Usefulness of impulse oscillometry in patients with asymptomatic bronchial asthma

Park, Jeong Youp; Kim, Cheol Woo; Lee, Jae Hoon; Park, Yoon Soo; Park, Byung Gyu; Park, Jung Won; Hong, Chein Soo

Abstract

BACKGROUND: Impulse oscillometry (IOS) is a valuable method for evaluating respiratory func- tion in a patient with bronchial asthma. There have been no reports on compliance assessment of the remodeled airway by estimation of the relationship between resistance and breathing volume in asymptomatic asthma using IOS.
OBJECTIVE
This study was performed to evaluate whether IOS could distinguish asymptomatic asthma from healthy control and detect altered physiology of the airway due to airway remodeling in asymptomatic asthmatic patients with normal pulmonary function. METHOD: 16 healthy and 16 asymptomatic patients with bronchial asthma were asked to breathe with the usual tidal volume (Vt) and with twice the amount of Vt. Using IOS, impedance, resistance for frequency at 5Hz and 20 Hz, reactance, and resonant frequency were measured.
RESULTS
Resonant frequency was significantly higher in asymptomatic asthma than in healthy control for breathing with both usual Vt and twice the amount of Vt (mean+/-S.E.M. 16.35+/-1.44 Hz vs 13.34+/-0.66 Hz, 16.27+/-0.72 Hz vs 13.68+/-0.66 Hz, p<0.05 respectively), but the discriminant power of resonant frequency for distinguishing asymptomatic asthma from healthy control was low. There were no significant differences of other IOS parameters between asthma and control groups. Compared with control group, asymptomatic asthma group showed no significant change of IOS parameters according to breathing volume change.
CONCLUSION
In this study, we could not find any IOS parameters sensitive enough to detect altered physiology of the remodeled airway in patients with asymptomatic bronchial asthma. Further studies are recommended to improve sensitivity of IOS method for investigating airway physiology in bronchial asthma.