Pulmonary Function Studies in Patients with Upper Airway Obstruction1,2

Abstract

Upper airway obstruction is an important, often unrecognized cause of dyspnea and hypercapnea, even in patients with normal expiratory spirogram. Studies of 9 patients with various causes of upper airway obstruction demonstrated the importance of inspiratory flow in detecting and evaluating this lesion and the value of the flow-volume plot, and direct measurement of the upper airway resistance in defining the dynamic nature of the obstruction.