The site of airway obstruction among patients of emphysema: role of impulse oscillometry.
OBJECTIVE
To detect the site of airway obstruction in patients of emphysema by impulse oscillometry (IOS) and to compare its observatios with flow volume loop (FV loop) studies.


METHODS
Twenty-five patients of emphysema were subjected to both impulse oscillometry (IOS) and conventional spirometry. The resulting impedance spectra by IOS and FV loop were utilized to identify the site of airway obstruction in each of the patients. Both methods applied were also compared for sensitivity to identify airway and specify the site of obstruction.


RESULTS
Four patients were excluded from the final analysis as their impedance spectra showed significant upper airway influence, which would have made the localization of the site of airway obstruction by IOS invalid. Both IOS and FV loop could detect airway obstruction in all 21 patients. FV loop localized the site of obstruction as combined central and peripheral airways in 15 patients (71.4%) and as peripheral in 6 (28.6%).The IOS however, revealed the presence of the predominant site of obstruction peripheral in all the 21 patients, and both central and peripheral obstruction in 5 patients (23.8%).


CONCLUSIONS
IOS had proven to be advantageous over FV loop studies as it could identify central and peripheral airway obstruction separately and established the predominant site of obstruction.
Hira
Hs
H
MD, DM, Professor of Medicine Chief, Pulmonary Medicine and Sleep Center, Maulana Azad Medical College and Lok Nayak Hospital, New Delhi - 110 002, India.
Munjal
Jitender
J
Zachariah
Sanjay
S
Chauhan
Mr
M
Singh
Anshu
A
J Appl Physiol. 1973 Feb;34(2):143-53
4686346
Am Rev Respir Dis. 1991 Nov;144(5):1202-18
1952453
J Appl Physiol. 1967 Mar;22(3):395-401
4960137
Eur Respir J. 1999 Apr;13(4):761-6
10362037
Am J Med. 1974 Aug;57(2):171-82
4843891
N Engl J Med. 1968 Jun 20;278(25):1355-60
5650164
N Engl J Med. 1973 Feb 22;288(8):395-8
4684043
Am J Med. 1972 Jun;52(6):725-37
5030170
Chest. 1982 May;81(5):586-91
7075278
Am Rev Respir Dis. 1975 Jun;111(6):755-62
1137244
Am Rev Respir Dis. 1985 Sep;132(3):712-4
4037543
Clin Chest Med. 1983 Sep;4(3):337-50
6357598
J Clin Invest. 1975 Nov;56(5):1210-30
1184746
J Appl Physiol Respir Environ Exerc Physiol. 1978 May;44(5):728-37
649475
Chest. 1976 Jan;69(1):51-5
1244288
J Clin Invest. 1973 Sep;52(9):2117-28
4727452