Vital signs go wireless

San Diego-based Triage Wireless has created, and hopes to bring to the market in the near future, a patch applied to the skin that continuously monitors a person's blood pressure, heart rate and other vital signs, and then forwards that information to their doctor's computer via wireless links.

The idea behind the AdvancedBPM system is to give doctors a far more accurate picture of a person's health, said Triage CEO Matthew Banet. Blood pressure readings are notorious for providing an incomplete picture of a person's health. Patients are in an uncomfortable environment, forced to wear an inflated armband and are often in a flimsy hospital gown. These environmental stresses can throw off the results. The doctor, meanwhile, gets only a few points of data.

"It's almost impossible to characterise someone's blood pressure in a medical office," Banet said. "But that creates problems. What if you overmedicate, or what happens if their blood pressure is low (during the test), and you miss something?"

With the AdvancedBPM system, physicians conceivably will get a more complete view of a person's vital signs during different parts of the day, including while they sleep, and over an extended period of time. The system, ideally, would also help curb spiraling medical costs by reducing the number of hospital and office visits.

Health care has become the latest obsession of high-tech companies. IBM, Accenture, Intel and others have set up divisions to devise computer systems to cut down on paperwork and improve diagnostic techniques in hospitals. Nearly 15 percent of the world's gross domestic product goes to health care, according to Louis Burns, general manager of the Digital Health Group at Intel, and could rise to 25 percent if changes aren't instilled.

AdvancedBPM patch

"The major advantage to (the AdvancedBPM system) is having continuous and ambulatory monitoring of blood pressure," said Dr. John Vasconcellos of Scripps-Green Hospital, in La Jolla, California. "Now we strap on a blood pressure cuff on these people for 24 hours."

(This system shouldn't be confused with RFID tags, a technology that has provoked controversy over the potential for it to be embedded in humans. These chips could serve as identification and a repository of information on a person's medical history, but critics worry about breaches of personal privacy.)

The AdvancedBPM system, in part, owes its heritage to the semiconductor equipment industry. The patch takes three vital signs: heart rate, pulse oximetry (the amount of oxygen in the blood) and blood pressure.

The first two are measured through an electrical sensor. "Every time the heart beats, it sends out an electrical signal," Banet said. A future version will also take temperatures.

Measuring blood pressure, however, has generally been a mechanical art. In today's systems, health professionals inflate the cuff, restrict the flow of blood at that point, and measure the pressure at the point where the natural blood flow reasserts itself.

In AdvancedBPM, the patch contains an optical sensor tuned to detect changes in the density or volume of arteries. Changes in the volume affect blood pressure. The basic technology came from a company with which Banet was once associated that made optical sensors for "seeing" whether semiconductors contained defects.

The patch has to be calibrated to each individual patient. Some people have stiff arteries, while others have large, flexible ones. While not as accurate as traditional systems for measuring blood pressure, the results so far are promising.

"We're within a few percentage points of accuracy with the cuff," he said.

Data gets transmitted from the patch via a Bluetooth connection to a handheld, which then sends it across a cellular network. Although it's doubtful that someone will try to filch your blood oxygen readings, Triage is taking particular care with privacy and security.

"We're working closely with Qualcomm," a developer of cellular and wireless technology, he said. "We do our best to protect your data."

The company will begin trials at Scripps Clinic in Torrey Pines, California, next month. (One of the company's founders, Dr. Robert Murad, sees about 25 patients a day, and about half have high blood pressure). Triage will then submit the patch for approval by the Food and Drug Administration in April 2006.

While the approval cycle for new pharmaceuticals can take years, devices like this can get approved in about 90 days, Banet said.

The company hopes to market two versions of the patch system: one for hospitals and one for home use.