Eucapnic voluntary hyperventilation as a bronchoprovocation technique - A development of a standardized dosing schedule in asthmatics

A variety of dosing schedules have been reported for the hyperventilation method of bronchoprovocation testing. To evaluate the effect of challenge technique on the bronchoconstrictive response, we had 16 subjects perform eucapnic voluntary hyperventilation (EVH) with dry, room temperature gas using four different dosing schedules. The hyperventilation challenge dosages included the following: (1) a target minute ventilation (V over dot E) of 20 x FEV(1) for 6 min; (2) a target V over dot E of 15 x FEV(1) for 12 min; (3) an interrupted challenge with a target V over dot E of 30 x FEV(1) for 2 min repeated 3 times; and (4) a target V over dot E of 30 x FEV(1) for 6 min. Challenges 2, 3, and 4 gave identical absolute ventilatory challenges (identical factor FEV(1) x minutes) but at different V over dot E dosages or time, Challenges 1 and 4 were of identical length, but different target V over dot E. The mean postchallenge fall in FEV(1) was 16.6+/-10.9%, 11.0+/-8.1%, 19.6+/-9.9%, and 26.7+/-11.3% for challenges 1, 2, 3, and 4, respectively. The response to an identical EVH challenge (FEV(1) x 30 for 6 min) was reproducible when performed on separate days. We conclude that the challenge technique used for hyperventilation testing will have a significant impact on the bronchoconstrictive response and must be taken into account when interpreting study results. Tests may be quantitatively comparable over a narrow range of challenge time and V over dot E. We recommend that a 6-min uninterrupted EVH challenge using room temperature gas at a target V over dot E of 30xFEV(1) be adopted as the ''standard'' challenge.