[Expanded oscillo-resistometry--an independent method for studying lung function tests]

The lung is a complicated organ, both physiologically and from the point of view of carrying out measurements. The tissue is elastic, as also is the enclosed air. Since the alveolar pressure cannot be measured directly, various component factors or resistances are measured. While whole-body plethysmography measures almost exclusively the actual flow or airway resistance, the forced oscillation technique measures the acoustic resistance of the entire respiratory tract. Although the two methods correlate to a high degree, considered objectively, they are unable to produce identical results. The forced oscillation technique must be considered a separate measuring method, which belongs in the area for which it was developed - in the office of the privately practising internist or general practitioner. If the forced oscillation technique provides the physician with a technically simple method which does not put any stress on the patient, and which, quickly and largely independently of the cooperation of the patient, is capable of accurately differentiating or quantitatively assessing pulmonary emphysema and endobronchial obstruction - that is, the pulmonary diseases that are by far and away the most common - it will already have fulfilled a very important requirement. Pneumologists attach great diagnostic significance to the Ros-respiratory volume curve and the phase angle. While the physician is already able to interpret the Ros curve in terms of the pathological state of the patient, the significance of the phase angle still needs to be investigated in more detail. In addition, it must be confirmed that the forced oscillation technique reacts sensitively to, for example, the administration of theophylline, and established whether, in patients with allergic diseases, it can reveal early changes that might escape detection by whole-body plethysmography.