THE SITE OF AIRWAY OBSTRUCTION AMONG PATIENTS OF EMPHYSEMA: ROLE OF IMPULSE OSCILLOMETRY

OBJECTIVES: 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.