Anatomical Optical Coherence Tomography of the Human Upper Airway

Abstract

Endoscopic visualization of the internal surface of hollow organ systems is widely used in medical practice. Examples include endoscopy of the urinary tract, gastrointestinal tract, and upper and lower respiratory tracts. Although valuable for visualizing the internal anatomy, a limitation of endoscopy has been the inability, to date, to easily quantify internal dimensions during these examinations. Such objective measurements would be particularly valuable in understanding the behavior of the human airway. Repetitive collapse of the upper airway during sleep is the hallmark of obstructive sleep apnea, a common condition affecting 2%–4% of middle-aged adults [1]. Despite three decades of research, the pathogenesis of obstructive sleep apnea remains incompletely understood. The prevailing view is that patients with obstructive sleep apnea have smaller pharyngeal airways and higher pharyngeal resistances, requiring a compensatory increase in pharyngeal muscle activity to maintain upper airway patency during wakefulness. When such patients sleep, state-related reductions in pharyngeal muscle activity remove this essential compensatory mechanism and airway collapse ensues. These episodes of partial or complete upper airway obstruction are terminated by brief arousals from sleep, often lasting only seconds and not consciously perceived by the patient but enough to disrupt sleep and be responsible for the excessive daytime sleepiness that characterizes the obstructive sleep apnea–hypopnea syndrome.