Diagnosis of Major Airway Obstruction Using the Flow-volume Curve

Abstract

The clinical distinction between upper airway obstruction and lower airway obstruction is not always well defined.The flow-volume curve, a newer test of airway physiology, demonstrates a different characteristic pattern in each type of major airway obstruction and is the easiest way to assess these problems.The purpose of this paper is to explain the efficacy of this test by showing examples of the several basic types of major airway obstruction.In upper airway obstruction below the glottis, flow is constant throughout the initial part of forced maximal expiration. This results in a characteristic plateau or flat curve which is different from the curve in lower airway obstruction.The flow-volume curve is a valuable test in detecting major airway problems.