Measures of obstructive sleep apnea severity
Hypopnea, hypopnea, OSA, apnea, snoring, Obstructive AHI
EVENTS, EVENT, CENTRAL APNEA
The standard channels recommended by the American Academy of Sleep Medicine (AASM) were used to perform overnight PSG, and data were processed using the Embletta X100 system (Natus Embla Systems, Oakville, ON, Canada). AHI was defined as the number of apnea and hypopnea events divided by total sleep time, expressed as events per hour. Apnea was defined as a reduction in airflow greater than 90% of the pre‐event baseline and occurring for ≥ 10 s measured using a thermocouple signal. Hypopnea events were defined as a reduction in airflow > 30% of the pre‐event baseline and occurring for ≥ 10 s in association with at least a 3% oxygen desaturation or arousal. Hypopnea was considered obstructive if any of the following were present: snoring during the event, an increase in the flattening of the nasal pressure flow, or paradoxical breathing. Obstructive AHI ≥ 15 events/h was considered clinically significant for OSA. Central apneas were defined as apneas occurring without associated respiratory effort lasting ≥ 10 s.Severe OSA was defined as an AHI > 30/h, and very severe OSA was defined as an AHI > 50/h in this study