PFT corner 49 - Noise or upper airway disorder?

Flow oscillations are not specific to OSAS, but are an indication of the presence of some type of upper-airway disorder. Neuromuscular control and coordination of the upper-airway structures for breathing during sleep and wakefulness is not well understood. Many OSAS patients do not present the sawtooth sign (low sensitivity). These patients may fall into the category of patients in whom the upper-airway occlusion during sleep is due to central or neurologic dysfunction that is unrelated to, or concomitant with, the properties of mechanical dysfunction of the upper airway in an awake subject. Regardless of the pathologic mechanisms involved, it is important to recognize that flow oscillations may represent an upper-airway disorder that needs further evaluation.