Work

Intratidal Overdistention and Derecruitment in the Injured Lung: A Simulation Study

Year: 2016

Type: article

Abstract: Goal: Ventilated patients with the acute respiratory distress syndrome (ARDS) are predisposed to cyclic parenchymal overdistention and derecruitment, which may worsen existing injury. We hypothesized that intratidal variations in global mechanics, as assessed at the airway opening, would reflect such distributed processes. Methods: We developed a computational lung model for determining local instantaneous pressure distributions and mechanical impedances continuously during a breath. Based on these distributions and previous literature, we simulated the within-breath variability of airway segment dimensions, parenchymal viscoelasticity, and acinar recruitment in an injured canine lung for tidal volumes(VT) of 10, 15, and 20 mL · kg-1and positive end-expiratory pressures (PEEP) of 5, 10, and 15 cm H2O. Acini were allowed to transition between recruited and derecruited states when exposed to stochastically determined critical opening and closing pressures, respectively. Results: For conditions of low VTand low PEEP, we observed small intratidal variations in global resistance and elastance, with a small number of cyclically recruited acini. However, with higher VTand PEEP, larger variations in resistance and elastance were observed, and the majority of acini remained open throughout the breath. Changes in intratidal resistance, elastance, and impedance followed well-defined parabolic trajectories with tracheal pressure, achieving minima near 12 to 16 cm H2O. Conclusion: Intratidal variations in lung mechanics may allow for optimization of ventilator settings in patients with ARDS, by balancing lung recruitment against parenchymal overdistention. Significance: Titration of airway pressures based on variations in intratidal mechanics may mitigate processes associated with injurious ventilation.

Source: IEEE Transactions on Biomedical Engineering

DOI: 10.1109/tbme.2016.2572678

Authors: Reza Amini, Jacob Herrmann, David W. Kaczka

Institutions: Beth Israel Deaconess Medical Center, Harvard University, University of Iowa

Language: English

Topic: Respiratory Support and Mechanisms

Subfield: Pulmonary and Respiratory Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: green

Funders: National Institutes of Health, National Heart, Lung, and Blood Institute