Transient Mechanical Response of Lung Airway Tissue during Mechanical Ventilation.

Israr Ibrahim,Ramana Pidaparti,Parya Aghasafari

doi:10.3390/bioengineering3010004

Abstract

Patients with acute lung injury, airway and other pulmonary diseases often require Mechanical Ventilation (MV). Knowledge of the stress/strain environment in lung airway tissues is very important in order to avoid lung injuries for patients undergoing MV. Airway tissue strains responsible for stressing the lung’s fiber network and rupturing the lung due to compliant airways are very difficult to measure experimentally. Multi-level modeling is adopted to investigate the transient mechanical response of the tissue under MV. First, airflow through a lung airway bifurcation (Generation 4–6) is modeled using Computational Fluid Dynamics (CFD) to obtain air pressure during 2 seconds of MV breathing. Next, the transient air pressure was used in structural analysis to obtain mechanical strain experienced by the airway tissue wall. Structural analysis showed that airway tissue from Generation 5 in one bifurcation can stretch eight times that of airway tissue of the same generation number but with different bifurcation. The results suggest sensitivity of load to geometrical features. Furthermore, the results of strain levels obtained from the tissue analysis are very important because these strains at the cellular-level can create inflammatory responses, thus damaging the airway tissues.

Highlights

Patients with respiratory problems whose lungs are compromised are treated with MechanicalVentilation (MV) to assist them with breathing
The incidence of respiratory failures resulting from ventilator-associated lung injury (VALI) [3,4,5] is increasing due to the fact that there are still unanswered questions with regards to the transmission of mechanical forces into lung tissues resulting from Mechanical Ventilation (MV)
The transient air pressure was used in structural analysis to obtain mechanical strain experienced by the airway tissue wall

Summary

Introduction

Patients with respiratory problems whose lungs are compromised are treated with MechanicalVentilation (MV) to assist them with breathing. The incidence of respiratory failures resulting from ventilator-associated lung injury (VALI) [3,4,5] is increasing due to the fact that there are still unanswered questions with regards to the transmission of mechanical forces into lung tissues resulting from MV. Mechanical aspects of VILI have been reported in past works, such as [3,4,5] From these studies, ventilator management practices have been developed, such as maintaining positive end-expiration pressure. Ventilator management practices have been developed, such as maintaining positive end-expiration pressure Despite this development, MV-induced damage may still lead to systemic organ failure called biotrauma [6]. Mechanical strain caused by ventilators has been shown to cause cell signaling, leading to inflammation [7]. It has been shown that the inflammation depends on the mode of MV [8,9]

Results

Discussion

Conclusion