Abstract
Introduction: The internal airflow redistribution under non-invasive ventilation (NIV) is dependent on lobar airway resistance (Raw) and tissue stiffness (S). This study aims to calculate lobar R and S using functional imaging (FI) updated with computational fluid dynamics (CFD).
Methods: 20 persistent hypercapnic COPD GOLD III patients, eligible for NIV treatment, undergo a low dose CT scan at FRC and TLC. From these scans airway tree and lobar expansion (=internal flow distribution) are obtained. Also a simultaneous respiratory flow and esophageal pressure (peso) measurement is performed. CFD calculations using the 3D model, measured flow rates and internal distribution, provide lobar Raw and pressure. The difference in lobar pressure and peso, together with lobar inflow, provide lobar S.
Results: Results show that the lobar Raw profile has a similar shape as the flow profile. The lobar S profile is constant during expiration. During inspiration lobar S does increase exponentially near the end of the inspiration. Furthermore it can be seen that both Raw and S do vary significantly between the different lobes.
Conclusions: Lobar Raw and S can be obtained through FI updated with CFD, by taking a CT scan and a simultaneous flow and peso measurement. Information on these lobar properties can be used to predict the outcome non-invasive ventilation.
- © 2011 ERS
