Assessment of proximal airway obstruction in children by analysis of flow-volume loops.

The usefulness of maximal expiratory and inspiratory flow-volume (F-V) loops was assessed in ten children with clinical evidence of tracheal or laryngeal obstruction. Normal values from 514 healthy children are presented. Measurement of maximal flow, and expiratory/inspiratory flow ratios and observation of the characteristic contours of the F-V loops distinguished between proximal and peripheral airways obstruction in all cases. Most children over the age of 7 years could perform the test adequately. F-V loop analysis is a valuable technique in the assessment of the child with proximal airway obstruction. Unlike endoscopic and radiological investigation, it measures the functional rather than the anatomical degree of obstruction, and provides a simple non-invasive way of monitoring the response to treatment.