[Inspiratory phase angle behavior in oscilloresistometry]

Oscillatory measurement of resistance can get more practical relevance including the phase angle (PSI) and the volume dependence. Different findings during deep inspiration in patients with pulmonary emphysema (PSI unchanged) and with pulmonary fibrosis (PSI-Negativation) are known. To explain these findings transpulmonary pressure (Ptp) was measured parallel to PSI in 85 subjects. PSI-negativation was found in 31 of 43 patients with pulmonary fibrosis and in 10 of 19 healthy subjects. Patients with pulmonary emphysema have nearly constant or slight positive phase angles. Subjects with negativation of phase angle have significantly higher Ptp-levels at 100% TLC. This high pressure is reached by an in comparison to volume overproportional increase of pressure in the end part of the lung expansion curve. It is proposed to estimate the PSI-V-dependence in ranges from middle level of breathing to 75% of vital capacity VC and from 75% to 100% VC separately. By this modification the qualitative noninvasive assessment of lung compliance could be more efficient. Several findings indicate, that the observed secondary periodic of PSI are dependent from heart rhythm and therefore from intrathoracic blood volume.