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| Advantages With the Heliprobe System |
The use of 14C-urea breath
to detect Helicobacter pylori infection is common, but the products
used have been developed within the academic world and have
not been registered for such use within Europe. There are two
13C-urea breath tests registered within the EU (Pylobactell;
Helicobacter Test INFAI), but this is the first 14C-urea
product. A 14C-urea breath test, called PYTest is
marketed in the USA.
The Heliprobe (Urea Breath Test) is a device that quickly, inexpensively
and accurately detects whether a patient has Helicobacter pylori
in his/her gastrointestinal tract. The Heliprobe System is composed
of the HeliprobeTM Analyzer a BreathCardTM
(credit card size breath collector) and a HeliCapTM
(14C Urea Capsule).
The BreathCardTM, the shape and size of a credit
card, contains two pads soaked in lithium hydroxide. When the
patient breathes into the mouthpiece, both pads are exposed
to the exhaled air. Exhaled carbon dioxide to form lithium carbonate,
fixing the carbon atoms in the pads. A pH sensitive indicator
mounted in the card changes colour from orange to yellow to
indicate when the pads are saturated with carbon dioxide. Breathing
time required varies depending on frequencies of breaths in
the card, but averages 1-2 minutes. Once used, the BreathCard
is stable and sturdy; it can be shipped to another location
for reading, stored, or disposed of without special precautions
due to the low radioactivity involved.
The HeliProbeTM analysed contains two shielded Geiger-M?ller
counters mounted in parallel face-to-face. An opening in the
shield allows insertion of the BreathCard between the two counters.
When the BreathCard is fully inserted the pads are perfectly
lined up with the two counters. Correct position of the BreathCard
is verified with an optical sensor and the analysis sequence
can only be initiated if the card is properly inserted. |
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Microprocessor controlled electronics
in the analyzer steer the measurements cycle, keeping continuous
tract of and compensating for variations in background radiation
not blocked by the shielding around the Geiger-M?ller counters;
comparing the result with programmed cut-off levels for determination
of disease; and calculating and presenting the result on an
LCD display. A set-up interface allows the user to customize
the most important performance parameters such as the cut-off
level for determination of disease. A thermal printer can be
connected to the HeliProbe Analyzer to print the result.
The HeliCapTM is a hard capsule containing 1 µCi
14C-labeled urea and citric acid. The capsule is
swallowed intact and its content is released in the stomach
thereby assuring that urea will not be exposed to mouth bacteria
which poses a risk for false positive results. The purpose of
the citric acid is to add acidity in the stomach which firstly
eliminates the need for a test meal, and secondly increases
the metabolic process where CO2 is produced thereby
the accuracy of the test.
The test procedure is simple: 10 minutes after swallowing the
HeliCap, the patient exhales through the BreathCard until it
is fully saturated. The BreathCard is inserted into the analysis
unit and a one-button operation starts the analysis. The result
is presented 250 seconds later as “infected”, “not
infected”, or “borderline”, together with
a quantitative assessment of the degree of infection.
Other 14C-urea and 13C-urea breath test
analysis units are expensive and difficult to run. The urea
is taken in liquid form increasing the risk for false positive
results if the mouth hygiene is compromised. A test meal or
a separate citric acid drink must be administrated with the
urea. Test sampling and analysis requires laboratory expertise.
These properties make the other urea breath tests less suited
for small clinics, unless the doctor is prepared to send samples
in the mail, wait several days for the test result and recall
the patient for a second consultation.
The most important advantages with the HeliProbe system are
speed and ease of use. Without external facilities or expertise,
the doctor has access to the test result 15-20 minutes after
the patient has swallowed the 14C-urea capsule, eliminating
the need for a second consultation. Furthermore, the cost of
the HeliProbe unit is a fraction of that of a traditional breath
test analysis unit. Eliminating the need for a large up-front
investment, together with the time the hospital staff saves
on the simplified test and analysis procedure, makes this system
highly cost effective compared to traditional urea breath tests.
The HeliProbe system will make it easier for smaller gastroenter-ological
clinics and for general practitioners to adopt the highly accurate
urea breath test when diagnosing H pylori. The system combines
the convenience of serological near-patient test systems with
the accuracy of the urea breath test. |
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