Sleep Apnea Syndrome
The Sleep Apnea Syndrome can be divided in two classes:
1. Central Sleep Apnea Syndrome
It is due to the lack of drive of the central nervous system (CNS) to the respiratory muscles, or failure of the respiratory muscle itself, causing the interruption of breathing during the sleep
2. Obstructive Sleep Apnea Syndrome
During the sleep of the patients with Obstructive Sleep Apnea Syndrome (OSAS), the muscles supporting the upper airway tissue become relaxed and the upper airway becomes smaller. Especially when sleeping, the patient¡¯s mandible and tongue pull back and block the collapsed airway, so the breathing becomes more difficult.
When the brain senses the reduction of oxygen saturation, there will be an arousal mechanism to facilitate the forced breathing so the muscles of the laryngopharynx restore the tension in order to open the upper airway, and the breathing returns to normal condition, the patient can sleep again. This arousal time is short, most of the people do not notice. This kind of sleep cycle which can disturb the sleep could happen several times in the night, in some severe patients it can even occur more than 100 times. Most of the patients with Obstructive Sleep Apnea Syndrome (OSAS) snore and have breathing interruption, they awake often and have nocturnal polyuria (possibly due to reduced level of anti-diuretic hormone), memory reduction, easy to be weary in the daytime, somnolence and other related syndromes. These patients shall avoid drinking alcohol, taking hypnotic or tranquilizer before going to bed, otherwise would cause more upper airway collapse.
What is the Apnea Hypopnea Index?
The definition of the sleep apnea is that the breathing interruption for at least 10 seconds. The Apnea Hypopnea Index (AHI or RDI) means the breathing interruption times occurred in an hour.
The standards established by the American Academy of Sleep Medicine (AASM):
The index of less than 5 times per hour is considered as negative,
Between 5-15 times is mild degree,
Between 15 and 30 times is moderate degree,
Over 30 times is severe degree of Obstructive Sleep Apnea Syndrome.
Diagnosis of the Sleep Apnea Syndrome
When the patient suspect himself or his family to have Sleep Apnea Syndrome, it is suggested to let the physicians of the Sleep Disorders Center to make a detailed inquiry and examination, and schedule the Polysomnography at the Sleep Lab of the Sleep Disorders Center, in order to make sure if the patient suffers the Sleep Apnea Syndrome, and its type and severity. First it is necessary to get a correct diagnosis and find the reason in order to organize a complete treatment.
