A new optical method for continuous bedside monitoring of cerebral blood flow (CBF) incorporates a noninvasive probe placed on the surface of a patient's head to measure fluctuations in near-infrared (NIR) light that has traveled through the skull and into the brain, then back out to the tissue surface. The representative device, designed at the University of Pennsylvania (Philadelphia, PA), has allowed researchers from Penn Medicine and the Department of Physics & Astronomy in Penn Arts and Sciences to make an important discovery that could improve treatment for stroke—a.k.a. cerebrovascular accident (CVA).
After suffering acute stroke, most hospital patients are kept flat for at least 24 hours to increase CBF in vulnerable brain regions surrounding the damage. Research using the new device shows that while a flat head of bed (HOB) did increase CBF in the damaged hemisphere for most stroke patients, a substantial minority (~25%) showed more CBF with their head elevated.
The NIR light fluctuations measured by the approach—caused by red blood cells moving through tissue—have been shown to accurately track CBF in underlying brain tissue. The novel technique, called diffuse correlation spectroscopy (DCS), has proven more sensitive for detecting CBF changes with HOB positioning than transcranial Doppler, which uses acoustic waves to quantify blood flow velocity of the large arteries supplying the brain.
"This study illustrates the potential of using advanced technology to make individualized treatment decisions in real time," said senior author John A. Detre, MD, professor of Neurology and Radiology in the Perelman School of Medicine at the university. Stroke is the leading cause of disability in industrialized nations and a leading cause of death.
The U.S. Patent Office has granted patent 8,082,015 to the University of Pennsylvania for the optical CBF technology. Besides application to neurological disorders, it is being tested in a number of other clinical populations in whom CBF changes are relevant.
1. C.G. Favilla et al., Stroke, 45, 1269–1274 (2014); doi:10.1161/strokeaha.113.004116.