Table. 10—

Lung function parameters capable of differentiating extrathoracic from intrathoracic obstruction

Extrathoracic obstructionIntrathoracic obstruction
FixedVariable
PEFDecreasedNormal or decreasedDecreased
MIF50DecreasedDecreasedNormal or decreased
MIF50/MEF50∼1<1>1

  • PEF: peak expiratory flow; MIF50: maximum inspiratory flow at 50% of forced vital capacity (FVC); MEF50: maximum expiratory flow at 50% of FVC.