Post-Bronchodilator FEV1/FVC Ratio < 0.70
The persistent inability to forcefully exhale a normal proportion of lung capacity, confirming irreversible airway obstruction.
Description
Similar to standard spirometry, the patient performs forced exhalation maneuvers after taking a short-acting bronchodilator. This clinical standard evolved to differentiate asthma from fixed obstructive diseases. It measures the absolute limit of lung function once reversible spasms are relieved.