Affiliations: Graduate School of Science and Engineering, Saitama
University, Sakura-ku, Saitama, 338-8570, Japan. E-mail:
kjinkyu@lamb.mech.saitama-u.ac.jp | Mechanical Science Division, Graduate School of
Science and Engineering, Saitama University, Sakura-ku, Saitama, 338-8570,
Japan
Abstract: As the mechanism of gas transport and exchange in human respiratory
ventilation, the complicated processes of mixing and diffusion in airways of
human lungs are considered. However the mechanism has not been clarified
enough. On the other hand, the analysis of detailed mechanism in the case of
artificial ventilation like HFOV (High Frequency Oscillatory Ventilation) is
strongly required for the development of clinical treatments on patients with
respiration disorder. In HFOV, it is considered that pendelluft becomes one of
the important factors of gas transport and exchange because of high frequency
ventilation in comparison with natural breathing. As increase of the frequency,
the different time constants of lung units generate phase lag of ventilation in
airways of lungs. The phase lag of ventilation causes to generate pendelluft.
The time constant is determined by compliance and flow resistance of lung unit.
In order to investigate the effect of the different time constants induced by
the difference of flow resistance in a part of respiratory bronchiole of human
lungs, the experimental study has been carried out by using multi-bifurcated
micro channels as a model of bronchiole. The flow resistance in the model
channels was produced by a stenosis. The velocity distributions of ventilation
flows in the channels with and without the stenosis have been measured by using
μ-PIV technique. The results obtained show the frequency effects
on the flow pattern in the bronchiole model channels and the appearance of
pendelluft.
