Reference value for expiratory time constant calculated from the maximal expiratory flow-volume curve

摘要

Visual representation of maximal expiratory flow at 50% (MEF ) and 25% (MEF ) of forced vital capacity (FVC). The MEF and MEF are shown as red points located along the descending limb of the maximum expiratory flow-volume (MEFV) curve. The expiratory time constant (RC ) is calculated as the reciprocal of the slope of the line passing through MEF and MEF