Chaotic Mixing Deep in the Lung

Our current understanding of the transport and deposition of aerosols (viruses, bacteria, air pollutants, aerosolized drugs) deep in the lung has been grounded in dispersive theories based on untested assumptions about the nature of acinar airflow fields. Traditionally, these have been taken to be s...

Full description

Saved in:
Bibliographic Details
Published inProceedings of the National Academy of Sciences - PNAS Vol. 99; no. 15; pp. 10173 - 10178
Main Authors Tsuda, Akira, Rogers, Rick A., Hydon, Peter E., Butler, James P.
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 23.07.2002
National Acad Sciences
The National Academy of Sciences
Subjects
Aerosols
Animals
Biological Sciences
Breathing
Convection
Flow distribution
Fluids
Fractals
In Vitro Techniques
Kinematics
Kinetics
Lung - cytology
Lung - physiology
Lungs
Models, Biological
Nonlinear Dynamics
Pulmonary alveoli
Pulmonary Alveoli - physiology
Rats
Rats, Sprague-Dawley
Respiration, Artificial
Respiratory system
Time Factors
Trachea
Online AccessGet full text

Cover

More Information
Summary:Our current understanding of the transport and deposition of aerosols (viruses, bacteria, air pollutants, aerosolized drugs) deep in the lung has been grounded in dispersive theories based on untested assumptions about the nature of acinar airflow fields. Traditionally, these have been taken to be simple and kinematically reversible. In this article, we apply the recently discovered fluid mechanical phenomenon of irreversible low-Reynolds number flow to the lung. We demonstrate, through flow visualization studies in rhythmically ventilated rat lungs, that such a foundation is false, and that chaotic mixing may be key to aerosol transport. We found substantial alveolar flow irreversibility with stretched and folded fractal patterns, which lead to a sudden increase in mixing. These findings support our theory that chaotic alveolar flow-characterized by stagnation saddle points associated with alveolar vortices-governs gas kinematics in the lung periphery, and hence the transport, mixing, and ultimately the deposition of fine aerosols. This mechanism calls for a rethinking of the relationship of exposure and deposition of fine inhaled particles.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
Communicated by Ewald R. Weibel, University of Bern, Bern, Switzerland
To whom reprint requests should be addressed. E-mail: atsuda@hsph.harvard.edu.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.102318299