Transfusion medicine

Emergency room doctors often have only a few minutes to determine which patients are in need of a blood transfusion. But currently doctors have no direct method to assess the health of one of the most critical component of the blood platelets. These tiny blood cells play a huge role in helping blood clot after an injury.

Mechanical Engineering

Now researchers at the University of Washington have created a novel system that can measure platelet function within two minutes and can help doctors determine which trauma patients might need a blood transfusion upon being admitted to a hospital. The team will publish its results March 13 in Nature Communications.

“Our system requires a tiny amount of blood to look at how healthy platelets are in real time,” said co-corresponding author Nathan Sniadecki, an associate professor in the UW Department of Mechanical Engineering. “We found that platelet function is a far better measure of platelet health and whether a trauma patient will need a blood transfusion than current methods.”

Risk of bleeding

Platelets are the first responders to any sort of damage to blood vessels. “They act as a sort of instant patch,” Sniadecki said. “They become activated and stick to the damage, and then they rapidly change their shape to stretch and reach out for more of the wound surface or other platelets. Then they begin to come back together to compact and add strength to a clot.”

In patients who’ve experienced trauma, however, platelets can lose the ability to do their jobs, including becoming less able to apply the forces needed to stop bleeding. “When trauma patients come into the ER; we use a variety of methods to estimate their risk of bleeding, but none of these tests tells us specifically about platelet strength;” said co-corresponding author Dr. Nathan White; an associate professor of emergency medicine at the UW School of Medicine.

Platelet-activating molecule

White, Sniadecki and their team designed a microfluidic device that measures platelet forces in real time. First, the researchers inject a blood sample into the device. As the blood flows through it; the cells hit an obstacle course: tiny blocks and posts jutting up from the base of the device.
This activates the platelets. They feel a massive force when they flow over the blocks, and then the surface of both the blocks and the post are coated with a platelet-activating molecule. “The block and post structures act like a mini wound surface;” said lead author Lucas Ting; who conducted this research as a mechanical engineering doctoral student at the UW.
“The platelets attach between the block and post, and they start to snowball. They aggregate to form a miniature plug that then begins to contract and pull the post toward the block. Based on how far the post moves, we can determine how functional the platelets are.”