Definition

1. Syndrome in which repetitive episodes of cessation of airflow or decreases in airflow occur during sleep in the presence of continued respiratory effort (obstructive sleep apnea). Cessation of airflow without respiratory effort is seen in central sleep apnea. A combination of these two events is seen in mixed apneas.
2. The Apnea/Hypopnea Index (AHI) is a method of quantifying the severity of the sleep disordered breathing. It is the sum of all respiratory events occurring over a full night divided by the total sleep time recorded in hours. An AHI>5/hour is considered abnormal in most populations, and in the appropriate clinical setting, defines obstructive sleep apnea syndrome (OSAS).
3. Recent studies have found an incidence of OSAS of approximately 4% in middle aged US males, and approximately 2% of females. Children and infants may also be afflicted. Familial clustering has been reported.
4. Risk factors for OSAS:
   • obesity
   • advancing age
   • snoring
   • sleep deprivation
   • ethanol and sedative/hypnotic medications
   • hypothyroidism
   • general anesthetics
   • certain antihypertensive agents (methyldopa, propranolol)
   • COPD
   • ribcage and neuromuscular abnormalities
   • CNS disorders
   • nasal obstruction
   • tonsillar/adenoidal hypertrophy
   • acromegaly
   • micro and retrognathia
   • macroglossia
   • lymphoma
   • Shy-drager Syndrome
   • amyloidosis
   • congenital syndromes