Breath-smelling computers trace bacterial lung diseases in no time

Philadelphia 08 October 1999At the Imperial College in London, the Breathalyzer is currently being developed, a device to detect the bacterial odour of diseases. The patient has to breathe through a tube, connected to a reaction chamber with an integrated sensor to measure very low molecular concentrations. Traces of certain chemicals may indicate the presence of infectious bacteria. Doctors are able to use the method to distinguish between diseases which can be caused by bacterial as well as viral infection. If the bacterial odour is missing, the patient's complaints are due to a viral infection. In that case, the prescription of antibiotics is unneeded. The Imperial College however is not the first to discover the possibilities of this type of electronic nose. The Pennsylvanian team of Dr. Hanson already used a similar tool earlier on, to detect pneumonia in hospitalised patients.


A few years ago, researchers at the University of Pennsylvania, have developed technology to diagnose lung infections with an electronic sniffer. Cats, dogs, and other animals depend on their noses for survival, so why not try to find a more significant medical use for the sense of smell for humans? This is the rationale behind the research conducted by Dr. C. William Hanson III, M.D., associate professor of anaesthesia and chief of anaesthesia/critical care medicine at the University of Pennsylvania Medical Center. The novel electronic "nose" is utilised to diagnose the presence of pulmonary infection.

According to Dr. Hanson, diagnosing diseases from the smell of a patient's breath stretches back to the dawn of medicine. For example, Roman doctors coined the term "Fetor Hepaticus" for the distinctive breath of patients suffering kidney failure, while patients with out-of-control diabetes have an unmistakable "juicy fruit" breath. Dr. Hanson claims it's conceivable that electronic noses may eventually screen patients for a range of lung and intestinal ailments, like pneumonia, advanced diabetes, and kidney and liver failure, as well as skin conditions, such as cancers and ulcers.

The electronic nose detects pneumonia in intensive care patients. Whereas the traditional tests for pneumonia take a couple of days, the device provides immediate feedback. The e-nose has the potential to save lives and prevent doctors from prescribing broad-spectrum antibiotics which can lead to drug-resistant bugs, as Dr. Hanson explains. The computerised nose in essence is an aroma-analysis device used widely in the beverage, food, and perfume industries. The Hanson team has identified a new way to utilise the device's unique 32-sensor array in the field of medicine. The e-nose diagnoses can be carried out at a fraction of the cost of conventional diagnostic techniques.

Breath samples have been collected in plastic bags from the ventilators of 19 intensive care patients. Nine were already diagnosed with pneumonia. The samples have been fed into the aroma-analysis device. The exhaled gas has been analysed with the device's multi-element odour detectors which interact with volatile molecules to produce unique patterns displayed in 2D maps or dot patterns, on a computer screen. The e-nose displays a varying electrical resistance to the breath sample's volatile molecules by plotting distinctively different patterns on the screen, in order to distinguish the infected patients from the non-infected ones.

The use of the electronic "nose" has several major advantages over conventional diagnostic tools and has great potential as a method to detect other diseases, as well as pulmonary infections. Rather than waiting two to three days for the results of a bacterial culture, or relying on chest X-rays which may be inaccurate, doctors can almost instantaneously evaluate their patients for infection, according to Dr. Hanson. The sense of smell has long been used as a diagnostic tool by medical professionals. Because of its subjectivity however, it has never gained prominence in medicine, until now.

Coupled with current computer technology, innovative use of breath samples has produced the ability to detect infection faster, easier, and at a far earlier stage, with the potential for future applications in the diagnoses of a variety of diseases. Dr. Hanson believes that in 10 or 15 years, patients may be able to walk into a doctor's office and breathe into a machine to be tested for a number of conditions. More news on a similar device, developed at Cranfield University, to track down Urinary Tract Infections is available in this issue's VMW article Computerised nose imitates ancient Chinese sense for scents to diagnose infections.

Leslie Versweyveld

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