Chapter 8 - Exhaled particles

Abstract

Particles in exhaled breath are most likely generated when collapsed small airways reopen during inhalation, a phenomenon sometimes referred to as “surface film disruption” or “fluid film rupture.” Their size is generally smaller than 1μm and their chemical composition is very similar to pulmonary surfactant. While large interindividual differences in particle emission have been described, the intraindividual numbers of exhaled particles are highly reproducible. Therefore, the physical characteristics of droplet emission could potentially provide a “fingerprint” for specific lung diseases. Exhaled breath particles can be collected by impaction or using special filters. The amount of collected particles can be increased by specific breathing maneuvers, but the mass of particles that can be collected within 20min is only in the range of 20–300ng and therefore requires highly sensitive analytical technologies. Nevertheless, exhaled breath particles offer a novel way to investigate undiluted small airway lining fluid in lung disease. This chapter introduces the topic of exhaled particle collection and analysis and reviews notable findings in relation to associated biomarkers.