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Doctors checking COVID-19 comatose patients for signs of stroke instead came across a new clue about how the coronavirus can damage the lungs
Instead, a doctor checking comatose COVID-19 patients for signs of stroke came across a new clue about how the virus can damage the lungs – thanks to a test that used tiny air bubbles and a robot.
Dr. Alexandra Reynolds, a neurologist at Mount Sinai Health System in New York City, was initially taken aback when she traced the “cacophony of sound” made by these harmless bubbles passing through the bloodstream from patient to patient.
Still, the bizarre discovery has excited lung specialists who are now studying whether this helps explain why sickest coronavirus patients often don’t get enough oxygen while on ventilators.
The story illustrates how months after the start of the pandemic, scientists are still struggling to unravel the myriad ways the coronavirus attacks – and find clues in surprising places.
As patients flooded New York City hospitals last spring, the Mount Sinai Intensive Care Unit, which typically cares for brain disease patients, turned into a COVID-room overnight. 19, the patients being heavily sedated because the ventilators kept them alive.
“When we wake them up, will we see that they have a horrible brain injury?” worried Reynolds, who at first had little means to monitor brain function except to check patients’ pupils.
A bedside test called transcranial Doppler uses sound waves to track blood flow in the brain, but it was too risky for health workers to stay next to patients’ heads for long periods of time.
So Reynolds turned to a new robotic version, a helmet that, when positioned over the patient, can automatically track. She used it to do what’s called a bubble study, a commonly used and painless test for stroke risk that involves injecting a saline solution containing tiny air bubbles into a vein. As the microbubbles circulate, the smallest blood vessels in the healthy lungs – called capillaries – will trap them and filter them out of the bloodstream.
Over several nights in the intensive care unit, Reynolds tested some of his sickest coronavirus patients – and on several occasions, NovaSignal’s robotic Doppler continued to measure bubbles which, instead of being filtered, somehow hit their brain.
“It was really weird,” Reynolds said. Often times the bubbles bypass lung filtering by sliding through a heart defect which is a well-known stroke risk, but “there’s no way everyone suddenly has a hole in their heart.”
But for Dr Hooman Poor, a Mount Sinai lung specialist, the mystery of the bubbles could be “essentially the missing link” as to why these patients were not getting enough oxygen: perhaps abnormally dilated pulmonary capillaries, not one. heart problem, let the bubbles slip through. .
Poor and Reynolds did more testing. At the end of the pilot study, 15 of the 18 patients tested had microbubbles detected in the brain. And to support Poor’s theory, patients with the most bubbles also had the lowest oxygen levels, researchers reported earlier this month in the American Journal of Respiratory and Critical Care Medicine.
Why do capillaries matter?
Patients with coronavirus on ventilators have what is known as ARDS, or acute respiratory distress syndrome, an inflammatory lung failure that, when caused by other infections, blocks oxygen by stiffening the lungs. But the coronavirus doesn’t stiffen the lungs the same way, Poor explained.
His new theory: Doctors know that the coronavirus attacks the walls of blood vessels, causing dangerous clots. Studying the bubbles suggests that blood may be diverted from clogged vessels to unusually enlarged vessels – and therefore flowing too fast to properly absorb oxygen.
A rare disorder called hepatopulmonary syndrome causes the same abnormality, and it is diagnosed with a bubble study.
The results are preliminary and do not prove that dilated blood vessels are a problem. Yet some autopsies have linked COVID-19 to deformed lung capillaries.
The next step is a larger study to see if measuring bubbles could help doctors monitor whether patients are improving or getting worse.
The report “I think this is really going to generate a lot of discussion” among lung specialists because it is “further evidence that the blood vessel is really where the action is,” said Dr Corey Kershaw of the University of Texas Southwestern Medical Center, which did not participate in the pilot study.
He warned that researchers must definitively prove that a heart defect does not play a role.
But, “This is an example of, there is so much we still don’t know,” Kershaw added, praising the creativity used to find this latest clue.
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The Associated Press’s Department of Health and Science receives support from the Department of Science Education at the Howard Hughes Medical Institute. The AP is solely responsible for all content.
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