IOS for differential diagnosis of asthma and COPD: An Indian experience

International Conference and Exhibition on Lung Disorders & Therapeutics

July 13-15, 2015 Baltimore, Maryland, USA

Arvind Bhome, Bill Brashier, Vandana Vincent, Subhabarata Moitra and Sapna Madas

Posters-Accepted Abstracts: J Pulm Respir Med

Abstract :

Introduction: Managing severe persistent asthma with airway remodeling and severe or very severe COPD is a daily challenge for the respiratory practitioner. Impulse Oscillometry (IOS) is simple technique with potential to measure frequency dependent resistive, elastic and inertial properties of the lung during tidal breathing. Understanding the differences in lung functions measured by IOS between asthma and COPD, compared to healthy subjects should help in differential diagnosis and choice of therapy. Aim: To compare lung physiology by IOS in patients of COPD, Asthma versus Healthy subjects. Methods: 100 stable-asthma, 101 stable-COPD and 55 healthy subjects underwent pre-post bronchodilator IOS measurement according to ERS/ ATS criteria. Age-corrected Post-bronchodilator measurements were used for comparison analysis using log transformation and ANCOVA. Results: Compared with healthy subjects, both asthmatic and COPD-subjects had higher resistance (R5Hz, R20Hz), impedance at 5Hz (Z5Hz), reactance at 5Hz (X5Hz), area-of-reactance (Ax) and resonance-frequency (Rf). The differences between asthma and COPD were not appreciable with pre-bronchodilator IOS parameters. However, compared to asthmatics, COPD subjects had higher post bronchodilator frequency dependency R5Hz-R20Hz [0.15 (0.07,0.30) vs. 0.30 (0.21,0.41) P=0.016], X5Hz [kPa/(L/s)] [(median (IQR): -0.20 (-0.37, -0.13) vs. -0.51 (-0.84, -0.29) p<0.0001)], Ax [kPa/L] [median (IQR): (1.293 (0.673, 3.725 ) vs. 4.702 (2.741, 7.796), p<0.0001)] and Rf [median (IQR) 22.34 (16.40, 28.38) 30.73 (25.60, 35.92 ), p<0.0001]. Conclusion: IOS can differentiate severe asthma and COPD. The differences are appreciable with post-bronchodilator elastance components (higher in COPD patients e.g. frequency dependency, X, Fers and AX values) but not resistive components, at tidal breathing maneuvers.