Scientists show that a person’s breath can be used to detect various diseases including asthma and diabetesScientists in the UK and US – in two separate studies – have shown that various diseases such as diabetes, asthma and cancer can be detected by merely checking a person’s breath.
The researchers at UK’s Swansea University – for their part – are using “GCMS-TD” (gas chromatography, mass spectrometry and thermal desorption) technology to analyse the concentrations of “Volatile Organic Compounds” (VOCs) in breath.
Whereas the team of US scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado (CU), have shown that by sampling a person’s breath using “optical frequency comb spectroscopy” they can detect molecules in the breath that may be markers for diseases.
HOW THE TECHNOLOGY WORKS
Every time we breathe in, we inhale a mixture of gasses – mostly nitrogen, oxygen, carbon dioxide, and water vapour, but also traces of other gasses, such as carbon monoxide, nitrous oxide, etc.
Each time we exhale, we blow out a slightly different mixture with less oxygen, more carbon dioxide, and a rich collection of more than a thousand types of other molecules – most of which are present only in trace amounts.
Some of these tracer breath molecules are biomarkers of disease. Just as bad breath may indicate dental problems, excess methylamine can be used to detect liver and kidney disease, ammonia on the breath may be a sign of renal failure or hepatitis, elevated acetone levels in the breath can indicate diabetes, dimethyl sulphide is linked to cirrhosis, and nitric oxide levels can be used to diagnose asthma.
When many breath molecules are detected simultaneously, highly reliable and diseasespecific information can be collected.
RESEARCH IN THE UNITED KINGDOM…
“Studies have shown that high concentrations of certain VOCs in breath can correlate with disease,” said Dr Masood Yousef, a senior research assistant at Swansea. “If unique markers for diseases can be recognised earlier than traditional techniques, then there is a potential to diagnose disease before any symptoms have developed, and without the need for invasive procedures.”
The GCMS-TD system works by analysing all the chemicals and compounds that make up a patient’s breath. It creates a breath profile, which allows scientists to identify VOCs that may signify the presence of disease.
Dr Yousef believes that the breath test will provide a more convenient method for diagnosing serious diseases than blood or urine analysis.
It is hoped that the research in Swansea will lead to the development of diagnostic tools such as test strips that give positive results for specific illness markers.
... AND IN THE UNITED STATES
While many studies have been done to showcase the potential of optical technologies for breath analysis, the JILA approach takes an important step toward demonstrating the full power of optics for this prospective medical application.
“Our technique – called cavity-enhanced direct optical frequency comb spectroscopy – can give a broad picture of many different molecules in the breath all at once,” said research leader Jun Ye, a fellow of JILA, NIST and a professor at Colorado University’s Department of Physics.
“Optical comb spectroscopy is powerful enough to sort through all the molecules in human breath,” Ye said, “but it is also sensitive enough to find those rarest molecules that may be markers of specific diseases.”
In the experiments performed by Ye and his colleagues, the technique was used to analyse the breath of several student volunteers.
The researchers had the students breathe into an optical cavity – a space between two standing mirrors. The optical cavity was designed so that when they aimed a pulsed laser light into it, the light bounced back and forth so many times that it covered a distance of several kilometres by the time it exited the cavity. This essentially allowed the light to sample the entire volume of the cavity, striking all the molecules therein.
In addition, this lengthens the light-molecule interaction time thereby increasing the sensitivity.
By comparing the light coming out of the cavity to the light that went in, Ye and his colleagues could determine which frequencies of light were absorbed and by how much. This information allows them to sensitively identify many different molecules.
FROM LABS TO DISPENSARIES
While the efficacy of these techniques has yet to be evaluated in clinical trials, monitoring the breath for such biomarkers is an attractive approach to medicine because breath analysis is the ultimate non-invasive and low-cost procedure.
“Breath samples are much easier to collect than blood and urine,” Dr Yousef said. “They can be collected anywhere by people with no medical training, and there are no associated biohazard risks.”
