The American review of respiratory disease
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Mild excerice in 7 patients with upper airway obstruction but without diffuse lung disease caused a mean decrease in arterial oxygen tension of 11 mm Hg. Exercise hypoxemia disappeared after surgical removal of obstruction in 3 patients tested. ⋯ Analysis of mechanics of air flow through an orifice suggests that exertional dyspnea is caused by manifold increase of airway resistance during exercise; acute respiratory failure might be precipitated by further minimal reduction in airway lumen once it has reached a diameter of 8 mm. Clinicians should be alert to the possibility of upper airway obstruction in any symptomatic patient who has had tracheal intubation or in patients with obscure wheezing, especially on exercise.