When a fetus develops, the baby’s lungs are filled with fluid, and oxygen comes directly from the placenta. This oxygenated blood bypasses the lungs to reach the rest of the body through a vessel called the ductus arteriosus. After birth, babies use their lungs to breathe, and the ductus arteriosus typically closes within several days. But for nearly 65% of pre-term infants, the vessel fails to close. This condition, called patent ductus arteriosus, or PDA, shifts blood flow into an abnormal path which can strain the heart, congest the lungs and steal blood and oxygen from the newborn baby’s brain and other organs. Physicians must decide whether to attempt to close the PDA with medications or an implanted device, both of which have risks. Accurately measuring blood flow to the newborn’s organs could help with this important decision. However, there is no true blood flow measurement that practically works for clinical use. Now, researchers have discovered a novel, non-invasive way to measure blood flow to the brains of newborn children at the bedside – a method that has the potential to enhance diagnosis and treatment across medicine.

A team of researchers at Michigan Medicine (Ann Arbor, MI, USA) has developed a real-time ultrasound color flow technique that relies on 3D sampling to measure blood flow. They tested the method on 10 healthy, full-term babies, obtaining total brain blood flow measurements that closely match those using more invasive or technically demanding techniques. There are many surrogate methods used in lieu of true blood flow, such as blood flow velocity. But true blood flow requires knowing the velocity of the blood in relation to the area it covers. The new technique measures true blood flow by calculating blood flow flux over a surface across ultrasound beams. The color image is captured in 3D.

With a non-invasive, true measure of blood flow, researchers say the technique could be applied to address blood flow to organs including the brain, the liver and kidneys in many disease states including congestive heart failure, sepsis and shock. The method also has the potential to be applied almost anywhere an ultrasound can image, being used for anything from assessing need for organ transplants to identifying issues during surgical procedures.

“There are several other methods of measuring blood flow, but they are cumbersome and often require intravenous contrast agents, with babies being sedated or restrained in a scanner,” said Jonathan Rubin, M.D., Ph.D., professor emeritus of radiology at University of Michigan Medical School. “But pre-term babies are in incubators; they are fragile, and these techniques can be dangerous. This ultrasound technique could be used routinely in neonatal intensive care units, which could significantly impact outcomes for pre-term babies with this condition.”

“In the Neonatal Intensive Care Unit, we must make assumptions every day based on indirect measures to determine how our treatments affect blood flow to the organs of critically ill newborns,” said Gary Weiner, M.D., clinical associate professor of pediatrics at U-M Medical School and medical director of the Brandon Neonatal Intensive Care Unit at U-M Health C.S. Mott Children’s Hospital. “Having a safe, rapid, accurate bedside tool that allows us to measure true blood flow could be a game changer.” 

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