Sleep apnea syndrome involves pauses in breathing during sleep that result from obstruction of the airway and often occur several hundred times per night. By definition, the pauses in breathing must last at least 10 seconds for sleep apnea syndrome to be suspected.
The following two subgroups are among the most common forms of sleep disordered breathing (SBAS):
- Obstructive sleep apnea syndrome (OSAS) – characterized by obstruction (narrowing) or complete closure of the upper airway during sleep; most common form of sleep apnea (90% of cases).
- Central sleep apnea syndrome (ZSAS) (ICD-10 G47.30: Central sleep apnea syndrome) – characterized by repeated respiratory arrests due to lack of activation of respiratory muscles (episodic inhibition of respiratory drive); 10% of cases
- In addition, there are still various mixed forms of the two groups
The most common is obstructive or mixed sleep apnea.
Central sleep apnea syndrome can be classified as follows:
- Primary central sleep apnea – no other causes; increased CO2 sensitivity; increases in supine position; men are more commonly affected.
- Central sleep apnea with Cheyne-Stokes breathing pattern – in heart failure (cardiac insufficiency), pulmonary hypertension, rarely after cerebral infarction; often increased respiratory drive and decreased CO2; increases in supine position
- Central sleep apnea during altitude exposure – during ascent above 4,000 m; increased respiratory response during hypoxia (lack of oxygen supply to tissues); usually during the first night
- Central sleep apnea in internal and neurological diseases (except Cheyne-Stoke respiration) – predominantly diseases with brainstem lesions, e.g., after encephalitis (inflammation of the brain), cerebral infarction, or in neurodegenerative diseases; disorders of cardiac function (heart function) or renal function (kidney function)
- Central sleep apnea in drug and medication abuse – especially by morphine; after 2 months of use; common with methadone.
- Primary sleep apnea in early childhood – especially in premature infants at birth weight < 2,500 g (25% of cases) and < 1,000 g (about 85% of cases)
Approximately 90% of affected individuals have concomitant airway obstruction (mixed form).
Sex ratio: men are more often affected than women.
Frequency peak: the disease occurs in men mainly in middle age and in women usually after menopause (menopause in women).
Children can also be affected. Here, the cause is usually hyperplasia (enlargement) of the pharyngeal or palatine tonsils.
The prevalence of central sleep apnea is about 4% of the male population and 2% of adult women.
Course and prognosis: Due to the breathing pauses, the affected persons have a lack of oxygen, which makes them sleep poorly. Thus, patients are tired during the day. The fatigue can lead to the compulsion to fall asleep (microsleep). Sleep apnea syndrome results in increased mortality (number of deaths in a given period of time, based on the number of the population in question) from the underlying condition.
