Vor- und Nachteile der Körperplethysmographie als klinische Lungenfunktionsprüfung

Abstract

Lung function studies were performed on 17 healthy subjects and 10 patients with severe emphysema using, alternatively, 2 different methods and equipments. One method, included the measurement of vital capacity, expiratory reserve volume and forced expiratory volume of the 1st sec with a spirometer (Pulmotest-Godart) and of residual volume with the closed circuit helium technique. The 2nd method was based on the measurement of ventilated gas volumes by electrical integration of the signals of a pneumotachograph; functional residual capacity was determined with a volume displacement body plethysmograph using Mead''s technique. The frequency response of all the instruments used was studied. Comparison of the 2 methods was undertaken to determine the possible advantages of plethysmography and of electronic devices in clinical routine. The results agreed for all measurements but those of residual volume in patients with emphysema. In accordance with previous studies, the residual volume measured with the body plethysmograph was considerably larger than the value obtained with the helium method, the difference being due to gas trapped in poorly ventilated alveoli.