What is obstructive sleep apnea syndrome (OSAS)?

Updated: Oct 09, 2018
  • Author: Sufen Chiu, MD, PhD; Chief Editor: Caroly Pataki, MD  more...
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Obstructive sleep apnea hypopnea

The pathophysiology of obstructive sleep apnea syndrome (OSAS) is poorly understood. Alterations exist in alveolar ventilation and oxygenation. OSAS is associated with adenotonsillar hypertrophy; however, most youths with adenotonsillar hypertrophy do not experience OSAS. Furthermore, adenotonsillectomy does not appear to resolve OSAS in many children. [6] Upper airway neuromotor dysfunction is possible in the initiation of OSAS. Obesity is now recognized as one of leading risk factors for increasing rates of OSAS. [7]  Snoring is common in OSAS, but some children with OSAS have no snoring reported by their families. [8] Certain medical conditions such as Prader-Willi syndrome or trisomy 21 (Down syndrome) increase the risk for OSAS because of midline deformities such as macroglossia, micrognathia, midface hypoplasia.

Obstructive sleep apnea hypopnea is defined by DSM-5 as evidence from PSG for at least 5 obstructive apnea or hypopneas per hour of sleep and either (1) nocturnal breathing disturbances (snoring, snorting/gasping, breathing pauses during sleep) or (2) daytime sleepiness, fatigue, or nonrefreshing sleep despite sufficient sleep opportunities; these occurrences cannot be explained by another mental disorder or medical condition. Alternatively, it can be diagnosed by PSG evidence of 15 or more obstructive apneas or hypopneas per hour of sleep, regardless of other symptoms. Research criteria used to identify children with OSAS is less stringent, setting the threshold of hypopneas at 1 to 5 events per hour. [8]

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