The Mechanics of Lung Tissue under High-Frequency Ventilation

High frequency ventilation is a radical departure from conventional lung ventilation, with frequencies greater than 2 Hz, and volumes per breath much smaller than the anatomical deadspace. Its use has been shown to benefit premature infants and patients with severe respiratory distress, but a vital question concerns ventilator induced damage to the lung tissue, and a clear protocol for the most effective treatment has not been identified. Mathematical modelling can help in understanding the underlying processes in lung ventilation, and hence in establishing such a protocol. In this paper we describe the use of homogenisation theory to predict the macroscopic behaviour of lung tissue based upon the microstructure of respiratory regions. This approach yields equations for macroscopic air-flow, pressure, and tissue deformation, with parameters which can be determined from a specification of the tissue microstructure and its material properties.