Lung function measured by impulse oscillometry and spirometry following eucapnic voluntary hyperventilation (1)Although exercise-induced bronchoconstriction (EIB) has received much attention over the past decade, its mechanisms remain elusive. The response to EIB is most likely multimediated and dependent on the precise stimulus. For example, the pathophysiology of cold air-induced bron-choconstriction involves different mediators than high particulate matter exposure or allergen-mediated bronchoconstriction. Likewise, there are differences of opinion concerning the most appropriate provoking challenge for diagnosis and what cutoff criteria should be employed for specific populations. Some studies have proposed a sports-specific challenge, while others have suggested eucapnic voluntary hyperventilation (EVH) or osmotic challenges. Pharmacological challenges have been found to be less sensitive for identifying EIB in athletes. The measurement most often used to determine airway hyperresponsiveness in athletes, regardless of the specific challenge, is a postchallenge 10% or greater fall in the forced expiratory volume in 1 s (FEV1), which is determined using spirometry from 5 min to 20 min after provocation. buy antibiotics online
Impulse oscillometry (IOS) has been used to measure short-term changes in bronchial tone in bronchodilator tests, and has been shown to correlate with FEV1 and airway resistance, which is determined by body plethysmography. IOS applies brief, random pressure pulses of 5 Hz to 35 Hz generated by a small loudspeaker mounted in series or parallel to a pneumotachometer. The pressure impulses are superimposed to tidal breaths, and real-time recordings are used to estimate total respiratory impedance.