The different flow pattern in tracheal stenosis, bronchospasm and emphysema.

We can conclude that the combination of high FEV2/1 index and a "peak-flow-less" flow-volume loop is characteristic for the presence of proximal airway stenosis and is a reliable means for differentiation against bronchospasm and emphysema. In comparison, the measurement of airway resistance, FEV1 alone, inspiratory shift of mid-breathing level etc., indicate only the presence of airway obstruction, but fail to give specific information for functional differentiation of bronchial obstruction and morphological evidence of proximal airway stenosis.