Severe COVID-19 patients have ‘unprecedented’ blood clots. Here’s what doctors know

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Coronavirus patients may be at risk of potentially life-threatening blood clots, according to medical experts and emerging research.

Doctors treating those diagnosed with COVID-19, the disease caused by the novel coronavirus, are seeing patients with clots throughout the body, including in the lungs and beneath the skin’s surface.

While COVID-19 was initially believed to be a respiratory virus, there’s growing concern around the disease attacking organs like the kidneys, heart and liver.

Dr. Jeffrey Laurence, a hematologist at Weill Cornell Medicine in New York City, said the blood clots related to COVID-19 are “a major issue we haven’t seen before.”

“I get called on severe COVID patients in the intensive care unit, typically because the kidney doctor tells me that they’ve had a patient on anticoagulants [blood thinners]… and their blood is clotting. As they’re drawing the blood, it’s clotting their tube,” he said.
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“That’s unprecedented. I’ve seen that just a few times in my life, and I’m seeing that very, very frequently.”

Laurence co-authored a recent report that examined skin and lung tissue from five patients with severe COVID-19.

He and his colleagues found blood clots on the lungs of two deceased patients, and on three living patients, clots were observed beneath the skin’s surface, including on the palms and feet.

“People were coming in [to the hospital] because of their respiratory failure — many of them needing to be placed on ventilators — and then we noticed other problems,” he said.
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Another study out of the Netherlands found that out of 184 ICU patients with COVID-19, 31 per cent had blood clotting issues — a finding researchers called “remarkably high.”

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Earlier research out of China looked at a sample of 183 COVID-19 patients and found that 71 per cent of them who died had small clots throughout their bloodstream.

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“One kidney doctor said, ‘We’re going to run out of dialysis machines faster than we’ll run out of ventilators because all the dialysis machines are clogging up,'” Laurence said.

“This is a major issue.”

To try to get ahead of the problem, some hospitals are preventively treating severe COVID-19 patients for blood clots, said Dr. Michael Brown, an emergency room physician and chair of emergency medicine at Michigan State University.

“In the intensive care units, the recommendation is that they give routine antithrombotics [drugs that reduce blood clot formation] or prophylactics, which can be with an anticoagulant,” said Brown, who is also a senior editor with Cochrane’s Circulation and Breathing network.

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While patients with clots should be put on blood thinners, some hospitals are prematurely starting COVID-19 patients on higher doses of such drugs, said Dr. Michelle Sholzberg, medical director of the coagulation laboratory at Toronto’s St. Michael’s hospital.

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This can be dangerous, she said.

“All people, when they’re really sick, have an increased risk of blood clots, so we always give a little dose of a blood thinner,” explained Sholzberg, who is also an assistant professor in the University of Toronto’s laboratory medicine and pathobiology department.

“But what’s worrisome is that many doctors around the world are automatically treating patients with a higher dose. Of course, the risk associated with getting a higher dose of blood thinner is bleeding.”

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There need to be clinical trials, both Laurence and Sholzberg said, to better understand COVID-19-related clotting and effective treatment. Sholzberg and her colleagues are starting an international trial next week on the effectiveness of blood thinners on COVID-19 patients.

“We need clinical trials immediately to help us understand not just what’s actually causing it, but also for us to have the most appropriate approach to managing these patients,” Sholzberg said.

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The connection between COVID-19 and blood clots

While there is still much unknown about COVID-19, Laurence said one reason behind the spike in clots could be because the virus enters patients’ cells and sets off a dangerous reaction in the immune system, causing it to go into overdrive, which can lead to clotting.

Sholzberg explained that when people have severe inflammation — which is what happens when the body is trying to fight off infection — they have an increased risk of clotting.

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“The inflammatory system and the clotting system are so tightly related,” she said. “So the end result of really bad inflammation is clotting.”

Another possible reason is that COVID-19 patients in the ICU often have other underlying health conditions, like heart disease or diabetes, meaning they may already be at risk of negative health outcomes, including blood clots, Brown said.

What’s more, ICU patients can develop blood clots because they’re immobile, he said.

“It’s too early to understand completely what is happening with these severely ill COVID-19 patients, but they are forming blood clots more frequently than expected in intensive care patients,” Brown said.

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“We don’t know if it’s the virus itself that’s causing a pro-coagulation sort of cascade of events, or if there’s something else going on. It’s uncertain at this point.”

Questions about COVID-19? Here are some things you need to know:

Health officials caution against all international travel. Returning travellers are legally obligated to self-isolate for 14 days, beginning March 26, in case they develop symptoms and to prevent spreading the virus to others. Some provinces and territories have also implemented additional recommendations or enforcement measures to ensure those returning to the area self-isolate.

Symptoms can include fever, cough and difficulty breathing — very similar to a cold or flu. Some people can develop a more severe illness. People most at risk of this include older adults and people with severe chronic medical conditions like heart, lung or kidney disease. If you develop symptoms, contact public health authorities.

To prevent the virus from spreading, experts recommend frequent handwashing and coughing into your sleeve. They also recommend minimizing contact with others, staying home as much as possible and maintaining a distance of two metres from other people if you go out.

For full COVID-19 coverage from Global News, click here.

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