28A. Obstructive sleep apnoea syndrome

Last updated on June 5, 2021 at 10:57

Definition and epidemiology

Obstructive sleep apnoea syndrome is characterised by repetitive episodes of apnoea or hypopnea that are caused by upper airway obstruction occurring during sleep. These events often result in reductions in blood oxygen saturation and are usually terminated by brief arousals from sleep.

Central sleep apnoea is related but not the same. In central sleep apnoea, there is no obstruction but the respiratory centre stops for short periods of time during the night.

Risk factors

  • Smoking
  • Obesity
  • Family history
  • Nasal congestion
  • Pregnancy
  • Alcohol

Pathomechanism

Apnoea occurs because of upper airway obstruction, usually because the pharyngeal muscles have so low tone that they collapse and close the oropharynx. This causes hypoxaemia and hypercapnia.

Clinical features

Excessive daytime sleepiness is a major presenting complaint in many cases. The patient may also complain of headache, impaired cognitive function, and depression.

The partner may report loud snoring, or interruptions in breathing while sleeping.

Diagnosis and evaluation

Secondary hypertension is a common finding.

Polysomnography is required for diagnosis. On polysomnography we can see decreased O2 saturation, arousal events on EEG, increased pulse pressure, and interruption of sleep phases.

During polysomnography, the apnoea index is measured, which measures the number of apnoeas per hour during sleep. This index determines the severity of the disease.

The oxygen desaturation index can also be measured, which measures the number of episodes of low oxygen saturation per hour during sleep.

Treatment

Treatment involves avoiding risk factors, especially lowing weight. There exist oral appliances which keep the upper airway open during sleep.

In severe cases, CPAP may be used to hold the oropharynx open during night.


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27B. Wilson's disease

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28B. Choreas, Huntington disease

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