Apneas during sleep are defined as airflow cessation, whereas in case of hypoapneas airflow decreases in airways from 30 to 50 percent in the airways and can last up to 10 seconds or more in adults (mostly 10 to 30 seconds). Consequently blood oxygen saturation levels usually decrease. There are two major breathing disorders during sleep:

a) Obstructive sleep apnea (OSA) is a breathing disorder where there is a continuous complete (apnea) or semi-complete (hypopnea) obstruction of airflow in the upper respiratory tract during sleep, usually resulting in short reactions of awakening during sleep. Long lasting apneas or hypopneas with a greater decreas of blood oxygen levels are common during REM (Rapid Eye Movement) phases. Saturation returns to the primary level when a person begins to breathe again. Obstructive Sleep Apnea/Hypopnea during Sleep represent 80 percent of all breathing disorders during sleep. Problems arising from the above mentioned are also known as OSAH syndrome.

b) Central forms of apneas during sleep are known to be primary and secondary. In case of primary forms the cause remains unknown whereas in case of secondary apneas, the cause can be the malfunction of the brain stem (due to neurologic illness – degenerative, demyelinating, neoplastic, vascular or traumatic etiologies), heart or kidney malfunction, or it can be a consequence of drug intake (long-acting opioids) or drug abuse. A number of problems arising from the aforementioned are also known as the CSAHS – Central Sleep Apnea/Hypopnea during Sleep). This syndrome is a consequence of transient absence of the breathing impulse due to the malfunction of the respiratory center in the brain stem (1,2,3,4).

Next to the mentioned forms, according to international guidelines, there are also the so called Cheyne-Stokes respiration and Obesity Hypoventilation syndrome (2).

According to some researchers, 80 to 90 percent of OSAH syndroms remain undiagnosed (11).

Financial burden or medical cost due to untreated OSA syndrome is estimated at 3.4 billion USD, without the costs due to absenteeism or accidents at work and in traffic (6).