What is obstructive sleep apnea (OSA)?

What is obstructive sleep apnea (OSA)? - Animation

Obstructive sleep apnea (OSA) occurs when a loss of upper airway patency during sleep results in airway collapse and cessation of airflow for a period greater than ten seconds. A less severe manifestation of sleep apnea is known as sleep hypopnea syndrome (HS). Hypopnea occurs when collapse is extensive but not complete and airflow declines rather than ceases for a period lasting less than ten seconds. OSA and HS are caused by the upper airway being sucked closed by the negative pressure generated upon inspiration. Partial collapse is normal during sleep and is made possible by the relaxation of the upper airways supporting musculature. In sufferers of OSA however, a narrower than normal upper airway predisposes to complete collapse and apnea. Apnea eventually leads to a rise in carbon dioxide and reduction in the bodies oxygen saturation triggering arousal from sleep, contraction of the upper airway muscles, and the resumption of normal breathing. OSA effects an estimated 15 to 20 million Americans and it’s prevalence appears to be increasing in part due to rising obesity which has been identified as a predisposing factor for this condition. OSA is a major source of morbidity and mortality and has been associated with significant sleep deprivation, daytime drowsiness, depression, hypertension and other cardiovascular conditions.