Sleep Apnea, Obstructive

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Basics

Description

  • 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.
    • Apneas often terminate with a snort/gasp.
    • Repetitive apneas produce sleep disruption, leading to excessive daytime sleepiness (EDS).
    • Associated with oxygen desaturation and nocturnal hypoxemia
    • Usual course is chronic.
  • System(s) affected: cardiovascular; nervous; pulmonary
  • Synonym(s): sleep apnea syndrome; nocturnal upper airway occlusion

Epidemiology

Incidence
  • Predominant age: middle-aged men and women
  • Predominant sex: male > female (2:1)

Prevalence
  • Up to 15% in men, 5% in women
  • Prevalence is higher 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
    • Low soft palate
    • Large/posteriorly located tongue
    • Craniofacial abnormalities
    • 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 (e.g., tonsillar hypertrophy, macroglossia, micrognathia, retrognathia, craniofacial abnormalities)
  • Acromegaly
  • Hypothyroidism
  • Neurologic syndromes (e.g., muscular dystrophy, cerebral palsy)

General Prevention

Weight control and avoidance of alcohol and sedatives at night can help to prevent airway collapse.

Commonly Associated Conditions

  • Common
    • Hypertension
    • Obesity
    • Daytime sleepiness
    • Metabolic syndrome
  • Rare
    • Cardiac arrhythmias
    • Cardiovascular disease
    • Congestive heart failure
    • Pulmonary hypertension
    • Nasal obstructive problems

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