measurement using cuff-free devices in the 2022 Annual Review of Biomedical Engineering . “ For example , if patients continue to see that their blood pressure is high , they may finally become compliant in taking their medications .”
Leaving the cuff behind The measurement of blood pressure goes back almost three centuries ( see sidebar ), leading to the procedure that we all know and that our family doctor performs when we have checkups : A cuff goes around our arm and is inflated , then deflated , in a controlled manner , to determine our maximum and minimum blood pressure .
But the use of inflatable-cuff blood pressure monitors has some drawbacks . For one thing , unless people have home monitors — and a survey of adults ages 50 to 80 in the United States found that only 55 percent of hypertension patients surveyed owned one — they must go to a pharmacy , doctor ’ s office or health center to learn what their blood pressure is .
Another barrier is that repeated inflation and deflation of the cuff is disruptive and can cause difficulties when , for example , a patient is in the hospital and needs frequent blood pressure monitoring . And a third drawback is that since cuffs don ’ t allow continuous measurement of blood pressure , they ’ re only providing a measurement at a specific moment .
The new cuffless devices promise to reveal a more complete picture of physiologic changes in blood pressure that cannot be picked up with spot measurements , and instead give a truer blood pressure profile , says Alberto P . Avolio , a biomedical engineer at Macquarie University in Sydney , Australia , a coauthor of the article in the Annual Review of Biomedical Engineering .
The various cuffless measuring devices are based on methods that , instead of directly determining blood pressure , use sensors to capture various indirect signals . These signals are processed by different algorithms or sets of mathematical procedures to obtain the blood pressure values . It is like inferring fever by measuring an increase in palpitations and sweating instead of using a thermometer , or divining the result of a soccer match from outside the stadium by listening to the screams of the spectators .
One of the detection methods uses optical sensors . The technique is based on the principle of photoplethysmography or PPG : It consists of illuminating a segment of the skin and analyzing the difference between the light that is emitted by the instrument and how much is detected by a photoreceptor . This difference depends on the diameter of the artery , the blood volume and the concentration of hemoglobin ( the oxygen-carrying protein ) at the measurement site . During the systolic phase , when the heart pumps blood , the difference between emitted and reflected light will be at its maximum , because there will be more blood flow and
To Table of Contents
Accessibilty for All 31