obscure focal findings, and upper airway sounds are often transmitted to lower airways The ratio of inspiratory to expiratory phase of respiration, normally 1:1, can be useful in distinguishing an upper from lower respiratory tract obstructive causes of respiratory distress Respiratory distress from upper airway disease usually results from difficulty of inward air movement The inspiratory phase is often increased relative to the expiratory phase Lower airway processes often impede outward air movement and may result in a prolonged expiratory phase Absence of wheeze in a child with continued or worsening respiratory distress may represent severe obstruction and should not be considered reassuring but rather may herald impending respiratory arrest