Fundamental Medical and Engineering Investigations on Protective Artificial Respiration (eBook)

Preface 6
Contents 8
Advanced Multi-scale Modelling of the Respiratory System 10
Introduction 10
Computational Model of Pulmonary Alveoli 11
Modelling of Alveolar Tissue 12
Modelling of Alveolar Liquid Lining 13
Geometric Representation 16
Computational Model of Lung Parenchyma 18
Homogenised Parenchyma Model 18
Multi-scale Parenchyma Model 20
Computational Model of the Tracheo-Bronchial Region 24
Coupling of Computational Models for Parenchyma and Conducting Airways 31
Summary and Outlook 35
References 37
Analysis of the Flow in Dynamically Changing Central Airways 42
Introduction 42
Workflow 43
Radiology 44
Animals 44
Ventilation 44
CT Scan Protocol 44
Segmentation Methods 45
Adaptive Region Growing 45
Boosting 46
Cropping 46
Manual Correction 47
Dynamic Segmentation 47
Simulation Methodology 47
Immersed Boundary Approach 48
Method Validation 50
Simulation Setup 50
Results 51
Static Geometry 52
Dynamic Geometry 53
Conclusions and Outlook 55
References 56
Cell Physiology and Fluid Mechanics in the Pulmonary Alveolus and Its Capillaries 58
Introduction 58
Intravital Microscopy of the Murine Lung 59
Pulmonary Capillary Perfusion 59
Microvascular Perfusion in the Ventilated Mouse Lung 59
Modeling the Pulmonary Microcirculation 61
Alveolar Mechanics 63
Measurements of Alveolar Mechanics in Healthy and Acid-Injured Lungs 63
Modeling Alveolar Interaction 66
The Role of the Transient Receptor Potential Channel TRPV4 in Ventilator Induced Lung Injury 70
References 72
Experimental and Numerical Investigation on the Flow-Induced Stresses on the Alveolar-Epithelial-Surfactant-Air Interface 75
Introduction 75
Methods and Material 76
Alveolar Imaging by Optical Coherence Tomography 76
Numerical Modeling of the Epithelial-Surfactant-Air Interface 78
Results 80
Alveolar Imaging by Optical Coherence Tomography 80
SPH Simulations of Fluid-Air Interfaces with Surfactant 83
Conclusion 86
References 86
Fluid Mechanical Equilibrium Processes in a Multi-bifurcation Model 89
Introduction 89
Description 91
Model Geometry and Manufacturing Process 91
Nonlinear Compliance of Terminal Units 92
Experimental Setup 93
Mathematical Formulation 94
Results and Discussion 95
Global and Local Behavior 96
Degree of Influence 97
Frequency Analysis 99
Numerical High-Frequency Analysis 100
Conclusion 102
References 103
In Vivo Microscopy and Analysis of Regional Ventilation in a Porcine Model of Acute Lung Injury 104
Background 104
Materials and Methods 105
Results 106
Conclusion 111
References 112
Magnetic Resonance Imaging and Computational Fluid Dynamics of High Frequency Oscillatory Ventilation (HFOV) 114
Background and Aim of the Project 114
Implementation of MRI during HFOV 115
Computational Fluid Dynamics 118
Geometry Reconstruction with the DLR Toolkit “PiG” 118
Numerical Mesh Generation 119
The “DLR THETA” Code 120
Airway and Lung Models 122
MRIofHFOV 125
Dynamic Analysis of Inert Gas Elimination 126
Intrapulmonary Inert Gas Redistribution - 3He-MRI 126
Imaging and Simulation of Velocity Profiles in Larger Airways 127
Numerical Flow Simulations 130
Continuous Flow Investigations 130
Oscillatory Flow Investigations 132
Conclusion and Outlook 133
References 134
Mechanostimulation and Mechanics Analysis of Lung Cells, Lung Tissue and the Entire Lung Organ 136
Introduction 137
Lung Cells 137
Experimental Mechanostimulation 138
Analysis of Mechanics - Pressure-Volume Relationship as a Substitute for Stress-Strain Relationship 140
Lung Tissue 143
Experimental Mechanostimulation 143
Mechanics Analysis 143
Complete Lung 146
Isolated Lung 147
Animal Model (rat) 148
Analysis of Global Respiratory System Mechanics 151
Mechanics Analysis in Microscopic Scale Complementary to Macroscopic Mechanics Data 152
Alveolar Imaging 153
Alveolar Morphology 154
Local Tissue Mechanics 156
First Assessment of Value 156
References 158
The Effect of Unsteadiness on Particle Deposition in Human Upper and Lung Airways 162
Introduction 162
Numerical Method 163
Results and Discussion 165
Conclusion 171
References 172
Transport at Air-Liquid Bridges under High-Frequency Ventilation 174
Introduction 174
Experimental Model 176
Results 177
Streaming Motion Near Stable Interface 177
Instability at the Interface 181
Coupling of Both Effects 185
Discussion 185
References 187
Author Index 189