Sleep Apnea, Obstructive



  • Obstructive sleep apnea (OSA) is defined as repetitive episodes of cessation of airflow (apnea) through the nose and mouth during sleep due to obstruction at the level of the pharynx.
    • Repetitive apneas produce sleep disruption, leading to excessive daytime sleepiness (EDS).
    • Associated with oxygen desaturation and nocturnal hypoxemia
  • System(s) affected: cardiovascular; nervous; pulmonary
  • Synonym(s): sleep apnea syndrome; nocturnal upper airway occlusion



  • The estimated prevalence rated of moderate to severe sleep-disordered breathing has substantially increased over the last two decades. The current prevalence is 10% among 30- to 49-year-old men and 17% among 50- to 70-year-old men. In women, the prevalence is 3% among 30- to 49-year-old women and 9% among 50- to 70-year-old women (1).
  • Highest in obese/hypertensive patients

Etiology and Pathophysiology

OSA occurs when the naso- or oropharynx collapses passively during inspiration. Anatomic and neuromuscular factors contribute to pharyngeal collapse, which leads to hypoxic arousal.

  • Anatomic abnormalities, such as increased soft tissue in the palate, tonsillar hypertrophy, macroglossia, and craniofacial abnormalities, predispose the airway to collapse by decreasing the area of the upper airway or increasing the pressure surrounding the airway.
  • During sleep, decreased muscle tone in the naso- or oropharynx contributes to airway obstruction and collapse.
  • Upper airway narrowing may be due to the following:
    • Obesity, redundant tissue in the soft palate
    • Enlarged tonsils/uvula or a low soft palate; large/posteriorly located tongue
    • Craniofacial abnormalities or neuromuscular disorders
    • Alcohol/sedative use before bedtime

Risk Factors

  • Obesity (strongest risk factor)
  • Age >40 years
  • Alcohol/sedative intake before bedtime
  • Smoking
  • Nasal obstruction (due to polyps, rhinitis, or deviated septum)
  • Anatomic narrowing of nasopharynx
  • Hypothyroidism
  • Neurologic syndromes (e.g., muscular dystrophy, cerebral palsy)

General Prevention

Weight control and avoidance of alcohol and sedatives at night can help.

Commonly Associated Conditions

  • Hypertension
  • Obesity
  • Daytime sleepiness
  • Metabolic syndrome


  • Cardiac arrhythmias
  • Cardiovascular disease
  • Congestive heart failure
  • Pulmonary hypertension
  • Nasal obstructive problems

There's more to see -- the rest of this topic is available only to subscribers.