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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