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The newspaper of The Johns Hopkins University February 5, 2007 | Vol. 36 No. 20
Space Technology Benefits Medical Community

Skin and ambient temperatures are recorded by the device's two sensors.

Hopkins collaborators test a monitor to characterize Raynaud's disease

By Kristi Marren
Applied Physics Laboratory

A small group of researchers at the Applied Physics Laboratory, in collaboration with physicians from the Johns Hopkins Scleroderma Center, developed and recently completed initial trials for a miniature device to help physicians characterize Raynaud's disease and measure treatment effectiveness.

The device was developed at the request of Frederick Wigley, director of the Scleroderma Center, who had read about APL's work developing miniature devices for spacecraft.

Triggered by cold temperatures or stress, Raynaud's is characterized by numbness and coldness in the fingers, toes, ears and/or nose when blood vessels in those areas constrict during attacks. Insufficient blood flow near the skin's surface also causes patients to experience skin color changes and varying levels of discomfort. Limited blood flow to the extremities can potentially lead to permanent loss of function. Raynaud's can occur on its own, or be secondary to another condition, such as autoimmune disorders like scleroderma or lupus.

"The Ambulatory Raynaud's Monitor is a tiny, Band-Aid-like device that enables physicians to objectively characterize a patient's condition, determine its severity and measure symptoms in real time," said Wigley, who is one of the country's leading sceloderma experts. "Until now, Raynaud's research has been crippled without such a device."

The small, low-cost monitor wraps around a patient's finger and is secured with a bandage or medical tape. It contains two sensors that alternately record skin and ambient temperatures — indicators of surface blood flow — every 36 seconds. Interactive controls permit a patient to record the date and time of a suspected Raynaud's attack. A week's data is held by the monitor's electronics and is retained even if the device's power is unexpectedly interrupted.

Physicians can easily download the data into a computer or PDA, and software developed by APL enables them to quickly and easily display and plot it, a task that can be done during a patient's appointment to provide real-time feedback.

The monitoring system's batteries store enough energy to operate for several months, and devices can be cleaned and reinitialized for use with multiple patients.

The device recently underwent initial testing on patients with Raynaud's being treated at the Johns Hopkins Medical Institutions. Patients wore a monitor for one week in their homes, pressing a button on the device to indicate when a Raynaud's event was occurring. The initial data, processed by APL engineers and evaluated by JHMI physicians, indicates that Raynaud's events can be successfully identified. Patients said the devices are comfortable and easy to use.

Binh Le of APL, one of the inventors of the device, said, "The data from this preliminary study suggests that the monitor can help scientists and physicians learn more about Raynaud's phenomenon and help investigators evaluate the effectiveness of drugs being developed to treat this disease."

Since the initial testing, APL researchers have enhanced the monitor's design and are gearing up for the next round of trials, later this winter.

In addition to monitoring Raynaud's patients, this platform technology could be used for an array of other medical or monitoring applications. The monitor could be modified to measure skin temperature of patients at risk for developing cardiovascular disease by tracking endothelial function (how small blood vessels regulate local blood flow to the tissues). Measuring skin temperature in various real-life situations may provide a noninvasive method to determine vascular responses in health and in various disease states.

With appropriate modifications, the monitoring system also could be used to track other physiological parameters, such as pulse rate and blood pressure, and transmit the information to remote call centers. Athletes, for example, could wear a device to help measure their physiological performance throughout exercise routines.


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