Finger clip could find use in less stressful blood pressure tests
Having your blood pressure measured via an inflatable arm cuff can be stressful, potentially causing that pressure to be higher than normal when the reading is taken. A new finger clip device, however, is promised to make the process quicker and easier for patients.
Presently being developed at the University of Missouri, the prototype tool looks much like the finger-applied oximeters that are currently used to read patients' blood oxygen levels. And just like an oximeter, it shines light through the skin, analyzing the light which is reflected back by the blood within the finger.
The new device does so at two points along the length of the finger, however, using two photoplethysmography (PPG) sensors. By measuring the millisecond lag between the times at which each pulse of blood is detected by each sensor, it's possible for a linked computer to calculate the patient's pulse wave velocity – in other words, the speed at which the blood is travelling through their bloodstream.
Previous studies have shown that there is a strong correlation between pulse wave velocity and blood pressure. In fact, when the finger clip was tested on 26 volunteers, it proved to be 89 percent accurate at gauging their systolic blood pressure, and 63 percent accurate at measuring diastolic blood pressure. It is believed that those numbers should improve once the technology is developed further.
Importantly, the device doesn't require the application of a tight, uncomfortable arm cuff, plus it can obtain readings within just five seconds. And as an added bonus, it can also be used to measure a person's heart rate, blood oxygen saturation, body temperature and respiratory rate.
A paper on the research, which is being led by grad student Richard Byfield and Assoc. Prof. Jian Lin, was recently published in the IEEE Sensors Journal.
Source: University of Missouri