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.