Sleep-related respiratory disorders G47.39

Sleep apnoea syndrome (acronym SAS) is a sleep-related respiratory disorder, an apnoea syndrome occurring during sleep with(OSAS) or without (SBAS, also known as central SAS) obstruction of the upper airways.

Classification of sleep-related respiratory disorders (SBAS)

• SBAS with obstruction of the upper airways
  • Obstructive snoring (heavy snorer)
  • Obstructive sleep apnea syndrome (OSAS)
  • Upper airway resistance syndrome (UARS): Narrowing of the upper airways during deep sleep without apnea with a significant increase in breathing resistance.
• SBAS without upper airway obstruction (central SAS, hypoventialation syndrome).

About 2 to 4% of adults suffer from obstructive sleep apnea (sleep apnea = breathing pause during sleep with a duration =/>10sec >5x/h). Obstructive sleep apnea is one of the most common widespread diseases. In middle to old age, the incidence in men is between 15% and 19%, in women between 9% and 15%.

Primary snoring is observed in about 25% of adults and in about 50% of people > 65 years.

In OSAS, a collapse of the pharyngeal muscles occurs due to a decrease in the tone of the pharyngeal muscles during sleep, often during REM sleep (REM= rapid eye movement). The activity of the respiratory musculature is maintained, including the respiratory movements. Favouring factors are diseases of the oro-/nasopharynx. These include tonsil hyperplasia, nasal polyps, nasal septal evacuation, macroglossia, retrognathia, enlarged uvula, etc. In children, obstructive sleep apnoea syndrome is most frequently caused by hyperplasia of the pharyngeal or palatine tonsils (Marcus CL et al. 2012).

In SBAS without obstruction (central SAS), the respiratory muscles remain intermittently impaired due to reduced stimulation of the chemoreceptors. Thoracic and abdominal breathing movements are completely absent. About 50% of patients with NYHA stage II suffer from central SAS. In combination with heart failure, this syndrome is known as Cheyne-Stokes respiration.

OSAS:

Loud irregular snoring with respiratory arrest

Increased daytime tiredness/drowsiness with a tendency to fall asleep (microsleep) during monotonous activities (e.g. long driving -7 times higher risk of accidents, working at the PC, reading (Costa G 2017).

Furthermore:

• limited ability to concentrate (hyperactivity)
• reduced hearing ability, usually: conductive hearing loss (Spinosi MC et al. (2017)
• intellectual decline in performance
• Depressive moods, forgetfulness
• Dry mouth in the morning, morning headaches
• Potency disorders (erectile dysfunction)

Central SAS (SBAS):

Usually only slight daytime tiredness/drowsiness with tendency to fall asleep

Often the underlying cardiac or neurological diseases are at the forefront of the clinical symptoms.

"An SBAS" is a "significant cardiovascular risk factor" that is often not directly perceived by the affected person. Complicating symptoms observed are:

• Arterial hypertension resistant to therapy (often without nocturnal blood pressure lowering at 24-hour measurement).
• Nocturnal hypoxia-induced, often bradycardic arrhythmias up to AV block (Xie J et al. 2017).
• Apnea-induced sinus arrhythmia is characteristic (Herold G 2018).
• Worsening of pre-existing heart failure.
• Respiratory global failure
• Increasing risk of myocardial infarction: With an OSA, the risk of myocardial infarction increases 3-fold, and the risk of stroke increases 4-fold.
• Propensity for increased insulin resistance.

Obstructive sleep apnea can also occur in combination with central sleep apnea.

Arterial hypertension can only be described as essential if SAS (sleep-related breathing disorder) is ruled out. SAS is one of the most common causes of secondary hypertension (Wang S et al. 2018)

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2. Herold G et al (2016) Internal Medicine. Herold Publisher SS 346-349
3. Marcus CL et al (2012) Diagnosis and management of childhood obstructive sleep apnea syndrome. Pediatrics 130: e714-55.
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