneys, and brain.
So inside the body, COVID is causing a category 10 Hurricane in some people, about 3-4% of people who get the virus. So besides looking at drugs to treat the infection, we also have to consider giving considerable doses of blood thinners to patients with severe disease, even if we cannot diagnose them with clots.
Now some might say, well, doc, why can’t you diagnose them with clots?
Easier said than done, even during regular times. But it’s significantly harder to do during this pandemic. Every test we do, whether it an ultrasound of the legs looking for clots, whether it’s getting a CT scan of the lungs looking for a clot, or CT of the brain looking for stroke, all of these things require more PPE, more potential exposure in the hospital, and sometimes more risk to the patient doing specific tests. And even if we do all these tests, if they come back negative, there is still the possibility of a false negative because no test has 100% sensitivity and 100% specificity. In other words, no test is 100% accurate.
So there will be times when you have a very sick patient with COVID in the ICU, and you don’t know if they have blood clots. The question becomes, should you give them a high dose of blood thinner, meaning, should you treat them as if they have blood clots?
Not an easy question to answer.
Because the risk of life-threatening bleeding increases when you do so, unfortunately, because this disease is so mysterious and so new, with relatively few high-quality studies, doctors don’t have much to go on when it comes to treating these patients.
We will have to make difficult decisions, especially when giving a high dose of the blood thinner in the ICU. If we see that the patient has a blood clot, then the answer is easy, it gives them a blood thinner as long as they don’t have bleeding issues. But if we don’t see blood clots, it’s a difficult decision that will have to be made on a case-by-case basis.
Also, many people want to know, is there something you can do to reduce your risk of developing blood clots? The biggest thing that people, in general, can do, is to stay active. Meaning minimize your time sitting in a chair. That’s 1 factor that makes people more prone to developing clots.
So exercise is excellent. But if you cant do that, even walking around your room, or doing some stretching exercises, or even jumping jacks if you can. Other than that, you want to take your doctor’s advice on what you should be doing to optimize your health.
Doctor Mike Hansen, MD
Internal Medicine | Pulmonary Disease | Critical Care Medicine
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