<prompt> Apnea- hypopnea index ___ is used for diagnosis of OSAHS in absence of symptoms?5 episodes hr10 episodes hr15 episodes hr20 episodes hr  <response>: OSAHS is defined on the basis of nocturnal and daytime symptoms as well as sleep study findings. Diagnosis requires the patient to have 1 either symptoms of nocturnal breathing disturbances snoring, snoing, gasping, or breathing pauses during sleep or daytime sleepiness or fatigue that occurs despite sufficient oppounities to sleep and is unexplained by other medical problems; and 2 five or more episodes of obstructive apnea or hypopnea per hour of sleep the apnea-hypopnea index , calculated as the number of episodes divided by the number of hours of sleep documented during a sleep study. OSAHS also may be diagnosed in the absence of symptoms if the AHI is 15 episodesh. Each episode of apnea or hypopnea represents a reduction in breathing for at least 10 s and commonly results in a 3 drop inoxygensaturation andor a brain coical arousal. OSAHS severity is based on the frequency of breathing disturbances AHI, the amount of oxyhemoglobin desaturation with respiratory events, the duration of apneas and hypopneas, the degree of sleep fragmentation, and the level of daytime sleepiness or functional impairment. Obstructive Sleep ApneaHypopnea Syndrome OSAHS: Quantification and Severity Scale Apnea-hypopnea index AHIa:Number of apneas plus hypopneas per hour of sleep Respiratory disturbance index RDI:Number of apneas plus hypopneas plus RERAs per hour of sleep Mild OSAHS:AHI of 5-14 eventsh Moderate OSAHS:AHI of 15-29 eventsh Severe OSAHS:AHI of 30 eventsh aEach level of AHI can be fuher quantified by level of sleepiness and associated hypoxemia. 