Structured Tree Impedance Outflow Boundary Conditions for 3D Lung Simulations

In this paper, we develop structured tree outflow boundary conditions for modeling the airflow in patient specific human lungs. The utilized structured tree is used to represent the nonimageable vessels beyond the 3D domain. The coupling of the two different scales (1D and 3D) employs a Dirichlet–Neumann approach. The simulations are performed under a variety of conditions such as light breathing and constant flow ventilation (which is characterized by very rapid acceleration and deceleration). All results show that the peripheral vessels significantly impact the pressure, however, the flow is relatively unaffected, reinforcing the fact that the majority of the lung impedance is due to the lower generations rather than the peripheral vessels. Furthermore, simulations of a hypothetical diseased lung (restricted flow in the superior left lobe) under mechanical ventilation show that the mean pressure at the outlets of the 3D domain is about 28% higher. This hypothetical model illustrates potential causes of volutrauma in the human lung and furthermore demonstrates how different clinical scenarios can be studied without the need to assume the unknown flow distribution into the downstream region.

[1]  H Kitaoka,et al.  A three-dimensional model of the human airway tree. , 1999, Journal of applied physiology.

[2]  Timon Rabczuk,et al.  Fluid–structure interaction in lower airways of CT‐based lung geometries , 2008 .

[3]  A. P. Kolesnichenko,et al.  Acute lung injury , 2020, Intensive Care Medicine.

[4]  Timothy J. Pedley,et al.  Pulmonary Fluid Dynamics , 1977 .

[5]  Eric A Hoffman,et al.  Characteristics of airflow in a CT-based ovine lung: a numerical study. , 2007, Journal of applied physiology.

[6]  P. J. Hunter,et al.  Generation of an Anatomically Based Three-Dimensional Model of the Conducting Airways , 2000, Annals of Biomedical Engineering.

[7]  Mette S Olufsen,et al.  Structured tree outflow condition for blood flow in larger systemic arteries. , 1999, American journal of physiology. Heart and circulatory physiology.

[8]  Marek Ancukiewicz,et al.  Higher versus lower positive end-expiratory pressures in patients with the acute respiratory distress syndrome. , 2009, The New England journal of medicine.

[9]  Diane P. Martin,et al.  Incidence and outcomes of acute lung injury. , 2005, The New England journal of medicine.

[10]  B Suki,et al.  Wave propagation, input impedance, and wall mechanics of the calf trachea from 16 to 1,600 Hz. , 1993, Journal of applied physiology.

[11]  M. Olufsen,et al.  Numerical Simulation and Experimental Validation of Blood Flow in Arteries with Structured-Tree Outflow Conditions , 2000, Annals of Biomedical Engineering.

[12]  G. Michaud,et al.  Mechanisms of ventilator-induced lung injury: the clinician's perspective , 2003, Critical care.

[13]  M. Zamir,et al.  The Physics of Pulsatile Flow , 2000, Biological Physics Series.

[14]  E. Hoffman,et al.  Characteristics of the turbulent laryngeal jet and its effect on airflow in the human intra-thoracic airways , 2007, Respiratory Physiology & Neurobiology.

[15]  L Puybasset,et al.  A lung computed tomographic assessment of positive end-expiratory pressure-induced lung overdistension. , 1998, American journal of respiratory and critical care medicine.

[16]  Charles A. Taylor,et al.  Outflow boundary conditions for three-dimensional finite element modeling of blood flow and pressure in arteries , 2006 .

[17]  D. Evans,et al.  Small airways: a time to revisit? , 1998, Thorax.

[18]  Y Liu,et al.  Modeling the bifurcating flow in a human lung airway. , 2002, Journal of biomechanics.

[19]  B Suki,et al.  Airway inhomogeneities contribute to apparent lung tissue mechanics during constriction. , 1996, Journal of applied physiology.

[20]  P. Macklem,et al.  The physiology of small airways. , 1998, American journal of respiratory and critical care medicine.

[21]  E. Weibel.  Morphometry of the Human Lung , 1965, Springer Berlin Heidelberg.

[22]  Charles A. Taylor,et al.  Fractal network model for simulating abdominal and lower extremity blood flow during resting and exercise conditions , 2007, Computer methods in biomechanics and biomedical engineering.

[23]  Wolfgang A. Wall,et al.  Coupling strategies for biomedical fluid–structure interaction problems , 2010 .

[24]  C. Carvalho,et al.  Effect of a protective-ventilation strategy on mortality in the acute respiratory distress syndrome. , 1998, The New England journal of medicine.

[25]  T Gemci,et al.  Computational model of airflow in upper 17 generations of human respiratory tract. , 2008, Journal of biomechanics.

[26]  Kenneth R. Lutchen,et al.  An Anatomically Based Hybrid Computational Model of the Human Lung and its Application to Low Frequency Oscillatory Mechanics , 2006, Annals of Biomedical Engineering.

[27]  J. Guttmann,et al.  Alveolar recruitment in acute lung injury. , 2006, British journal of anaesthesia.

[28]  Wolfgang A. Wall,et al.  A nested dynamic multi-scale approach for 3D problems accounting for micro-scale multi-physics , 2010 .

[29]  Claudio Cobelli,et al.  A Morphometric Model of Lung Mechanics for Time-Domain Analysis of Alveolar Pressures during Mechanical Ventilation , 2002, Annals of Biomedical Engineering.

[30]  Arthur S Slutsky,et al.  Effect of mechanical ventilation on inflammatory mediators in patients with acute respiratory distress syndrome: a randomized controlled trial. , 1999, JAMA.

[31]  Wolfgang A. Wall,et al.  Towards a comprehensive computational model for the respiratory system , 2010 .

[32]  C. Kleinstreuer,et al.  Airflow structures and nano-particle deposition in a human upper airway model , 2004 .

[33]  C Kleinstreuer,et al.  An adjustable triple-bifurcation unit model for air-particle flow simulations in human tracheobronchial airways. , 2009, Journal of biomechanical engineering.

[34]  D E Olson,et al.  Models of the human bronchial tree. , 1971, Journal of applied physiology.

[35]  Wolfgang A. Wall,et al.  Modeling the Mechanical Behavior of Lung Tissue at the Microlevel , 2009 .

[36]  K. Hickling,et al.  Low mortality associated with low volume pressure limited ventilation with permissive hypercapnia in severe adult respiratory distress syndrome , 2005, Intensive Care Medicine.

[37]  R. Baba,et al.  Protective ventilation of patients with acute respiratory distress syndrome. , 2004, British journal of anaesthesia.

[38]  A. Green,et al.  Modelling of peak-flow wall shear stress in major airways of the lung. , 2004, Journal of biomechanics.

[39]  H. Fessler,et al.  Mechanical ventilation in acute lung injury and acute respiratory distress syndrome. , 2000, Clinics in chest medicine.

[40]  R. Djukanović,et al.  The role of small airways in lung disease. , 2002, Respiratory medicine.

[41]  Geoffrey McLennan,et al.  CT-based geometry analysis and finite element models of the human and ovine bronchial tree. , 2004, Journal of applied physiology.

[42]  Kenneth R. Lutchen,et al.  How Heterogeneous Bronchoconstriction Affects Ventilation Distribution in Human Lungs: A Morphometric Model , 2004, Annals of Biomedical Engineering.