At the University of Missouri, a team of researchers developed a custom finger clip device that can continuously measure a variety of vital signs, including blood pressure. The novel device represents a new way to measure vital signs and contains two commercial photoplethysmography (PPG) sensors that operate at two different points on the finger. This approach allows researchers to simultaneously calculate pulse wave velocity and also measure blood oxygen saturation, body temperature, heart rate, and respiratory rate.
Continuous blood pressure measurements can reveal trends that a single measurement can miss. In addition, the mere act of measuring a person’s blood pressure in a doctor’s office can cause increased anxiety, leading to a change in blood pressure, a phenomenon known as “white coat syndrome.” . Clearly, continuous monitoring that takes measurements non-invasively and discreetly throughout the day is preferable.
“Usually, calculating someone’s blood pressure in a hospital or clinic involves wearing an inflatable cuff wrapped around their arm, but there are three problems with that method: it can cause damage to someone’s arteries if done repeatedly over a period. short of time; people’s blood pressure may rise due to nervousness; and it can take up to 30 seconds to complete, ”said Richard Byfield, one of the leaders in the development of the new device. “Our device can record a person’s blood pressure in five seconds by using optical sensors attached to the fingertip that measure the amount of light reflected by blood vessels below the surface of the skin.”
Once the clip obtains the velocity data from the pulse wave, it transmits it wirelessly to a computer, where it is interpreted by machine learning algorithms and calculates the blood pressure. So far, in tests with volunteers, the clip has shown that it can measure systolic blood pressure with an accuracy of about 90% and diastolic pressure with an accuracy of 63%.
The robust nature of the clip is key to ensuring that the PPG data is reliable. “Normally, there are some problems with the PPG sensors,” Byfield said. “One is called artifact movement: if you move a PPG sensor while it is reading, it can affect the waves that are being recorded. On top of that, we found that pressure differences can alter the waves, but with a finger clip design, a spring provides constant pressure. Another reason this method hasn’t been explored much before is that these finger clips usually only have one sensor, but we have two sensors on our device. “
To study in IEEE Sensor Journal: Towards a robust estimate of blood pressure from pulse wave velocity measured by photoplethysmography sensors
Flashbacks – Accurate blood pressure measurement without cuff on a smartphone; Portable monitor provides continuous blood pressure data