Minimization of Ventilator-Induced Lung Injury in ARDS Patients – Part I: Complex Model of Mechanically Ventilated ARDS Lungs

Abstract

A complex model of mechanically ventilated ARDS lungs is proposed in the paper. This analogue is based on a combination of four components that describe breathing mechanics: morphology, mechanical properties of surfactant, tissue and chest wall characteristics. Physical-mathematical formulas attained from experimental data have been translated into their electrical equivalents and implemented in MultiSim software. To examine the adequacy of the forward model to the properties and behaviour of mechanically ventilated lungs in patients with ARDS symptoms, several computer simulations have been performed and reported in the paper. Inhomogeneous characteristics observed in the physical properties of ARDS lungs were mapped in a multi-lobe model and the measured outputs were compared with the data from physiological reports. In this way clinicians and scientists can obtain the knowledge on the moment of airway zone reopening/closure expressed as a function of pressure, volume or even time. In the paper, these trends were assessed for inhomogeneous distributions (proper for ARDS) of surfactant properties and airway geometry in consecutive lung lobes. The proposed model enables monitoring of temporal alveolar dynamics in successive lobes as well as those occurring at a higher level of lung structure organization, i.e. in a point P0 which can be used for collection of respiratory data during indirect management of recruitment/de-recruitment processes in ARDS lungs. The complex model and synthetic data generated for various parametrization scenarios make possible prospective studies on designing an indirect mode of alveolar zone management, i.e. with a minimized risk of repeated alveolar recruitment/de-recruitment and mechanical overstraining of lung tissues.

Ventilator-induced lung injury in ARDS

“…7,16 This strategy was evaluated to be effective in controlling the death rates occurring due to ventilationinduced lung injuries in the patients of ARDS. 3,5,8 Management of capillary and arterial pressure: Making use of vasopressors in addition to the administration of IV fluids can significantly help in achieving high mean arterial pressure and cerebral perfusion pressure. When capillary pressure is high by keeping the arterial pressure high, the chances of acquiring ventilator-induced lung injury are significantly minimized and, therefore, can act as a strategy to prevent ventilator-induced lung injuries.…”

“…Acute respiratory distress syndrome is observed as a comorbidity in multiple illnesses and occurs in 2.5-19% of critically ill patients admitted in ICUs. [1][2][3][4] It has been observed that the patients likely to be the first hit by acute respiratory distress syndrome show different symptoms managed by mechanical ventilation, which is associated with volutrauma and barotrauma. 5,6 In most cases, mechanical ventilation is observed to be a factor that induces lung damage, and it has been identified that implementation of mechanical ventilation can aggravate the adverse effects after the initial trauma experienced by the lungs.…”