Investigating the Cause of Brain Damage after Cardiac Bypass Surgery

The practice of cooling and then re-warming a patient during cardiac bypass surgery, done to prevent organ damage, may impair the body�s mechanism that controls blood flow to the brain, which could increase the patient�s likelihood of suffering a stroke.

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The research team, led by Brijen Joshi, MD, research fellow in anesthesiology and critical care medicine at the medical school, found that the mechanism tended to malfunction as the body was being re-warmed. Both groups of patients who were followed for the study underwent bypass surgery, but the patients in one group, which had shorter operations, were kept at normal body temperature throughout the procedure to serve as a control group.

After surgery, the team found that seven of the 127 patients in the standard bypass group had experienced stroke and one patient had a TIA. None of the patients in the control group experienced neurological problems.

“We measure the heart, blood pressure, kidney function, and more during surgery,” said Charles W. Hogue Jr, MD, associate professor of anesthesiology and critical care medicine at the medical school and the study’s principal investigator. “But there’s a huge need for a better monitor for the brain.”

To accomplish this, the research team is now developing a monitoring device that could track blood flow to the brain using near infrared spectroscopy, as well as software that tracks changes in individual patients as they occur. This device would alert physicians when blood flow to the brain had declined, allowing them to restore blood flow quickly and prevent a stroke.

Anesthesia and Analgesia

“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,” said Joshi, who is also first author of the study published in

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The practice of cooling and then re-warming a patient during cardiac bypass surgery, done to prevent organ damage, may impair the body’s mechanism that controls blood flow to the brain, which could increase the patient’s likelihood of suffering a stroke, according to new research from Johns Hopkins University School of Medicine