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This is how tests to detect covid work-19 4:19
(CNN) - Dr. Kathryn Hibbert's covid-19 patient in the intensive care unit was not doing well. When her blood pressure plummeted, she tried to insert an IV line into an artery in her wrist.
A blood clot obstructed the medical device.
Frustrated, Hibbert tried again with a new needle. A blood clot also blocked that line.
Three attempts were needed to insert the IV.
"You just watch it clot right in front of you," said Hibbert, director of the medical intensive care unit at Massachusetts General Hospital. "It's rare for that to happen once, and extremely rare for that to happen twice."
Hibbert and other doctors are discovering that some patients infected with the new coronavirus have a propensity to develop blood clots, which can be fatal if the clot travels to the heart or lungs.
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"The number of clotting problems I'm seeing in the ICU, all related to covid-19, is unprecedented," wrote Dr. Jeffrey Laurence, a hematologist at Weill Cornell Medicine in New York City, in an email to CNN. "Blood clotting problems seem to be widespread in severe covid cases."
Laurence and colleagues observed autopsies of two patients and found blood clots in the lungs and just below the surface of the skin, according to a study published last week. They also found blood clots below the skin's surface in three living patients.
In the Netherlands, a study found "remarkably high" coagulation rates among covid patients in the ICU.
An international consortium of experts from more than 30 hospitals met to consider the issue. Their conclusion: It is not clear exactly why, but coronavirus patients may be predisposed to clots.
"This is one of the most talked about questions about covid right now," said Dr. Michelle Gong, chief of the critical care medicine division at Montefiore Medical Center in New York City.
At Montefiore, they began putting all covid-19 patients on low-dose anticoagulants to prevent clots, Gong said.
Not all hospitals have taken that step, but concern remains.
"It's out of the norm, and we wonder if clots are one of the reasons these patients are dying," said Dr. Todd Rice, an associate professor of medicine at Vanderbilt University Medical Center in Nashville.
'Alarming' rates of blood clots
Being in the intensive care unit, sick and lying down, can be a perfect storm for blood clots in any patient.
"Even before covid, we were on high alert for suspected clots in the ICU because they are at high risk," said Gong.
Still, doctors have a hunch that covid patients may be clotting even more than other ICU patients.
The Dutch study of 184 ICU patients with covid-19 related pneumonia found that more than 20% had clotting problems. A study of 81 patients with similar diseases in Wuhan, China, found a 25% incidence of clots.
Dr. Behnood Bikdeli, who helped coordinate the international coalition of doctors investigating the clotting problem, called those numbers "alarming."
Bikdeli, a member of cardiovascular medicine at Columbia University Irving Medical Center, noted that there are three main reasons why covid-19 patients may be at especially high risk of clotting.
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One is that the vast majority of patients who become seriously ill with coronaviruses have underlying medical problems, such as diabetes, heart disease, and high blood pressure. These patients, whether they have coronaviruses or not, have a greater tendency to clot than healthy patients.
Second, one way the coronavirus can kill patients is through a "cytokine storm," where the body's immune response is activated. Patients who experience that storm, due to coronavirus, influenza, or any other reason, are at increased risk of clotting.
The third reason is that there could be something in the new coronavirus that is causing clots.
Doctors say it's hard to know exactly what's behind what they see with covid-19 patients in the ICU.
"My gut tells me that there is probably a subset of covid patients who have really abnormal coagulation behavior, that this occurs more often than we would expect," said Hibbert, who is also an instructor at Harvard Medical School.
She quickly added, however, that doctors' instincts are "notoriously misleading" and that studies are needed to get to the bottom of how common clotting is among coronavirus patients.
A difficult solution
Although a low dose of anticoagulants to prevent clots is generally considered low risk, that may not be enough to prevent clots in some patients. However, administering higher doses could cause the patient to bleed excessively, which can be fatal.
That leaves the doctors in a puzzle. Some patients may benefit from larger doses of anticoagulants because they are very ill with covid-19, and their blood tests show that they have elevated levels of D-dimer, a substance that indicates they may have clotting problems.
Harvard doctors have proposed doing a large study on blood thinners for these patients, Hibbert said.
"There is a great need for this type of rapid testing," said Gong.
Laurence, the hematologist at Weill Cornell, noted that coagulation treatment can be so complicated that he wants to find out what's causing the clotting in the first place.
"We are trying to block what is causing it," he said. "There is over-exuberant coagulation with covid patients, and we're trying to get ahead of ourselves."
As studies resolve this, doctors are more vigilant with their covid-19 patients.
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Hibbert described how a nurse recently had to constantly administer a blood thinner called heparin to a patient with covid-19 while the patient was on kidney dialysis, because clots continued to clog the tube in the machine.
“We had the nurse at the bedside administering heparin to prevent the machine from clotting. That is very rare, "said Hibbert.
Hibbert said he looks forward to the day a study determines how often covid-19 patients have clotting problems and what to do about it.
"This is one of the many challenges in caring for critically ill patients and trying to decide if what is being seen by the bedside is rare and happens by chance, or if it is part of a larger pattern that could change your practice." he concluded.
coronaviruscovid-19