Clinical applications of forced oscillation to assess peripheral airway function.
Forced oscillation applies external pressures to the respiratory system to measure respiratory impedance. Impedance of larger central airways may be dissected from that of peripheral airways using multiple oscillation frequencies. Respiratory impedance is calculated by computer-assisted methods that yield separate resistive and reactive components. The reactive component includes respiratory system capacitative and inertive properties, which may be separately visualized for clinical purposes using resonance as a rough dividing line. Low oscillation frequencies comprise those below resonance, and relate most prominently to capacitative properties of peripheral airways. High oscillation frequencies comprise those greater than resonance, which relate most prominently to inertial properties of larger central airways. Measurements of resistance and reactance in patients with peripheral airway disease, before and after therapeutic intervention, manifest characteristic patterns of response in low frequency resistance and reactance measures that appear to be closely correlated with each other. In contrast, changes in large central airways manifest resistance change uniformly over low and high frequencies.
University of California, Los Angeles Department of Medicine, Center for Health Sciences, Los Angeles, CA 90095, USA. mdg@ucla.edu
Michael D
MD
Goldman
Constantine
C
Saadeh
David
D
Ross
D000403:Airway Resistance / Q000502:physiology*; D000818:Animals; D006801:Humans; D008171:Lung Diseases / Q000503:physiopathology*; D009991:Oscillometry / Q000379:methods; D010993:Plethysmography, Whole Body / Q000379:methods; D012129:Respiratory Function Tests / Q000379:methods*; D012137:Respiratory System; D013997:Time Factors