Calculated ventilation and effort distribution as a measure of respiratory disease and Heliox effectiveness

Abstract

In spite of numerous clinical studies, there is no consensus on the benefit Heliox mixtures can bring to asthmatic patients in terms of work of breathing and ventilation distribution. In this article we use a 3D finite element mathematical model of the lung to study the impact of asthma on effort and ventilation distribution along with the effect of Heliox compared to air. Lung surface displacement fields extracted from computed tomography medical images are used to prescribe realistic boundary conditions to the model. Asthma is simulated by imposing bronchoconstrictions to some airways of the tracheo-bronchial tree based on statistical laws deduced from the literature. This study illuminates potential mechanisms for patient responsiveness to Heliox when affected by obstructive pulmonary diseases. Responsiveness appears to be function of the pathology severity, as well as its distal position in the tracheo-bronchial tree and geometrical position within the lung.

Predicted airway obstruction distribution based on dynamical lung ventilation data: A coupled modeling‐machine learning methodology

“…More reasonably, we can deduce from the analysis insights on which lung regions and tree generations are affected by plugs. This is useful information when predicting particle deposition [6] or response to Heliox treatments [5]. In Figure 14, we plot the true positive detection rate as a function of the false positive detection rate in two cases: assuming a false positive is actually properly classified if its mother or daughters airways are plugged, and the strict case from Figure 13.…”

“…The greater the resistance on the path, going from the trachea down to exit denoted + , the greater the pressure drop along this path, and the greater the apparent pressure. In case of airway closure, the fed related region expands or contracts at the price of an increased energy cost [5].…”

“…As in [5], based on a literature review, we propose to simulate asthma remodeling by including these two types of constrictions with stochastic laws. To simulate a broncho-constriction, the airway radius is homogeneously divided by a factor so-called constriction ratio.…”

“…This identification step is done following a threestep approach. Image analysis on 4 data gives access to the parenchyma displacement field (see subsection 2.4.1) from which can be computed given a parenchyma partition (5). Knowing the displacement field along the breathing cycle, and assuming that both the parenchyma mechanical properties and the tree topology are known, one can use the ventilation model described in the previous subsection to define a function .Pvv * satisfying a minimization problem.…”

“…However, in clinical practice the airway obstruction distribution is largely unknown. As the response to Heliox treatment may depend on airway closure severity and position within the lung (generational and regional position) [5]; knowing the airway obstruction distribution could give predictive insights on the treatment efficiency. Another clinical application of the airway obstruction distribution could be to predict aerosol deposition, which can be greatly affected by bronchoconstrictions [6].…”