Trail of bubbles leads scientists to new coronavirus clue

A doctor checking comatose COVID-19 patients for signs of a stroke inste stumbled onto a new clue about how virus may harm lungs -- thanks to a test that used tiny air bubbles and a robot.

Dr. Alexandra Reylds, a neurologist at New York's Mount Sinai Health System, initially was baffled as she tracked “ cacophony of sound” me by those harmless bubbles passing through bloodstream of patient after patient.

Yet weird finding excited lung specialists who w are studying if it helps explain why often, sickest coronavirus patients don't get eugh oxygen despite being on ventilators.

tale illustrates how months into pandemic, scientists still are struggling to unravel myri ways coronavirus attacks -- and finding hints in surprising places.

As patients flooded New York hospitals last spring, Mount Sinai’s intensive care unit that usually handles patients with brain diseases turned overnight into a COVID-19 ward, with patients heavily sedated as ventilators kept m alive.

“When we wake m up, will we tice y have some horrible brain injury?” worried Reylds, who at first h little way to monitor brain function except to check patients’ pupils.

A bedside test called a transcranial Doppler uses sound waves to track blood flow in brain, but it was too risky for health workers to stand by patients’ hes for long periods.

So Reylds turned to a new robotic version, a heset that once positioned over patient can automatically do tracking. She used it to perform what’s called a bubble study, a commonly used, painless test for stroke risk that involves injecting saline containing tiny air bubbles into a vein. As microbubbles circulate, smallest blood vessels in healthy lungs — called capillaries — will trap and filter m out of bloodstream.

Over several nights in ICU, Reylds tested some of her sickest coronavirus patients — and repeatedly, vaSignal’s robotic Doppler kept measuring bubbles that, inste of being filtered away, were somehow reaching ir brains.

“This was really bizarre,” Reylds said. Often bubbles avoid lung filtering by slipping through a heart defect that’s a well-kwn stroke risk, but “re’s way everyone suddenly has a hole in ir heart.”

But to Mount Sinai lung expert Dr. Hooman Poor, bubble mystery might be “essentially missing link” in why se patients weren't getting eugh oxygen: Maybe abrmally dilated lung capillaries, t a heart problem, were letting bubbles sneak through.

Poor and Reylds did more tests. By end of pilot study, 15 of 18 tested patients h microbubbles detected in brain. And backing Poor’s ory, patients with most bubbles also h lowest oxygen levels, researchers reported earlier this month in American Journal of Respiratory and Critical Care Medicine .

Why would capillaries matter?

Coronavirus patients on ventilators have what’s called ARDS or acute respiratory distress syndrome, an inflammatory lung failure that when caused by or infections blocks oxygen by stiffening lungs. But coronavirus doesn't similarly stiffen lungs, Poor explained.

His new ory: Doctors kw coronavirus attacks lining of blood vessels, causing dangerous clots. bubble study suggests maybe blood is being detoured from clogged vessels to unusually widened ones — and thus flowing through too fast to properly absorb oxygen.

A rare disorder called hepatopulmonary syndrome causes same abrmality, and it’s diagsed with a bubble study.

findings are preliminary, t proof that dilated blood vessels are a problem. Still, some autopsies have linked COVID-19 to deformed lung capillaries.

Next up is a larger study that aims to see if measuring bubbles could help doctors monitor wher patients are improving or worsening.

report “I think is really going to generate a lot of talk” among lung specialists, because it's “more evidence that blood vessel is really where action is,” said Dr. Corey Kershaw of University of Texas Southwestern Medical Center, who wasn’t involved in pilot study.

He cautioned that researchers need to definitively prove a heart defect isn’t playing a role.

But, "it’s an example of, re are so many things we still don’t kw,” Kershaw ded, praising creativity used to find this latest clue.