Upper Airway Resistance Syndrome
Upper Airway Resistance Syndrome or UARS is a sleep condition characterized by airway resistance to breathing during sleep. The primary symptoms include daytime sleepiness and excessive fatigue.
It is difficult to confirm diagnosis, as few sleep testing centers have the proper test equipment to recognize the illness.
Polysomnography (sleep study) with the use of a probe to measure Pes (esophageal pressure) is the gold standard diagnostic test for UARS. Apneas and hypopneas are absent or present in low numbers. Multiple snore arousals may be seen, and if an esophageal probe (Pes) is used, progressive elevation of esophageal pressure fluctuations terminating in arousals is noted. UARS can also be diagnosed using a nasal cannula/pressure transducer to measure the inspiratory airflow vs time signal.
During sleep the muscles of the airway become relaxed. The relaxation of these muscles in turn reduces the diameter of the airway. Typically, the airway of a UARS patient is already restricted or reduced in size, and this natural relaxation reduces the airway further. Therefore, breathing becomes labored. It can be likened to breathing through a coffee straw.
Pathophysiology of UARS is similar to obstructive sleep apnea / hypopnea syndrome in that abnormal airway resistance in the upper airway during sleep leads to unwanted physiologic consequences. Increased upper airway resistance in this disorder does not lead to cessation of airflow (apnea) or decrease in airflow (hypopnea), but instead leads to an arousal secondary to increased work of breathing to overcome the resistance. Repeated and multiple arousals (which the patient is usually unaware of) result in an abnormal sleep architecture and daytime somnolence (sleepiness).
Patients present with snoring and excessive daytime somnolence, and look very much like patients with obstructive sleep apnea.
Treatment for UARS is essentially the same as that for obstructive sleep apnea. (See Sleep apnea)
This includes getting at least 7-8 hours of sleep, avoiding sleeping in supine position (on the back), sleeping with head end of bed elevated and avoiding sedatives, alcohol and narcotics.
Positive airway pressure therapy
This again, is similar to that in obstructive sleep apnea and works by splinting the airway open from the pressure, thus reducing the airway resistance. Reimbursement for the positive airway pressure device (CPAP etc.) may be a concern in certain healthcare models.
Oral appliances to protrude the tongue and mandible (jaw) forward are effective in reducing the airway resistance.
* Adapted from Wikipedia