[Lung function diagnosis using multi-frequency oscillometry with reference to lung volume]

The ranking of various oscillometry parameters was to be tested in patients with a broad spectrum of disturbances of pulmonary function, objectified by body plethysmographic and technical oesophageal pressure measurement of the respiratory resistance, lung volumes and lung elasticity. For this purpose the oscillatory resistance Rfo and the phase angle phi were measured at 8, 12 and 16Hz and phi was measured as it changed, depending on the lung volume V. It was found that enhanced respiratory resistance values are satisfactorily represented by Rfo for the purposes of preliminary and basic diagnostics. Besides, enhanced Rfo values are markedly dependent on the frequency, phi being shifted to negative values. Difference between Rfo values at 8 and 16 Hz (delta R8-16) less than 0.7 hPa/l/s phi greater than or equal to -10 degrees can be considered as being still normal with the employed measuring principle and are a valuable supplement for assessing the degree of obstruction. The difference between phi in the medium respiratory position and at 90 or 100% total capacity (delta phi) is less than 5 degrees during slow inspiration in 80% of the patients suffering from emphysema. In 80% of the persons with healthy lungs and those suffering from fibrosis there is an inspiratory negativation of phi (delta phi greater than 5 degrees) so that the phi-V relationship appear suitable for distinguishing patients with restricted vital capacity in respect of emphysema and fibrosis. Patients suffering fron fibrosis differ from healthy subjects by slightly more negative phi values. The borderline values for delta R8-16, phi and delta phi were confirmed in two further series of examinations on children and adolescents.