A Breath of Fresh Air

Testing for drug use and disease is often complicated – blood and urine samples can be invasive, difficult to collect and easy to tamper with, especially in the field. Unfortunately, there’s no reliable alternative at the moment. But soon there might be: your breath.

The sampling of particles in exhaled breath is noninvasive, relatively easy to perform, and can be supervised to avoid tampering. However, it is still a new methodology in need of further research, which is why researchers at the University of Gothenburg, Sweden, decided to investigate two different sampling principles (1). The first is the PExA method, which is based on impaction and is designed to collect 0.5–7 μm particles from the small airways. The second method is based on filtration and collects particles of all sizes, including those formed during exhalation in the central or upper airways and oral cavity. Lead author Göran Ljungkvist explains…

“The more specific PExA method was originally designed for the collection of disease biomarkers. Using exhaled breath for that task poses an interesting analytical challenge: the limited amount of sample (on the order of 100 ng). In our research group, we analyze some of the important constituents of the lining fluid of the airways – for instance, surfactant protein A and the major surfactant lipids. PExA isn’t just limited to those molecules, though; it can be used to explore many other possible markers of disease. And because it’s noninvasive and easy for the patient (unlike bronchoalveolar lavage or induced sputum), the sampling can be performed repeatedly to monitor disease status, medication efficacy, or treatment compliance. PExA also allows us, for the first time, to sample disease markers from the active site in small airway diseases – facilitating screening and early detection.

“The PExA instrument is already commercially available and used by research groups all over the world. Our next steps? First, we need to validate biomarkers of the disease of interest. Then, ideally, we’d like to make the analytical testing either sensor-based or performed by something cheaper and less complex than, for instance, a mass spectrometer. Finally, we’d also like to miniaturize the sampler. The timeline for these steps is difficult to predict – it will depend on the disease of interest and the validation of the biomarker. The most exciting part? The ability to perform research on exhaled particles opens up a new range of possibilities for diagnostics and monitoring – initially of airway diseases, but eventually perhaps many others as well.”