Subjects with hyperreactive airways will demonstrate a response to the inhalation of challenging agents (Methacholine or
Histamine) by displaying signs of airway constriction.
The testing procedure involves executing repeated FVC manoeuvres following the inhalation of pharmacologic agents
according to an established protocol. A subsequent decrease in FEV1 can be used to determine the presence and severity
of bronchial hyperresponsiveness. The PD20 (or PC20, depending on the modality: dose or concentration) is the drug
dosage that leads to a 20% reduction of the FEV1 with respect to the baseline value.
Parameters measured in bronchoprovocation testing include the following: