A Wristwatch that Monitors Blood Pressure

 

This wireless monitor from Healthstats detects blood pressure by detecting the shape of a pressure wave as blood flows through an artery.
Healthstats

 

 

Researchers hope a device that tracks vital signs around the clock will help patients better control their blood pressure.

 

 

MIT Technology Review, by Emily Singer  —  Although high blood pressure can be monitored, and treated effectively, with a number of drugs, a quarter of the people with the condition don’t even know they have it, according to the American Heart Association. Of those who know they have high blood pressure, only two-thirds get treatment, and fewer than half have it under control.

Now a new wireless monitor from Hewlett-Packard and a Singapore company called Healthstats aims to make it much easier for patients and doctors to monitor blood pressure. The device, which has the size and look of a wristwatch, can monitor pressure continuously—which provides a much more accurate picture than infrequent readings in the doctor’s office. Until now, the only way to do such continuous monitoring has been with a cumbersome inflatable cuff for the arm or wrist.

The new monitor comes with related software designed to keep patients and doctors informed of the wearer’s vital signs, including blood pressure. Data is transmitted from the device to the user’s cell phone, and then to the cloud, where clinicians can review it. Patients and their doctors can view 24-hour graphs of blood pressure, and the system can sound alerts when it detects abnormalities in pressure or other measures.

The research is part of a growing effort to use wireless monitors to capture round-the-clock medical data outside of the hospital. Physicians hope such devices will inspire patients to better monitor their own health, and help uncover difficult-to-diagnose conditions, such as nighttime hypertension.

Unlike standard equipment, the Healthstats device relies on a sensor that rests against an artery in the wrist and detects the shape of the pressure wave as blood flows through it.  (The device is first calibrated with a standard blood pressure monitor.) “Together with algorithms we have developed, the indices can be processed to get heart rate, diastolic and systolic pressure, and other measures,” says Ting Choon Meng, a physician and Healthstats CEO.

 

A wired version of the Healthstats monitor is currently in use in hospitals in Singapore and other parts of the world. The company began developing its wireless version about a year ago, in collaboration with HP, which has developed a software platform that can be paired with this and other wireless monitors.

“We have developed an application for a patient and physician portal where all this information will be delivered to the appropriate person,” says Lloyd Oki, vice president of Asia Pacific sales, communications, and media solutions at HP. “It could be an adult buying a mobile monitoring device for their parents, or a younger person being monitored, with the information sent to a clinician or adult caregiver.” Such devices might also be of interest to professional athletes, he says, perhaps calling attention to seemingly healthy athletes with undetected heart issues.

One issue still to be answered is how accurate the device is at measuring blood pressure when people are moving around. Healthstats has shown that the monitor works as well as other measures when users are sitting still, but has yet to publish comparable results for people in motion. “The bottom line from my standpoint is that it is a great idea that still needs to be fine-tuned to be usable in ambulatory patients,” says Dena Rifkin, a physician and assistant professor of nephrology at the University of California, San Diego.

A clinical trial underway in Singapore is designed to assess how the device affects patient and physician behavior, rather than its accuracy. A hundred patients, some healthy and some with a high risk of chronic illness or a history of strokes, will use the device over eight weeks. “Every morning, they will receive a summary of the findings via SMS,” says Ting. “A call center will look at data round the clock and intervene if needed.”

Researchers will then determine whether the monitor helped people with hypertension better control it, and whether it could detect abnormal blood pressure in people who were seemingly healthy. As more people measure their blood pressure throughout the day and night, physicians are discovering different patterns of abnormal blood pressure, such as hypertension only at night, or blood pressure spikes in the early morning, which may contribute to the high percentage of strokes that occur early in the morning, says Ting.

 

 

 

A Nightshirt to Monitor Sleep

 

Sweet dreams: The Somnus sleep shirt has embedded fabric electronics to monitor respiration.   Nyx Devices

 

 

 

A newly developed smart shirt detects the wearer’s stage of sleep via respiration patterns.

 

 

MIT Technology Review, by Emily Singer  —  What if your pajamas could tell you how well you slept? That’s the dream of startup Nyx Devices, which has developed a nightshirt embedded with fabric electronics to monitor the wearer’s breathing patterns. A small chip worn in a pocket of the shirt processes that data to determine the phase of sleep, such as REM sleep (when we dream), light sleep, or deep sleep.

“It has no adhesive and doesn’t need any special setup to wear,” says Matt Bianchi, a sleep neurologist at Massachusetts General Hospital and co-inventor of the shirt with Carson Darling, Pablo Bello, and Thomas Lipoma. “It’s very easy—you just slip it on at night,” says Bianchi, who has no formal role with Nyx Devices.

When people with sleep disorders spend the night in a sleep lab, they are hooked up to a complex array of sensors that monitor brain activity, muscle activity, eye movement, and heart and breathing rate. Nyx’s Somnus shirt dramatically simplifies this by focusing only on respiration. “It turns out that you can tell if someone is awake or asleep and which stage of sleep they are in purely based on breathing pattern,” says Bianchi. “That’s a much easier signal to analyze than electrical activity from the brain.”

During REM sleep, the respiratory pattern is irregular, with differences in the size of breaths and the spacing between them. Breathing during deep sleep follows an ordered pattern, “like a sine wave,” says Bianchi. “And the breath-to-breath differences are very small.” The lighter stages of non-REM sleep fall somewhere in between. “The motivation behind the shirt is to allow repeated measurements over time in the home,” he adds. Users can log their habits, such as coffee or alcohol intake, exercise, or stress, and look for patterns in how those variables affect their quality of sleep.

Analyzing sleep stages based on respiration is still considered experimental. But Bianchi is now testing the device on patients who come to his sleep clinic who are also assessed using standard technology, known as polysomnography. The team will soon begin home tests of the shirts to further validate its use outside of the lab. The company hopes to have a commercial product available by summer of 2012 for less than $100.

The shirt is part of a growing number of devices that people can use to monitor sleep at home. The simplest, including an iPhone app, use accelerometers to measure movement, giving a rough gauge of when people fall asleep and wake up. A more sophisticated consumer device that monitors electrical activity from the brain and muscles, called the Zeo, came on the market two years ago.

 

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While Nyx envisions the shirt as a consumer product, Bianchi wants to use it for his patients. Bianchi’s previous research has shown that people with insomnia often underestimate how much they sleep, so he wants to determine whether giving them an objective way to measure sleep will help them reassess their condition and improve quality of sleep. “It will be a game changer for my clinical practice,” he says. “There are zero objective tools available to physicians to assess insomnia.”