Whole-lung finite-element models for mechanical ventilation and respiratory research applications

Abstract

Mechanical ventilation has been a vital treatment for Covid-19 patients with respiratory failure. Lungs assisted with mechanical ventilators present a wide variability in their response that strongly depends on air-tissue interactions, which motivates the creation of simulation tools to enhance the design of ventilatory protocols. In this work, we aim to create anatomical computational models of the lungs that predict clinically-relevant respiratory variables. To this end, we formulate a continuum poromechanical framework that seamlessly accounts for the air-tissue interaction in the lung parenchyma. Based on this formulation, we construct anatomical finite-element models of the human lungs from computed-tomography images. We simulate the 3D response of lungs connected to mechanical ventilation, from which we recover physiological parameters of high clinical relevance. In particular, we provide a framework to estimate respiratory-system compliance and resistance from continuum lung dynamic simulations. We further study our computational framework in the simulation of the supersyringe method to construct pressure-volume curves. In addition, we run these simulations using several state-of-the-art lung tissue models to understand how the choice of constitutive models impacts the whole-organ mechanical response. We show that the proposed lung model predicts physiological variables, such as airway pressure, flow and volume, that capture many distinctive features observed in mechanical ventilation and the supersyringe method. We further conclude that some constitutive lung tissue models may not adequately capture the physiological behavior of lungs, as measured in terms of lung respiratory-system compliance. Our findings constitute a proof of concept that finite-element poromechanical models of the lungs can be predictive of clinically-relevant variables in respiratory medicine.

An enhanced respiratory mechanics model based on double-exponential and fractional calculus

“…Parameter estimation for all the above-mentioned ordinary differential equations with constant coefficients can be performed using the following procedure ( Bates, 2009 ; Redmond et al, 2017 ; Avilés-Rojas and Hurtado, 2022 ). The first observation is that all the models analyzed in this paper may be recasted as where denotes any linear or nonlinear term of the differential equation, for example, may represent , , , etc., while is the corresponding set of coefficients, i.e., the quantities to be estimated.…”

“…Parameter estimation for all the above-mentioned ordinary differential equations with constant coefficients can be performed using the following procedure (Bates, 2009;Redmond et al, 2017;Avilés-Rojas and Hurtado, 2022). The first observation is that all the models analyzed in this paper may be recasted as…”

Quasi‐dynamic breathing model of the lung incorporating viscoelasticity of the lung tissue

“…Computational models have been developed for surface of the lung 9 for identifying appropriate constitutive models using an inverse approach. Continuum poromechanical framework, integrated with lung's outer geometry, has led to implicit and seamless modeling of air‐tissue interaction enabling replicability of clinically relevant respiratory variables 10 . However, accounting for mucus‐air‐tissue interaction and representation of mucus distributions is likely non‐trivial.…”

“…Continuum poromechanical framework, integrated with lung's outer geometry, has led to implicit and seamless modeling of air-tissue interaction enabling replicability of clinically relevant respiratory variables. 10 However, accounting for mucus-air-tissue interaction and representation of mucus distributions is likely non-trivial. Mauroy et al 11 developed a quasi-static numerical model of breathing and mucus flow within the implicit representation of the lung with an idealized deformable symmetric bifurcating tree, 12 based on the principles of steady-state fluid flow and elastic solid mechanics.…”