Marathon surgery can be dangerous enough without the threat of blood clots forming in the patient. To counter that, surgeons administer blood thinning drugs throughout a procedure, but knowing when to do so often requires a separate lab test, which slows down the surgery. By shining light through the patient's blood, researchers at the University of Central Florida (UCF) have developed a new system that gives surgeons real-time feedback and alerts them at the first sign of a clot.

Although they're handy for stopping you bleeding out every time you stub your toe, blood clots are troublemakers when they form inside the body. Strokes and pulmonary embolisms can occur as a result, or during surgery they can clog the cardiopulmonary bypass pump – a machine that does the job of the heart and lungs while surgeons are working on those organs.

To keep the blood pumping properly, doctors use blood thinners, but even then, a blood test is still required every half hour or so. That process can take up to 10 minutes in a lab, leaving the surgeons with large gaps in their knowledge of the patient's health, and during procedures that last several hours, those gaps add up to a lot of wasted time and unnecessary risk.

But the UCF team's new device removes the need for that process altogether. Instead, a patient's blood can be continuously scanned for the first signs of clotting throughout an operation, keeping the surgeons free to focus on the task at hand. By hooking an optical fiber up to a heart-lung machine, the system can shine a light into the blood as it's pumped through the tubes, and monitor how that light is bounced back to the instrument. If it detects that the vibrations of the red blood cells are slowing down, a clot is starting to form and it's time for a new dose of the blood thinning medication.

"It provides continuous feedback for the surgeon to make a decision on medication," says Aristide Dogariu, inventor of the technology. "That is what's new. Continuous, real-time monitoring is not available today. That is what our machine does, and in surgeries that can last for hours, this information can be critical."

So far, the device has been tested during 10 procedures on infants at the Arnold Palmer Hospital for Children in Orlando, with promising results. Having proven the concept, the team is now working on expanding the study.

"I absolutely see the technique having potential in the intensive care setting, where it can be part of saving the lives of critically ill patients with all kinds of other disorders," says William DeCampli, a pediatric surgeon at Arnold Palmer and co-author of the study.

The research was published in the journal Nature Biomedical Engineering.

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