Lung function measured by impulse oscillometry and spirometry following eucapnic voluntary hyperventilation: DISCUSSION (1)
EVH is a widely accepted provocation challenge for EIB among high-level athletes. In fact, EVH is the challenge recommended by the International Olympic Committee Medical Commission Independent Panel to evaluate EIB in Olympic athletes. In the present study, we compared postchallenge FEV1 measurements obtained from maximal expiratory flow volume manoeuvres with measurements of airway impedance obtained from IOS during tidal breathing in AHR+ and AHR- subjects. Our results demonstrated that IOS provides a reliable method of evaluating airway obstruction as defined from spirometry measurements in a college-aged athletic population. We identified useful criteria for measuring AHR using IOS. buy flovent inhaler
Nine of the 10 subjects with a 10% or greater fall in FEV1 demonstrated a greater than 50% increase from baseline in R5 (or had a postchallenge value of 5.5 cm H2O/lps). Moreover, an additional three subjects who were borderline AHR- by FEV1 demonstrated elevated R5 values consistent with airway obstruction, suggesting that the forced expiratory manoeuvre may mask changes in airway tone. We used postchallenge falls from baseline in FEV1 as the ‘gold standard’ indirect measure of changes in airway calibre after EVH because it is the most widely used index of AHR. FEF25 75 was also used as an indication of airway obstruction; however, postchallenge FEF25-75 is only valid when vital capacity is unaltered. In the present study, vital capacity remained relatively unchanged; therefore, comparisons of FEF25-75 with IOS indices were made. Peak falls in FEF25-75 were highly correlated to peak falls in FEV1.