[Pneumodynamics: Respiratory Physiology Related to Anesthesiology]

Although pneumodynamics is the most basic research field in the respiratory management, the number of the researchers is rapidly decreasing in this century. This is not because of the maturing of pneumodynamics but because the conventional theory has been wrong. The authors have been investigating this area theoretically and experimentally for more than ten years and propsed novel pneumodynamics based on dynamic imaging technique during breathing and computational fluid dynamics. In this paper, we first indicate the dynamic collapse of the intra-mediastinal airway during maximum forced expiration in emphysematous patients visualized by 4D-CT images, and explain its mechanism in terms of fluid dynamics where the turbulence of airflow in the large airway plays an important role. Although conventional pneumodynamics is based on electric circuit analogy, it has a crucial defect that the turbulence of airflow is never contained. Then, we will introduce a 4D alveolar model which explains how the alveolar shape changes during breathing based on experimental images, and indicate that the essential morphological change in diffuse alveolar damage (DAD) is the alveolar collapse, which has been misrecognized as "thickening of the alveolar wall". The new era of respiratory physiology has just begun in Japan.