0
Research Papers

Simulation of Airflow in an Idealized Emphysematous Human Acinus

[+] Author and Article Information
Amitvikram Dutta

Mechanical and Mechatronics Engineering,
University of Waterloo,
Waterloo, ON N2 L 3G1, Canada

Dragos M. Vasilescu, James C. Hogg

Center for Heart and Lung Innovation,
University of British Columbia,
Vancouver, BC V6Z 1Y6, Canada

A. B. Phillion

Materials Science and Engineering,
McMaster University,
Hamilton, ON L8S 4L7, Canada

J. R. Brinkerhoff

School of Engineering,
University of British Columbia–Okanagan,
Kelowna, BC V1V 1V7, Canada
e-mail: joshua.brinkerhoff@ubc.ca

1Corresponding author.

Manuscript received June 10, 2017; final manuscript received March 16, 2018; published online April 19, 2018. Assoc. Editor: Ching-Long Lin.

J Biomech Eng 140(7), 071001 (Apr 19, 2018) (10 pages) Paper No: BIO-17-1253; doi: 10.1115/1.4039680 History: Received June 10, 2017; Revised March 16, 2018

Emphysema is the permanent enlargement of air spaces in the respiratory regions of the lung due to destruction of the inter-alveolar septa. The progressive coalescence of alveoli and alveolar ducts into larger airspaces leads to the disruption of normal airway wall motion and airflow rates within the pulmonary acinus. To contribute to the understanding of the individual effects of emphysema during its earliest stages, computational fluid dynamics (CFD) simulations of airflow in mathematically derived models of the pulmonary acinus were performed. The here generated computational domain consists of two generations of alveolar ducts within the pulmonary acinus, with alveolar geometries approximated as closely packed, 14-sided polygons. Physiologically realistic airflow rates and wall motions were used to study airflow patterns within subsequent generations of alveolar ducts during the inspiratory and expiratory phases of the breathing cycle. The effects of progressive emphysema on the airway wall motion and flow rates were simulated by sequentially removing all alveolar septa within each alveolar duct. Parametric studies were presented to independently assess the relative influence of progressive septal destruction of airway motion and flow rates. The results illustrate that septal destruction lowers the flow resistance through the alveolar ducts but has little influence on the mass transport of oxygen into the alveoli. Septal destruction has a net effect on the flow field by favoring the development of recirculatory flow patterns in individual alveoli.

FIGURES IN THIS ARTICLE
<>
Copyright © 2018 by ASME
Your Session has timed out. Please sign back in to continue.

