It’s a routine part of most doctor’s visits: a healthcare professional wraps a cuff around your upper arm and then inflates the cuff so it squeezes your arm. Within seconds, the cuff starts to deflate and numbers register on the device’s gauge – an upper number, which measures the pressure in your arteries when your heart beats (systolic pressure), and a lower number, which measures the pressure in your arteries between beats (diastolic pressure).
But what if you could measure your blood pressure at home, without the cuff -- just by wearing a pair of customized “smart” sneakers, or by taking a two-minute video selfie?
Though nearly half of adults in the United States have high blood pressure, millions of Americans with the condition aren’t aware they have it, in part, because most people don’t experience any signs or symptoms. Some people experience “masked” hypertension: normal blood pressure readings at the doctor’s office, but elevated readings at home. One in five adults suffers from the opposite phenomenon, called “white coat hypertension,” which is when blood pressure readings are higher when taken at the doctor’s office compared to other settings. High blood pressure, if left untreated, can increase one’s risk of severe complications, including heart attack and stroke. Patients with untreated white coat hypertension are twice as likely to die from heart disease than people with normal blood pressure, according to a recent study led by Jordana B. Cohen, MD, MSCE, an assistant professor in the division of Renal-Electrolyte and Hypertension.
At a time when more than 110 million adults in the United States have high blood pressure – defined as a top reading of at least 130 or a bottom reading of 80 – researchers are testing innovative solutions to make blood pressure measurement easier and more convenient than ever before. But, like many fitness trackers and wearables that now monitor and track health-related information, questions around the accuracy of these tools remain.
“If this innovation gets more people excited to check their blood pressure, I’m all for it. But the most important component is accuracy because if the readings aren’t accurate, the device isn’t providing any value,” Cohen said. “Inaccurate readings can lead to people falsely assuming they have normal blood pressure, or becoming anxious when they see false elevated levels. That’s why we encourage patients to use out-of-office monitoring devices that are validated.”
Emergence of Smart Devices, “Smart” Sneakers to Test Blood Pressure
In late June, Under Amour filed a patent application for a sneaker model that includes a detector in the bottom that can take a user’s blood pressure reading, according to the Baltimore Business Journal. A separate sneaker model, included in the same application, would connect to a wearable device that would take a user’s blood pressure. Depending on the specific levels, the shoe’s sole could then adjust to help improve blood flow.
Earlier this month, Circulation: Cardiovascular Imaging, an American Heart Association journal, published results of a study in which researchers used a face-scanning app to measure participants’ blood pressure. Throughout the two-minute selfie videos, which researchers say they hope to reduce to 30 seconds, ambient light penetrates the skin’s outer layer, allowing digital optical sensors in the smartphone to extract blood flow patterns. The phone, which is equipped with transdermal optical imaging software, uses the patterns to predict blood pressure.
“To manage and prevent (high blood pressure), regular monitoring of one’s blood pressure is essential,” wrote the study’s lead author Kang Lee, PhD, professor and research chair in developmental neuroscience at the University of Toronto in Canada. “Cuff-based blood pressure measuring devices, which highly accurate, are inconvenient and uncomfortable.”
Like Lee, Cohen and Ray Townsend, MD, director of the Hypertension Program at the Hospital of the University of Pennsylvania, advocate for increased out-of-office blood pressure monitoring. While they are excited about the innovation, they note that most of the new technologies aren’t ready for market. For example, researchers only tested the face-scanning technology in people with normal blood pressure, and not in anyone with extremely dark or fair skin.
Townsend said the smart devices are considered a recreational approach to blood pressure measurement, so they aren’t governed by the same set of rules as a blood pressure monitor that’s specifically sold for health care purposes.
“The degree of precision, accuracy and validation in smart phone devices, shoes or gloves aren’t under the same level of scrutiny,” Townsend said. “Consequently, there’s some skepticism about whether these devices are anywhere near primetime.”
Measuring Blood Pressure at Home
For validation of clinical accuracy, current guidelines recommend blood pressure devices have peer-reviewed publications showing they have been tested using internationally accepted protocols. However, with the increase in available devices, it’s not always easy for consumers to identify devices that meet international standards.
Both Cohen and Townsend, along with a team of other researchers, are working with the American Medical Association to develop a national validated device listing site. The site, which is expected to launch in the coming months, will list the validated devices that people can buy off the shelves. In the meantime, Cohen refers people to STRIDE BP, an international scientific nonprofit that offers lists of validated blood pressure monitors.
Upon purchasing a blood pressure monitoring device, patients should bring it to their doctor’s office to have it checked against a manual reading, Cohen says. She notes out-of-office devices are particularly prone to inaccuracies for people who are pregnant and those with atrial fibrillation – an irregular and often rapid heart rate.
In addition to selecting the right device, patients also adhere to a few steps to get an accurate reading.
“The biggest sins I see regularly are patients using a cuff that’s too small, or people who don’t wait and sit still for five minutes before inflating the cuff,” Townsend said.
Other recommendations include: don’t exercise or drink caffeine 30 minutes prior to the measurement, keep your cuffed arm on a flat surface at heart level and sit upright, with your back straight and feet flat on the floor. Afterward, wait one minute and then re-take your blood pressure.
“It’s important to empower patients to be more involved in their own healthcare,” Cohen said. “But if it’s not accurate, there’s no value in it.”