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October 4, 2005

Space Technology Benefits Medical Community

A small group of APL researchers, in collaboration with physicians from the Hopkins Scleroderma Center, have developed and recently patented a miniature device to help physicians characterize Raynaud's disease and measure treatment effectiveness.

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 scleroderma or lupus.

After reading an APL Technical Digest article about the Laboratory's work developing miniature devices for spacecraft, Dr. Fredrick Wigley, director of the Hopkins Scleroderma Center and one of the country's leading scleroderma experts, asked the Space Department's Paul Schwartz and Binh Le to develop an Ambulatory Raynaud's Monitor (ARM). "This tiny, Band-Aid-like device allows us to objectively characterize a patient's condition, determine its severity, and measure symptoms in real time," Wigley says. "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. The ARM 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 worth of data is held by the monitor's electronics and is retained even if the device's power is unexpectedly interrupted.

Physicians can easily download data into a PC or PDA (personal digital assistant). Software developed by M. Jenkins and David Stott, of the Space Department, allows a physician to quickly and easily display and plot data, which could be done during a patient's appointment to provide real-time feedback. The ARM's batteries store enough energy to operate for several months, and devices can be cleaned and reinitialized for use with multiple patients.

Schwartz and Le designed the device to be low-cost, small, and comfortable enough so patients would be encouraged to wear it. Some previous prototype monitors were bulky, with wires running from a device on a patient's finger to a large recording device worn on a patient's belt, according to Wigley. "It was no surprise patients didn't like wearing these earlier prototypes," he says.

Currently, to determine the effectiveness of a particular treatment or gauge the disease's effect on a patient, doctors either ask them a series of questions or bring them into an artificial laboratory setting, says Wigley. "Information gained from either of these methods isn't as accurate or realistic as having someone wear this device in their normal daily environment with data automatically recorded."

Other Applications

According to Schwartz and Le, future ARM designs could include a skin conductivity sensor to measure stress, another Raynaud's trigger.

If the devices can be made even smaller, Wigley envisions acquiring 3-D views of a patient's attack by placing monitors on different parts of the body and sending signals to a larger, cell-phone-sized device attached to a patient's belt.

The device could be used for an array of other medical, military, or recreational applications. Soldiers could wear the device to help doctors remotely determine the level of an injury experienced in the field. Athletes could wear it to help determine when they're approaching heat exhaustion.

Schwartz and Le are working on the next-generation prototype and preparing a small number of units, being built by the Technical Services Department, for field trials this winter. They're also working with APL's Office of Technology Transfer to potentially license this invention.

"It's very rewarding to work on a project like this that can potentially benefit so many people," Schwartz says. For more information about the Ambulatory Raynaud's Monitor, contact Schwartz, at 443-778-8884, or Le, at ext. 443-778-4711.