[Impedance analysis using the random noise oscillation method and a body box].
The frequency characteristics (at 10-40 Hz) of airway (Za) and tissue (Zt) impedances in patients with chronic bronchitis (CB), chronic pulmonary emphysema (CPE) and interstitial pneumonitis (IP) were examined using the random noise oscillation method and a body box. Compared with normal subjects, Zar (r:real part) was elevated in cases of CB, but not in those with CPE. Zai (i:imaginary part) was decreased in cases of CB and CPE. Applying an electromechanical analogy to these results, it was inferred that CB increases both central and peripheral airway resistance, while CPE only increases peripheral resistance. In CPE, but not in CB, Ztr fell; only Zti decreased in IP, which suggests a decrease in mass per unit of lung tissue in CPE and a loss of pulmonary compliance in IP. We also measured the impedance of a dog with acute pulmonary edema induced by oleic acid. Zar an Ztr were increased but Zti was decreased, which corresponded with the increase of airway resistance due to hypersecretion and the decrease of lung compliance. We conclude that this method is useful in differentiating interstitial disorders from COLD, and also CB from CPE, because it can detect lung stiffness and can identify sites of airway narrowing.
Mishima
M
M
Fukunaga
T
T
Kawakami
K
K
Tanaka
E
E
Tsutsui
T
T
Kuno
K
K
D000328:Adult; D000368:Aged; D000403:Airway Resistance; D000818:Animals; D003937:Diagnosis, Differential; D004285:Dogs; D004568:Electrodiagnosis / Q000379:methods; D005260:Female; D006801:Humans; D008170:Lung Compliance; D008171:Lung Diseases / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D012129:Respiratory Function Tests / Q000379:methods