Electronic Nose Detects Pneumonia in Critically Ill
PA) According to a team of researchers from University
of Pennsylvania School of Medicine, an electronic
nose - a relatively new version of a sensor previously
used in the food, wine and perfume industries - can
quickly and accurately diagnose pneumonia in critically
ill, mechanically ventilated patients. The results will
be presented at the CHEST 2002 Annual Meeting Tuesday,
November 5th in San Diego.
"We wanted to further explore using the e-nose
after the exciting results of an initial study we conducted
back in 1997 with only 20 patients," said C.
William Hanson, III, MD, professor of Anesthesia,
Surgery and Internal Medicine, and lead author of the
study. When it comes to lower pulmonary infections,
especially in critically ill patients, time is of the
essence for disease control. "Rather than waiting
two to three days for the results of a bacterial culture
or relying on chest X-rays which aren't always accurate,
the e-nose can give us a head start toward a proper
diagnoses. We could avoid over-prescribing powerful
antibiotics which are usually given to patients while
we're waiting for their test results, even though we
don't know if they actually need them," adds Hanson.
In the current study, 415 mechanically ventilated, critical
care patients were screened for the presence of ventilator
associated pneumonia (VAP) using a clinical pneumonia
score (CPIS). Patients with high CPIS scores were enrolled
in the study as well as control patients who had no
evidence of pneumonia. An exhaled breath sample was
taken from each patient directly from the expiratory
limb of the ventilator circuit into an electronic nose
made by Cyrano Sciences, Pasadena, CA. This differs
from the original study where breath samples were collected
in plastic bags from the ventilators of intubated intensive
care patients and then fed into a different electronic
The e-nose contains an array of sensors consisting of
carbon-black/polymer composites. The patient's exhaled
breath gas was passed over these sensors which interact
with volatile molecules to produce unique patterns that
are displayed in two-dimensional "maps," or
dot patterns on a computer screen. The results were
analyzed using pattern recognition algorithms and assessed
for a correlation between the actual CPIS scores and
the one predicted by the nose. Hanson and his colleagues
found that the nose made clear distinctions between
the patients who were infected and those who were not.
"The data show good correlation between the actual
scores and those predicted by the data from the e-nose
sensor," said Hanson. "Furthermore, this study
suggests that the commercial electronic nose, as is,
would be reasonably successful in predicting ventilator
associated pneumonia. It would be even more suited to
the task if the sensor array could be customized."
Preliminary data also suggests that the e-nose may be
able to distinguish between pneumonias caused by different
Cyrano Sciences, Inc., donated a "Cyranose"
electronic nose for use in this study.
# # #
Editor's Note: Dr. Hanson does not have
any financial ties with Cyrano Sciences, Inc., and will
be available at the CHEST 2002 Annual Meeting and by
phone for comment.
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