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Contributions of Kinetic Energy and Viscous Dissipation to Airway Resistance in Pulmonary Inspiratory and Expiratory Airflows in Successive Symmetric Airway Models With Various Bifurcation Angles.

ABSTRACT: The aim of this study was to investigate and quantify contributions of kinetic energy and viscous dissipation to airway resistance during inspiration and expiration at various flow rates in airway models of different bifurcation angles. We employed symmetric airway models up to the 20th generation with the following five different bifurcation angles at a tracheal flow rate of 20?L/min: 15?deg, 25?deg, 35?deg, 45?deg, and 55?deg. Thus, a total of ten computational fluid dynamics (CFD) simulations for both inspiration and expiration were conducted. Furthermore, we performed additional four simulations with tracheal flow rate values of 10 and 40?L/min for a bifurcation angle of 35?deg to study the effect of flow rate on inspiration and expiration. Using an energy balance equation, we quantified contributions of the pressure drop associated with kinetic energy and viscous dissipation. Kinetic energy was found to be a key variable that explained the differences in airway resistance on inspiration and expiration. The total pressure drop and airway resistance were larger during expiration than inspiration, whereas wall shear stress and viscous dissipation were larger during inspiration than expiration. The dimensional analysis demonstrated that the coefficients of kinetic energy and viscous dissipation were strongly correlated with generation number. In addition, the viscous dissipation coefficient was significantly correlated with bifurcation angle and tracheal flow rate. We performed multiple linear regressions to determine the coefficients of kinetic energy and viscous dissipation, which could be utilized to better estimate the pressure drop in broader ranges of successive bifurcation structures.

SUBMITTER: Choi S

PROVIDER: S-EPMC5816247 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Contributions of Kinetic Energy and Viscous Dissipation to Airway Resistance in Pulmonary Inspiratory and Expiratory Airflows in Successive Symmetric Airway Models With Various Bifurcation Angles.

Choi Sanghun S Choi Jiwoong J Lin Ching-Long CL

Journal of biomechanical engineering 20180101 1

The aim of this study was to investigate and quantify contributions of kinetic energy and viscous dissipation to airway resistance during inspiration and expiration at various flow rates in airway models of different bifurcation angles. We employed symmetric airway models up to the 20th generation with the following five different bifurcation angles at a tracheal flow rate of 20 L/min: 15 deg, 25 deg, 35 deg, 45 deg, and 55 deg. Thus, a total of ten computational fluid dynamics (CFD) simulations ...[more]

PMID: 29049545

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Project description:PurposeTo establish a method for quantitatively estimating the extent of the communication between the cyst and the airway in cystic lung diseases (CLDs) and evaluate its diagnostic utility in differentiating among CLDs.Materials and methodsSeventy-one patients (mean age, 49.9 years; age range, 25-79 years) with CLDs who underwent paired inspiratory and expiratory CT between July 2015 and July 2018 were enrolled in this prospective study. Participants were divided into three groups based on their diagnosis: Birt-Hogg-Dubé syndrome (BHDS) group (15 participants), lymphangioleiomyomatosis (LAM) group (43 participants), and other diseases (OT) group (13 participants). Total lung volume (TLV) and low-attenuation area volume (LAAV) were calculated at inspiration and expiration. The collapsibility of the LAAV was determined as the expiration-to-inspiration (E/I) ratio of LAAV (E/I ratio LAAV). The cyst-airway communicating index (CACI), the ratio of the LAAV change between inspiration and expiration to the TLV change between inspiration and expiration, was also determined. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic utility for differentiating diseases.ResultsThe E/I ratio LAAV was significantly higher in the BHDS group (0.69; 95% confidence interval [CI]: 0.61, 0.78) than in the LAM (0.33; 95% CI: 0.28, 0.38) (P < .001) and the OT (0.51; 95% CI: 0.38, 0.64) (P = .038) groups. The CACI was significantly lower in the BHDS group (0.89; 95% CI: 0.61, 1.17) than in the LAM (1.89; 95% CI: 1.76, 2.0) (P < .001) and the OT (1.539; 95% CI: 1.21, 1.86) (P = .003) groups. There was no significant difference in the area under the ROC curve of the CACI (0.881; 95% CI: 0.7749, 0.987) and the E/I ratio LAAV (0.877; 95% CI: 0.791, 0.963) for differentiating BHDS from other diseases.ConclusionQuantitative analysis using paired inspiratory and expiratory CT for estimating the extent of cyst-airway communication in CLDs is useful when distinguishing BHDS from other diseases.Supplemental material is available for this article.© RSNA, 2020See also the commentary by Chung in this issue.

Dataset Information

Contributions of Kinetic Energy and Viscous Dissipation to Airway Resistance in Pulmonary Inspiratory and Expiratory Airflows in Successive Symmetric Airway Models With Various Bifurcation Angles.

Publications

Contributions of Kinetic Energy and Viscous Dissipation to Airway Resistance in Pulmonary Inspiratory and Expiratory Airflows in Successive Symmetric Airway Models With Various Bifurcation Angles.

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