References

Snider, G. L. , Kleinerman, J. , Thurlbeck, W. M. , and Bengali, Z. H. , 1985, “ The Definition of Emphysema,” Am. Rev. Respir. Dis., 132(1), pp. 182–185. [PubMed]
Snider, G. , 1992, “ Emphysema: The First Two Centuries-and Beyond. A Historical Overview, With Suggestions of Future Research—Part 2,” Am. Rev. Respir. Dis., 146(6), pp. 1615–1622. [CrossRef] [PubMed]
American Thoracic Society, 1995, “ Statement on Standards for the Diagnosis and Care of Patients With Chronic Obstructive Pulmonary Disease (COPD) and Asthma,” Am. J. Respir. Crit. Care Med., 152(5), pp. S78–S121.
Thurlbeck, W. M. , and Müller, N. , 1994, “ Emphysema: Definition, Imaging, and Quantification,” AJR. Am. J. Roentgenol., 163(5), pp. 1017–1025. [CrossRef] [PubMed]
West, J. B. , 2005, Pulmonary Pathophysiology: The Essentials, Lippincott Williams and Wilkins, Philadelphia, PA.
Wilkinson, T. M. , Donaldson, G. C. , Hurst, J. R. , Seemungal, T. A. , and Wedzicha, J. A. , 2004, “ Early Therapy Improves Outcomes of Exacerbations of Chronic Obstructive Pulmonary Disease,” Am. J. Respir. Crit. Care Med., 169(12), pp. 1298–1303. [CrossRef] [PubMed]
Vestbo, J. , Hurd, S. S. , Agusti, A. G. , Jones, P. W. , Vogelmeier, C. , Anzueto, A. , Barnes, P. J. , Fabbri, L. M. , Martinez, F. J. , Nishimura, M. , Stockley, R. A. , Sin, D. D. , and Rodriguez-Roisin, R. , 2013, “ Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease: GOLD Executive Summary,” Am. J. Respir. Crit. Care Med., 187(4), pp. 347–365. [CrossRef] [PubMed]
Coultas, D. , Mapel, D. , Gagnon, R. , and Lydick, E. V. A. , 2001, “ The Health Impact of Undiagnosed Airflow Obstruction in a National Sample of United States Adults,” Am. J. Respir. Crit. Care Med., 164(3), pp. 372–377. [CrossRef] [PubMed]
Dailey, H. L. , and Ghadiali, S. , 2007, “ Fluid-Structure Analysis of Microparticle Transport in Deformable Pulmonary Alveoli,” J. Aerosol Sci., 38(3), pp. 269–288. [CrossRef]
Kumar, H. , Tawhai, M. H. , Hoffman, E. A. , and Lin, C. L. , 2009, “ The Effects of Geometry on Airflow in the Acinar Region of the Human Lung,” J. Biomech., 42(11), pp. 1635–1642. [CrossRef] [PubMed]
Hofemeier, P. , and Sznitman, J. , 2014, “ Role of Alveolar Topology on Acinar Flows and Convective Mixing,” ASME J. Biomech. Eng., 136(6), p. 061007. [CrossRef]
Yu, C. P. , and Rajaram, S. , 1978, “ Diffusional Deposition of Particles in a Model Alveolus,” J. Aerosol Sci., 9(6), pp. 521–525. [CrossRef]
Darquenne, C. , and Paiva, M. , 1996, “ Two- and Three-Dimensional Simulations of Aerosol Transport and Deposition in Alveolar Zone of Human Lung,” J. Appl. Physiol., 80(4), pp. 1401–1414. [CrossRef] [PubMed]
Tsuda, A. , Butler, J. P. , and Fredberg, J. J. , 1994, “ Effects of Alveolated Duct Structure on Aerosol Kinetics—II: Gravitational Sedimentation and Inertial Impaction,” J. Appl. Physiol., 76(6), pp. 2510–2516. [CrossRef] [PubMed]
Tsuda, A. , Henry, F. S. , and Butler, J. P. , 1995, “ Chaotic Mixing of Alveolated Duct Flow in Rhythmically Expanding Pulmonary Acinus,” J. Appl. Physiol., 79(3), pp. 1055–1063. [CrossRef] [PubMed]
Weibel, E. R. , Sapoval, B. , and Filoche, M. , 2005, “ Design of Peripheral Airways for Efficient Gas Exchange,” Respir. Physiol. Neurobiol., 148(1–2), pp. 3–21. [CrossRef] [PubMed]
Sapoval, B. , Filoche, M. , and Weibel, E. R. , 2002, “ Smaller is Better but Not Too Small: A Physical Scale for the Design of the Mammalian Pulmonary Acinus,” Proc. Natl. Acad. Sci., 99(16), pp. 10411–10416. [CrossRef]
Sznitman, J. , Heimsch, T. , Wildhaber, J. H. , Tsuda, A. , and Rösgen, T. , 2009, “ Respiratory Flow Phenomena and Gravitational Deposition in a Three-Dimensional Space-Filling Model of the Pulmonary Acinar Tree,” ASME J. Biomech. Eng., 131(3), p. 031010. [CrossRef]
Sznitman, J. , Heimsch, F. , Heimsch, T. , Rusch, D. , and Rösgen, T. , 2007, “ Three-Dimensional Convective Alveolar Flow Induced by Rhythmic Breathing Motion of the Pulmonary Acinus,” ASME J. Biomech. Eng., 129(5), pp. 658–665. [CrossRef]
Hofemeier, P. , Shachar-Berman, L. , Tenenbaum-Katan, J. , Filoche, M. , and Sznitman, J. , 2015, “ Unsteady Diffusional Screening in 3D Pulmonary Acinar Structures: From Infancy to Adulthood,” J. Biomech., 49(11), pp. 2193–2200. [CrossRef] [PubMed]
Oakes, J. M. , Marsden, A. L. , Grandmont, C. , Shadden, S. C. , Darquenne, C. , and Vignon-Clementel, I. E. , 2014, “ Airflow and Particle Deposition Simulations in Health and Emphysema: From In Vivo to In Silico Animal Experiments,” Ann. Biomed. Eng., 42(4), pp. 899–914. [CrossRef] [PubMed]
Aghasafari, P. , Ibrahim, I. B. , and Pidaparti, R. M. , 2016, “ Investigation of the Effects of Emphysema and Influenza on Alveolar Sacs Closure Through CFD Simulation,” J. Biomed. Sci. Eng., 9(6), p. 66601. [CrossRef]
Oakes, J. M. , Hofemeier, P. , Vignon-Clementel, I. E. , and Sznitman, J. , 2015, “ Aerosols in Healthy and Emphysematous In Silico Pulmonary Acinar Rat Models,” J. Biomech., 49(11), pp. 2213–2220. [CrossRef] [PubMed]
Vasilescu, D. M. , Phillion, A. B. , Tanabe, N. , Kinose, D. , Paige, D. F. , Kantrowitz, J. J. , Liu, G. , Liu, H. , Fishbane, N. , Verleden, S. E. , Vanaudenaerde, B. M. , Lenburg, M. , Stevenson, C. S. , Spira, A. , Cooper, J. D. , Hackett, T.-L. , and Hogg, J. C. , 2017, “ Nondestructive Cryomicro-Ct Imaging Enables Structural and Molecular Analysis of Human Lung Tissue,” J. Appl. Physiol., 122(1), pp. 161–169. [CrossRef] [PubMed]
Berg, E. J. , 2011, “ Stereoscopic Particle Image Velocimetry Analysis of Healthy and Emphysemic Acinus Models,” ASME J. Biomech. Eng., 133(6), p. 061004. [CrossRef]
Fung, Y. , 1988, “ A Model of the Lung Structure and Its Validation,” J. Appl. Physiol., 64(5), pp. 2132–2141. [CrossRef] [PubMed]
Sznitman, J. , 2013, “ Respiratory Microflows in the Pulmonary Acinus,” J. Biomech., 46(2), pp. 284–298. [CrossRef] [PubMed]
Patankar, S. , 1980, Numerical Heat Transfer and Fluid Flow, CRC Press, Boca Raton, FL.
Wagner, P. D. , Dantzker, D. R. , Dueck, R. , Clausen, J. L. , and West, J. B. , 1977, “ Ventilation-Perfusion Inequality in Chronic Obstructive Pulmonary Disease,” J. Clin. Invest., 59(2), pp. 203–216. [CrossRef] [PubMed]
Henry, F. S. , Butler, J. P. , and Tsuda, A. , 2002, “ Kinematically Irreversible Acinar Flow: A Departure From Classical Dispersive Aerosol Transport Theories,” J. Appl. Physiol., 92(2), pp. 835–845. [CrossRef] [PubMed]
Hofemeier, P. , Fishler, R. , and Sznitman, J. , 2014, “ The Role of Respiratory Flow Asynchrony on Convective Mixing in the Pulmonary Acinus,” Fluid Dyn. Res., 46(4), p. 041407. [CrossRef]

