Experimental Analysis of Air Flows in Bronchial Airway Models in the Cases of Natural Breathing and HFOV

Abstract

The mechanism of gas transfer, flow pattern and diffusion in respiratory air flow at the end zone of human lung, especially in bronchial and alveoli, has not been clarified in detail. Recently, it is known that high frequency oscillatory ventilation (HFOV) is an effective treatment for respiratory distress syndrome. However, the frequency effect on ventilation in relation to the gas transfer efficiency at the end zone of lungs has not been investigated. The velocity profile of oscillatory air flow in bronchial tube is one of the fundamental factors to consider the frequency effect. In this paper, velocity profiles of oscillatory flows in micro scale models of bronchial airway with single- and multi-bifurcation have been investigated for different frequencies corresponding to resting breathing and HFOV by using micro Particle Image Velocimetry (micro PIV). The temporal changes of velocity profiles were reconstructed by phase-averaged velocity maps obtained by micro PIV measurements, and the effect of frequency on the velocity profile in bronchial models has been discussed.