Exhaled particles and small airways

B. Bake; P. Larsson; G. Ljungkvist; E. Ljungström; A-C Olin

doi:10.1186/s12931-019-0970-9

Respiratory Research (Jan 2019)

Exhaled particles and small airways

B. Bake,
P. Larsson,
G. Ljungkvist,
E. Ljungström,
A-C Olin

Affiliations

B. Bake: Unit of Respiratory Medicine and Allergy, Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg
P. Larsson: Unit of Occupational and Environmental Medicine, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg
G. Ljungkvist: Unit of Occupational and Environmental Medicine, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg
E. Ljungström: Atmospheric Science, Department of Chemistry and Molecular Biology, University of Gothenburg
A-C Olin: Unit of Occupational and Environmental Medicine, Department of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg

DOI: https://doi.org/10.1186/s12931-019-0970-9
Journal volume & issue: Vol. 20, no. 1
pp. 1 – 14

Abstract

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Abstract Background Originally, studies on exhaled droplets explored properties of airborne transmission of infectious diseases. More recently, the interest focuses on properties of exhaled droplets as biomarkers, enabled by the development of technical equipment and methods for chemical analysis. Because exhaled droplets contain nonvolatile substances, particles is the physical designation. This review aims to outline the development in the area of exhaled particles, particularly regarding biomarkers and the connection with small airways, i e airways with an internal diameter < 2 mm. Main body Generation mechanisms, sites of origin, number concentrations of exhaled particles and the content of nonvolatile substances are studied. Exhaled particles range in diameter from 0.01 and 1000 μm depending on generation mechanism and site of origin. Airway reopening is one scientifically substantiated particle generation mechanism. During deep expirations, small airways close and the reopening process produces minute particles. When exhaled, these particles have a diameter of < 4 μm. A size discriminating sampling of particles < 4 μm and determination of the size distribution, allows exhaled particle mass to be estimated. The median mass is represented by particles in the size range of 0.7 to 1.0 μm. Half an hour of repeated deep expirations result in samples in the order of nanogram to microgram. The source of these samples is the respiratory tract ling fluid of small airways and consists of lipids and proteins, similarly to surfactant. Early clinical studies of e g chronic obstructive pulmonary disease and asthma, reported altered particle formation and particle composition. Conclusion The physical properties and content of exhaled particles generated by the airway reopening mechanism offers an exciting noninvasive way to obtain samples from the respiratory tract lining fluid of small airways. The biomarker potential is only at the beginning to be explored.

Published in Respiratory Research

ISSN: 1465-9921 (Print); 1465-993X (Online)
Publisher: BMC
Country of publisher: United Kingdom
LCC subjects: Medicine: Internal medicine: Specialties of internal medicine: Diseases of the respiratory system
Website: https://respiratory-research.biomedcentral.com/

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Abstract

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