CFD analysis of the human airways under impedance-based boundary conditions: application to healthy, diseased and stented trachea

Abstract

A computational fluid dynamics model of a healthy, a stenotic and a post-operatory stented human trachea was developed to study the respiration under physiological boundary conditions. For this, outflow pressure waveforms were computed from patient-specific spirometries by means of a method that allows to compute the peripheral impedance of the truncated bronchial generation, modelling the lungs as fractal networks. Intratracheal flow pattern was analysed under different scenarios. First, results obtained using different outflow conditions were compared for the healthy trachea in order to assess the importance of using impedance-based conditions. The resulted intratracheal pressures were affected by the different boundary conditions, while the resulted velocity field was unaffected. Impedance conditions were finally applied to the diseased and the stented trachea. The proposed impedance method represents an attractive tool to compute physiological pressure conditions that are not possible to extract in vivo. This method can be applied to healthy, pre- and post-operatory tracheas showing the possibility of predicting, through numerical simulation, the flow and the pressure field before and after surgery.

Airflow and Particle Deposition Simulations in Health and Emphysema: From In Vivo to In Silico Animal Experiments

“…Constant pressure 17,26,46 or flow rate 11,32 boundary conditions are typically implemented at the distal airway outlets. However, as the flow patterns change in time, CFD simulations should model the breathing unsteadiness, to determine airflow 30 and particle 13 deposition patterns in the lung. Thus, appropriate boundary conditions must be devised.…”

A biomechanical model of pendelluft induced lung injury

“…Most importantly, the high rate of repetition of the amplified shear stress during mechanical ventilation could amplify the effects of abnormally high stresses. A 70% increase in the wall shear stress was also observed by Malvè et al (2012) due to the stenosis in the trachea. Similarly, in the present study, the wall shear stress was found to be significantly amplified surrounding the carina ridges in the distal airways as a consequence of pendelluft flow.…”

Simulation of swallowing dysfunction and mechanical ventilation after a Montgomery T-tube insertion

“…Muscle tissues remain in fact in tension during every cycle performed by the respirator (Malvè et al 2011a). In the literature (Miller et al 2007; Malvè et al 2013), mechanical ventilation has been related to decrease in dynamic elastance of tracheal segment and thinning of the tracheal muscle.…”