Wireless Reflux Chip
By Jen
Christensen
Posted: Monday, December
31, 2007 at 7:47 a.m. Gastroesophageal
Reflux
Gastroesophageal reflux is a condition
in which stomach acids back up into the esophagus, the tube that
carries food and liquids from the mouth to the stomach. At the
bottom of the esophagus there is a muscular ring of tissue, called
the lower esophageal sphincter (LES). The LES works like a one-way
valve to allow food to pass into the stomach.
Sometimes the
LES doesn’t close tightly. That allows partially digested food,
liquids and stomach acid to back up into the esophagus (reflux).
When the contents touch the walls of the lining of the esophagus,
they cause a burning sensation in the chest or throat. The symptoms
are commonly called heartburn or acid indigestion.
The
American College of Gastroenterology estimates about 60 million
Americans reflux at least once a month. If the symptoms occur more
than twice a week, they are known as gastroesophageal reflux
disease, or GERD. More than 15 million Americans are believed to
have GERD.
Over time, continued reflux of stomach acids can
damage the lining of the esophagus and lead to bleeding or
development of ulcers or scarring. Patients may experience shortness
of breath, a choking sensation or swallowing problems. In some
cases, the cells lining the esophagus take on the characteristics of
those lining the intestines. This condition is called Barrett’s
Esophagus. People with Barrett’s Esophagus have up to 125 times the
risk of developing esophageal cancer.
pH Monitoring for
GERD
Diagnosis of GERD is often made based on a
patient’s symptoms and positive response to treatment. If the cause
of the symptoms is uncertain, an esophageal pH test may be ordered.
This test measures the pH in the esophagus over 24 to 48 hours. A
thin tube is passed through one of the nostrils and down into the
esophagus. The lower end of the tube contains an acid sensing tip
and sits about two inches above the LES. The middle section of the
tube (where it is inserted into the nose) is secured to the face
with tape. Then the other end is connected to a portable device that
records the pH readings, providing a measure of the frequency and
duration of reflux episodes.
Another type of esophageal pH
test is the Bravo capsule. The capsule is small (about the size of a
gel cap drug) and wireless. It is attached to the wall of the
esophagus through a tube inserted into the throat. For about 48
hours, sensors in the capsule measure the pH levels in the esophagus
and transmit the information to a receiver worn on a belt or
waistband. The capsule falls off and naturally passes through the
digestive tract. The area of attachment heals within five to seven
days.
A New Wireless Monitoring
System
Many people dislike traditional esophageal
pH monitoring because the tube is uncomfortable and conspicuous.
Patients may change their food intake or activities to accommodate
the problems encountered with the tube, providing false results from
the test.
The Bravo capsule overcomes these limitations by
being wireless. However, Shou Jiang Tang, M.D., Gastroenterologist
with UT Southwestern-Dallas, says it still has limits. Not all cases
of GERD are caused by acid reflux. Thus, if non-acidic liquids pass
into the esophagus, the pH reading won’t change and a GERD diagnosis
may be missed.
Fred Tibbals, Ph.D., Bioinstrumentation
Resources Center Director at UT Southwestern-Dallas, is working with
colleagues at UT Arlington to develop a different kind of wireless
esophageal monitoring system. They have combined radiofrequency
identification (RFID) technology with impedance monitoring (a
measure of changes in electrical impulses as foods move through the
esophagus). The two systems are placed on a dime-sized chip that is
pinned to the esophagus. The chip monitors acidic and non-acidic
liquids as they pass through the esophagus. The information is then
transmitted to a wireless sensor worn around the
neck.
Currently, researchers have only tested the wireless
chip on animals. However, these preliminary studies show the device
is significantly better at detecting all causes of reflux than
standard pH monitoring techniques. Human studies still need to be
conducted and the device will need to have FDA approval before it
can be made available.
AUDIENCE INQUIRYFor general information on
GERD, diagnosis or treatment:
American College of
Gastroenterology, http://www.acg.gi.org
National
Institute of Diabetes and Digestive and Kidney Diseases, http://www.niddk.nih.gov
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