HYPERVENTILATION CORRECTED TO CHILDS REST ING VENTILATION RATE

In order to validate an Isocapnic Voluntary Hyperventilation (NH) test applicable to daily practice and to adapt the stimulus to height, 9 h ealthy and 15 asthmatic children performed a Resting Ventilation Rare (RVR)-corrected IVH. They performed a three-minute NH with room temper ature dry air achieving twice (IVH2) and three times (IVH3) their RVR. Mean Maximal Expiratory Flow (MEF) in the middle half of Forced Vital Capacity (FCV) (MEF25-75 %) and mean MEF at 25 % of FVC (MEF25 %) are decreased in the asthmatic group IO minutes IVH3 (p=0.02 and <0.002) compared to healthy group. Mean FEVI of both group are not different. Comparing Forced Expiratory Flows variation after NH to baseline intra subject coefficient of variation, sensitivity of the test is 80 % and specificity 100 % when variations of MEF25-75% and MEF 25 % together w ith FEVI variations are considered. This suggests an easy way to adapt an hyperventilation stimulus to size and emphazises the utility of ta king account of MEF25-75 % and MEF25 % in detecting non specific bronc hial hyperreactivity in asthmatic children.