Lung function measured by impulse oscillometry and spirometry following eucapnic voluntary hyperventilation: DISCUSSION (4)

Currently, there is no consensus on IOS criteria for the diagnosis and grading of airway obstruction. In the present study, we provided cutoff criteria, sensitivity and predictive values for 80% specificity to the gold standard of 10% change in FEV1 after EVH. We identified significant correlations of peak falls in FEV1 to post-EVH increases in R5, Fres, X and AX. Our study supports R5 per cent change and change in AX (cm H2O/L) as the most sensitive indices of airway obstruction; a 50% increase in R5 and a postchallenge AX value of greater than 12 cm H2O/L provided 90% sensitivity to peak fall in FEV1. This is in agreement with Goldman et al, who demonstrated that inspiratory R5 and AX are most sensitive to daily changes in respiratory status. buy asthma inhaler
In summary, substantial and significant changes in ^ Fe, X and AX were noted after EVH, and all were significantly correlated with post-EVH falls in FEV1. We defined acceptable cutoff criteria for determining postchallenge airway obstruction for per cent change in R5 and increases in AX. The sensitivities of these measures to post-EVH falls in FEV1 support the use of IOS as an acceptable method for diagnosis of airway obstruction and AHR; these measures can be used with patients where accurate and reliable spirometry measures may be difficult to obtain.

Category: Lung function

Tags: Airway hyperresponsiveness, Dry air, Eucapnic voluntary hyperpnea, Exercise-induced bronchoconstriction, Forced oscillation