07:11pm Sunday 21 July 2019

Risk Of Stroke Associated With Bypass Surgery Technique Designed To Prevent Organ Damage

“For reasons we don’t yet understand, it appears that during rewarming, an autoregulation mechanism that protects the brain from fluctuations in the body’s blood pressure can malfunction,” says Brijen Joshi, M.D., the study’s leader and a research fellow in anesthesiology and critical care medicine at the Johns Hopkins University School of Medicine. “This could increase the chances that the brain won’t get enough blood flow and oxygen and increase the risk of brain injury.”



“You come in with a heart problem and now you can’t move a limb or you can’t speak and you have a neurological problem,” says Joshi. “We have to figure out why this is happening.”


After surgery, none of the control patients had experienced any neurological problems, while seven of the standard group had strokes and one experienced a transient ischemic attack, or TIA, a brief interruption of blood flow that’s considered a harbinger for future stroke.


Joshi and his colleagues say more research is necessary into the precise causes of the malfunction in the brain’s blood-flow regulation mechanism. Currently, there is no good monitor to alert doctors in real time that blood flow in the brain is too low or too high, says Charles W. Hogue Jr., M.D., associate professor of anesthesiology and critical care medicine at the Johns Hopkins University School of Medicine and the study’s principal investigator.

 “We measure the heart, blood pressure, kidney function and more during surgery,” Hogue says. “But there’s a huge need for a better monitor for the brain.”

To that end, the team has been developing a monitoring device that, during bypass surgery, would measure blood flow to the brain using near infrared spectroscopy, along with software that tracks changes in individual patients as they happen. When the body gets to the point where it isn’t properly regulating blood flow in the brain, doctors don’t know it in real time. If a monitoring device could alert doctors that blood flow to the brain had declined, they could quickly adjust blood pressure, restoring adequate flow and potentially avoid a stroke.

“Once we find the point at which this mechanism fails, we might be able to keep blood pressure above that threshold and prevent brain injury,” Joshi says.

The study was funded through grants from the American Heart Association, the National Institutes of Health and the Foundation for Anesthesia Education and Research Training.

Other Johns Hopkins researchers who worked on the study include Kenneth Brady, M.D.; Jennifer Lee, M.D.; Blaine Easley, M.D.; and Rabi Panigrahi, M.D.

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Media Contact: Stephanie Desmon

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