Researchers from the Army Medical University and China Academy of Engineering Physics have recently developed a hybrid device that detects blood flow changes associated with strokes. Using near-infrared light to analyze these characteristics, the portable device could be used for stroke diagnosis in the emergency setting. The researchers’ work was published online in AIP Advances on June 11.
Current Issues in Detecting Strokes
Strokes are among the most common causes of death and can result in severe physical, cognitive, and emotional defects. Roughly 90% of all strokes occur due to cerebral ischemia (lack of blood flow to the brain), however the remaining 10% are caused by cerebral hemorrhage (internal bleeding in the brain). Ischemic stroke can be treated if addressed promptly, but rarely is due to procedures that must be done first to rule out hemorrhagic stroke. Although earlier identification of ischemic stroke has been achieved by mobilizing imaging technologies, diagnosing stroke in the emergency setting could be facilitated via cheaper, more portable devices.
The Near-Infrared Hybrid Device
By combining two light measuring techniques into a hybrid device, these researchers have created what may potentially serve as this mobile tool. The technology uses diffuse optical spectroscopy to analyze the light scattered from tissues to measure oxygen and blood volume, and diffuse correlation spectroscopy to analyze fluctuations in scattered light to measure the rate of blood flow. These specific parameters are known as tissue oxygen saturation (StO2), total hemoglobin concentration (HbT), and blood flow index (BFI). The device was designed to detect changes in these metrics that are associated with lack of blood flow, indicating a potential ischemic stroke.
The team tested the instrument by placing the near-infrared probe on a human’s forearm, then inflating a cuff around their bicep to block blood flow. This artificial blockage was done to test whether their device could detect associated changes in blood flow. The researchers found that their probe successfully identified these changes, detecting an StO2 decrease of 12% in 3 minutes and an immediate 16% reduction in BFI. They also noted that the expected increases in HbT, StO2 and BFI were seen once the cuff was removed.
“We can measure blood volume, blood oxygenation and blood flow using suitable near-infrared techniques,” said study author Liguo Zhu, adding that near-infrared light penetrates 1-3 centimeters under the skin.
Another author of the study, Hua Feng, notes that their device provides a comprehensive profile of one’s blood dynamics, whereas other instruments only analyze specific aspects of blood flow. Blood characteristics associated with a stroke are complex, and Feng emphasizes the importance of obtaining as many metrics as possible in diagnosing. In addition to its ability to measure several blood flow parameters, this hybrid device presents as an inexpensive and compact diagnostic tool as well.
“(Both techniques) share the same detectors, which decreases the number of detectors (compared to other instruments),” Zhu said. “The optical switch makes the combination of incoherent and coherent light sources simple, and the custom software makes measurement quick.”
Areas for Potential Development
The researchers note that there is room for improvement, specifically in adding shorter wavelengths sensitive to deoxy-hemoglobin. The team also noted that they should create a “quantitative brain reconstruction model,” and that “there is software available that may help to achieve this goal.”
Researchers have developed a device that uses near-infrared light to monitor blood flow. The hybrid instrument which is cheap and easy to use could be used to quickly and noninvasively diagnose cerebral ischemia. #medtech #stroke https://t.co/zCrfzD58nN
— Heriot-Watt Medical Education Lab (@HeriotWattMEL) June 11, 2019