Ventilation Rates Achieved in Eucapnic Voluntary Hyperpnea Challenge and Exercise-Induced Bronchoconstriction...

Exercise-induced bronchoconstriction (EIB) affects approximately 50% of young asthma patients, impairing their participation in sports and physical activities. Eucapnic voluntary hyperpnea (EVH) is an approved surrogate challenge to exercise for objective EIB diagnosis, but the required minimum target hyperventilation rates remain unexplored in this population. This study aimed to evaluate the association between the achieved ventilation rates (VRs) during a challenge and EIB-compatible response (EIB-cr) in young asthma patients.

This cross-sectional study included 72 asthma patients aged 10-20 years. Forced expiratory volume in the first second (FEV1) was measured before and 5, 15, and 30 min after the EVH. The target VR was set at 21 times the individual's baseline FEV1. A decrease of > 10% in FEV1 after the challenge was considered an EIB-cr. The challenge was repeated after 48-72 h in those without an EIB-cr.

Thirty-six individuals had an EIB-cr at initial evaluation. The median VRs achieved was not different between individuals with and without an EIB-cr (19.8 versus 17.9; p = 0.619). The proportion of individuals with an EIB-cr was nor different comparing those who achieved (12/25) or not (24/47) the calculated target VRs (p = 0.804). At the repeated EVH challenge an EIB-cr was observed in 14/36 individuals with a negative response in the first evaluation, with no differences in achieved VRs between the two tests (p = 0.463).

Irrespective of the achieved VR, an EIB-compatible response after an EVH challenge must be considered relevant for clinical and therapeutic judgment and negative tests should be repeated.