Figures

Grahic Jump Location
Fig. 1

Computational domain of section of pulmonary acinus for present study: (a) side view and (b) top view. The arrows indicate the direction of airflow through the computational geometry during inspiration (solid arrows) and expiration (dashed arrows), respectively.

Grahic Jump Location
Fig. 2

Progressive destruction of alveolar septa in the computational domain: (a) healthy case, (b) case I, (c) case II, and (d) case III

Grahic Jump Location
Fig. 3

Variation of respiratory flow rate versus lung volume for healthy and COPD-affected lungs. Adapted from West [5].

Grahic Jump Location
Fig. 4

(a) Displacement of the airway wall from rest during inspiration and expiration for the healthy and diseased cases and (b) temporal variation of flow rate into the pulmonary acinus during inspiration and expiration for the healthy and diseased cases

Grahic Jump Location
Fig. 5

Temporal variation of the percentage increase in oxygen concentration within a duct (C¯) for cases with both septal destruction and emphysematous wall motion/inlet flow rates

Grahic Jump Location
Fig. 6

Temporal variation of the percentage increase in oxygen concentration within a duct (C¯) for cases with only emphysematous septal destruction

Grahic Jump Location
Fig. 7

Temporal variation of the percentage increase in oxygen concentration within a duct (C¯) for cases with only emphysematous wall motion/inlet flow rates

Grahic Jump Location
Fig. 8

Temporal variation in the static pressure drop across the alveolar ducts for cases with both septal destruction and emphysematous wall motion/inlet flow rates

Grahic Jump Location
Fig. 9

Temporal variation in the static pressure drop across the alveolar ducts for cases with only emphysematous septal destruction

Grahic Jump Location
Fig. 10

Temporal variation in the static pressure drop across the alveolar ducts for cases with only emphysematous wall motion/inlet flow rates

Grahic Jump Location
Fig. 11

Velocity contours at peak inspiration (a) healthy case, (b) case I, (c) case II, and (d) case III. Arrows indicate general flow direction in the acinus.

Grahic Jump Location
Fig. 12

Velocity contours at peak expiration (a) healthy case, (b) case I, (c) case II, and (d) case III. Arrows indicate general flow direction in the acinus.

Grahic Jump Location
Fig. 13

Streamlines in an individual alveolus from duct 1 near the end of inspiration for the healthy and diseased cases. Streamlines are colored according to velocity magnitude.

Tables

Errata

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In