ABSTRACT
The size and mechanical properties of the upper airway may be important in
understanding the pathophysiology of obstructive sleep apnea (OSA), central
apnea (1), and sudden infant death syndrome (2). Such measurements may
prove useful clinically in diagnosing patients and/or predicting or measuring
response to therapy. Measurements of the upper airway are difficult, however,
because it is a geometrically complex structure subject to considerable vari-
ability with changes in neuromuscular activation, sleep stages, position, and
transmural pressure. Acoustic reflectance represents a unique and noninvasive
technique to ‘‘image’’ the airways, and has been used to assess the properties
of the lower airways, as well as the nose, pharynx, and trachea.
