Police dogs hot on the chase,
sniffing out the bad guys is a pretty standard scene out
of any cop show. Having physicians do the same to detect
disease sounds a little like a bad sci-fi flick. Nonetheless,
that's just what the Cyranose 320 may let docs do. This
electronic nose is capable of recognizing bacteria by
sampling a patient's breath. It's a hand-held machine
that costs about $10,000 Cdn, which has been fitted by
University of Pennsylvania researchers with a smart chip
capable of learning the chemical 'smellprints' of different
kinds of bacteria. In fact, this nifty little invention
has already demonstrated its ability to successfully diagnose
pneumonia.
Results of trials to test the device
were presented to the combined annual meetings of the
Triologic Society and the American Broncho-Esophagolog-ical
Association in Phoenix. In the first study, it successfully
diagnosed 92% of pneumonia cases in 25 patients. This
trial tested for specificity as well as sensitivity,
since 12 of the patients were pneumonia-free controls.
In a second trial, the Cyranose
made the correct diagnosis of pneumonia 70% of the time.
A further study examined the e-nose's potential for
diagnosing sinusitis -- the most common respiratory
complaint in US outpatient clinics. In that trial, the
nose was 82% accurate in distinguishing between 11 patients
with sinusitis and 11 uninfected patients.
"The results confirm that exhaled
breath can be analyzed for pneumonia and sinusitis using
a commercially available e-nose device," said Dr Erica
Thaler lead investigator for the sinusitis study. "There's
the potential with this device to radically change and
improve the way we diagnose and treat both conditions
-- for which there is no gold-standard test."
The pneumonia studies involved
patients on ventilation in surgical intensive care units
(ICUs). No less than one-quarter of such patients develop
pneumonia, according to the researchers, and the average
cost per patient, at $11,000 US, is higher than the
cost of the e-nose.
"Pneumonia is a serious bacterial
infection that can cause serious injury or even death,"
said the lead researcher in the first study, Dr C William
Hanson III. "Treating this illness is complicated because
there are many kinds of pneumonia, and it can be commonly
misdiagnosed in the ICU and confused with other diseases
which cannot be treated using antibiotics. This is a
leading cause of the overuse -- through over-prescription
-- of antibiotics for false cases of pneumonia."
The researchers argue that while
their device does not yet meet the standards of specificity
and sensitivity achieved by some diagnostic tests, in
the context of pneumonia its results may be as good
as more invasive existing techniques. It also allows
patients on ventilation to be safely tested without
having to leave the ICU for a CT scan.
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