Obstructive Sleep Apnea syndrome or OSAS is a sleep disorder involving recurrent episodes of cessation of breathing or decrease in airflow for 10 seconds or more while sleeping.
People with OSAS may also experience hypopnea, which is described as episodes wherein the breathing becomes abnormally slow and shallow. OSAS arises due to an obstruction of the airways.

Obstructive sleep apnea [OSA] is always confirmed by doing a sleep study [Polysomnography] A patient is said to be suffering from OSA if he has 5 or > episodes of apnea / hypopnea associated with oxygen desaturation in 1 hour of sleep.


Apnea is a condition in which patient stops breathing for 10 sec. or more.


Hypopnea is a condition in which patient is breathing at 50% or less of his lung capacity.


Apnea Hypopnea Index - Summation of Apnea and Hypopnea in 1 hour of sleep.


Respiratory Distress Index - Summation of Apnea, Hypopnea and Arousals in 1 hour of sleep.