Penn researchers show effectiveness of device in analyzing gases exhaled from the nose to determine presence of common bacterial infections
(Philadelphia, PA) – Researchers at the University of Pennsylvania School of Medicine have recently completed three studies – the most comprehensive and largest to date – that demonstrate the effectiveness of an electronic nose device for diagnosing common respiratory infections, specifically pneumonia and sinusitis. Doctors hope that the device – called the Cyranose 320, or e-nose – will provide a faster, more cost-effective and easier-to-use method for accurately diagnosing pneumonia and, as a result, help reduce over-prescription of antibiotics. Their initial findings will be presented at the combined annual meetings of otorhinolaryngology (ear, nose and throat) experts – the Triologic Society and the American Broncho-Esophagological Association – on April 30th, 2004, in Phoenix, Arizona.
"Pneumonia is a serious bacterial infection that can cause serious injury or even death; indeed, it remains a leading cause of death in intensive care units (ICUs)," said lead author of the first study, C. William Hanson III, MD, Professor of Anesthesia and board-certified expert in critical care medicine. "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 first two studies looked at pneumonia cases among patients who are on ventilators in the surgical intensive care unit (SICU). Here, diagnosis is made difficult by the patients' limited ability to move, and they are vulnerable to infections from other compounding injuries. In the first study, researchers found that the e-nose effectively diagnosed 92 percent of pneumonia cases among 25 patients, as confirmed by computed tomography (CT) scans of the lungs. It successfully distinguished 13 positive cases from 12 other patients who did not have pneumonia. Similarly, in the second study, researchers found the e-nose effective in providing accurate diagnoses of pneumonia in 31 of 44 SICU patients (70 percent).
One quarter of ventilated SICU patients develop pneumonia – a serious complication that can threaten the patient's life, requires immediate treatment with antibiotics, and also increases their hospital stay three-fold, with average additional hospital costs of $11,000 per patient.
The third study looked at sinusitis, the most common diagnosis from respiratory complaints by patients in outpatient clinics. The e-nose was effective at diagnosing 82 percent of sinusitis cases among 22 patients, one half infected and the other half not so.
All bacteria, as living organisms, produce unique arrays or mixtures of exhaled gases. The e-nose works by comparing "smellprints" from a patient's breath sample to standardized, or known, readings stored on a computer chip. These "smellprints" are created from both electro-chemical and mathematical analysis of exhaled gases contained in a breath sample. Upon analysis, identifiable patterns emerge, and a patient's "smellprint" can tell a physician whether or not bacteria are present and, if so, what kind. This can aid not just in the accuracy of diagnosis, but can also help physicians select the most effective antibiotic for treatment.
"The results confirm that exhaled breath can be analyzed for pneumonia and sinusitis using a commercially available e-nose device," said lead investigator for the sinusitis study and co-investigator for the pneumonia studies, Erica Thaler, MD, an Associate Professor of Otorhinolaryngology: Head and Neck Surgery at Penn. "There is 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. And, given that we can apply this sensory analysis to the detection of pneumonia and sinusitis, then, hopefully, it can be applied to common bacterial infections of the upper respiratory tract."
The e-nose is also being studied for its possible use in diagnosing many other illnesses, including: lung cancer, kidney disease and cirrhosis of the liver, otitis media (middle ear infections) in children, or even detection of chemicals and biological agents. Manufactured by Smiths Detection of Pasadena, CA, the machines cost approximately $8,000 USD, and still require approval from the federal Food and Drug Administration before they can be widely used. Breath samples are taken with a hand-held sensor – about the size of child's video game player – connected to a standard oxygen mask with cup, as the patient breathes normally. Readings are displayed by connecting the device to a laptop computer.
"Flexibility and ease-of-use are the greatest advantages of the e-nose," said lead researcher Neil Hockstein, MD, a clinical instructor and Penn otorhinolaryngologist. "They are miniaturized devices, provide quick results, are relatively inexpensive, non-invasive, safe for patients and they could be used in a doctor's office – or, potentially, even at home."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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