Assessing changes in airflow and energy loss in a progressive tracheal compression before and after surgical correction
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
The energy needed to drive airflow through the trachea normally constitutes a minor component of the work of
breathing. However, with progressive tracheal compression, patient subjective symptoms can include severe breathing
difficulties. Many patients suffer multiple respiratory co-morbidities and so it is important to assess compression effects
when evaluating the need for surgery. This work describes the use of computational prediction to determine airflow
resistance in compressed tracheal geometries reconstructed from a series of CT scans. Using energy flux analysis, the
regions that contribute the most to airway resistance during inhalation are identified. The principal such region is where flow
emerging from the zone of maximum constriction undergoes breakup and turbulent mixing. Secondary regions are also
found below the tongue base and around the glottis, with overall airway resistance scaling nearly quadratically with flow
rate. Since the anatomical extent of the imaged airway varied between scans - as commonly occurs with clinical data and
when assessing reported differences between research studies - the effect of sub-glottic inflow truncation is considered.
Analysis shows truncation alters the location of jet breakup and weakly influences the pattern of pressure recovery. Tests
also show that placing a simple artificial glottis in the inflow to a truncated model can replicate patterns of energy loss in
more extensive models, suggesting a means to assess sensitivity to domain truncation in tracheal airflow simulations.
breathing. However, with progressive tracheal compression, patient subjective symptoms can include severe breathing
difficulties. Many patients suffer multiple respiratory co-morbidities and so it is important to assess compression effects
when evaluating the need for surgery. This work describes the use of computational prediction to determine airflow
resistance in compressed tracheal geometries reconstructed from a series of CT scans. Using energy flux analysis, the
regions that contribute the most to airway resistance during inhalation are identified. The principal such region is where flow
emerging from the zone of maximum constriction undergoes breakup and turbulent mixing. Secondary regions are also
found below the tongue base and around the glottis, with overall airway resistance scaling nearly quadratically with flow
rate. Since the anatomical extent of the imaged airway varied between scans - as commonly occurs with clinical data and
when assessing reported differences between research studies - the effect of sub-glottic inflow truncation is considered.
Analysis shows truncation alters the location of jet breakup and weakly influences the pattern of pressure recovery. Tests
also show that placing a simple artificial glottis in the inflow to a truncated model can replicate patterns of energy loss in
more extensive models, suggesting a means to assess sensitivity to domain truncation in tracheal airflow simulations.
Date Issued
2019-12-02
Date Acceptance
2019-11-09
Citation
Annals of Biomedical Engineering, 2019, 48, pp.822-833
ISSN
0090-6964
Publisher
Springer (part of Springer Nature)
Start Page
822
End Page
833
Journal / Book Title
Annals of Biomedical Engineering
Volume
48
Copyright Statement
© 2019 The Author(s). This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/),
which permits unrestricted use, distribution, and
reproduction in any medium, provided you give
appropriate credit to the original author(s) and the
source, provide a link to the Creative Commons
license, and indicate if changes were made.
Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/),
which permits unrestricted use, distribution, and
reproduction in any medium, provided you give
appropriate credit to the original author(s) and the
source, provide a link to the Creative Commons
license, and indicate if changes were made.
Sponsor
Biotechnology and Biological Sciences Research Council (BBSRC)
Engineering & Physical Science Research Council (EPSRC)
Identifier
https://link.springer.com/article/10.1007%2Fs10439-019-02410-1
Grant Number
BB/E023444/1
N/A
Subjects
Science & Technology
Technology
Engineering, Biomedical
Engineering
Tracheal Airflow
Flow Energy Loss
Airway Resistance
Compressed Trachea
Inflow Truncation
Airway CFD
COMPUTATIONAL FLUID-DYNAMICS
LARGE-EDDY SIMULATION
LARYNGEAL JET
SURGERY
MECHANISMS
CHALLENGES
TURBULENCE
PRESSURE
AIRWAYS
FIELD
Airway CFD
Airway Resistance
Compressed Trachea
Flow Energy Loss
Inflow Truncation
Tracheal Airflow
09 Engineering
11 Medical and Health Sciences
Biomedical Engineering
Publication Status
Published
Date Publish Online
2019-12-02