Density dependence of respiratory input impedance in normal subjects.
1. The forced oscillation technique is a non-invasive and effort-independent test used to characterize the mechanical impedance of the respiratory system. Total respiratory impedance was assessed from 4 to 52 Hz in 15 normal subjects breathing air and a helium-oxygen mixture. 2. Breathing helium-oxygen reduced respiratory resistance and its frequency dependence as well as respiratory reactance very significantly. Resonant frequency during He-O2 breathing was 1.88 times higher than during air breathing. 3. It is concluded that by impedance measurement of the respiratory system in normal subjects a density-dependent decrease of respiratory resistance due to decreased turbulence in the larger airways and a density-dependent decrease in the inductive reactance can be found during breathing of low density gas mixtures.
Department of Pulmonary Diseases, State University Limburg, Maastricht, The Netherlands.
E F
EF
Wouters
F J
FJ
Lándsér
A H
AH
Polko
B F
BF
Visser
D000403:Airway Resistance; D005583:Fourier Analysis; D006371:Helium; D006801:Humans; D008297:Male; D008954:Models, Biological; D010101:Oxygen Consumption; D010992:Plethysmography, Impedance / Q000592:standards*; D012016:Reference Values; D012129:Respiratory Function Tests / Q000592:standards*
D006371:Helium