The role of impulse oscillometry in detecting airway dysfunction in athletes.

BACKGROUND Impulse oscillometry (IOS) has previously been proposed to provide greater sensitivity than spirometry when employed with indirect bronchoprovocation testing for the diagnosis of airway dysfunction in athletes. However, this recommendation is based on a highly selected population of symptomatic patients. OBJECTIVE To compare IOS, spirometry and respiratory symptoms following indirect bronchoprovocation in a screened cohort of athletes. METHODS One hundred and one recreational athletes were recruited. Respiratory symptoms were assessed via the Dyspnoea-12 questionnaire. Spirometry and IOS were performed pre and post a eucapnic voluntary hyperpnoea (EVH) challenge. RESULTS Ninety-four athletes completed the study. Sixteen athletes (17%) were positive for airway dysfunction based on spirometry (i.e. ≥ 10% fall in FEV1) and 17 athletes (18%) based on IOS (i.e. ≥ 50% increase in R5). Only nine athletes (10%) met both diagnostic thresholds. A poor relationship was observed between respiratory symptoms (i.e. Dyspnoea-12 score) and all spirometry and IOS variables. A direct relationship was observed between percentage change in R5 (r = 0.65), Z5 (r = 0.68), RF (r = 0.65), AX (r = 0.69) and the maximum fall in FEV1 (ΔFEV1max; p < 0.001). A weak relationship was observed between R20 (r = 0.27), X5 (r = 0.37) and ΔFEV1max (p < 0.01). CONCLUSION Impulse oscillometry and spirometry do not concur precisely following indirect bronchoprovocation. However, IOS detects additional cases of airway dysfunction in athletes and therefore may provide diagnostic value in this population. Further work is required to establish diagnostic thresholds and fully determine the place of IOS in screening athletes for airway dysfunction.