Polysomnography
Participants underwent overnight in-laboratory polysomnography at the
Johns Hopkins Pediatric Sleep Center. Polysomnography was performed
according to standard American
Academy of Sleep Medicine (AASM) guidelines16,17.
Parameters monitored included electroencephalogram, electrooculogram,
submental and pretibial electromyogram, electrocardiogram, nasal airflow
monitored with a pressure transducer and thermistor, thoracic and
abdominal plethysmography, end-tidal CO2 and pulse
oximetry.
Scoring of the polysomnography was performed by a trained sleep
technician and reviewed by a pediatric sleep physician (LS). An
obstructive apnea was defined by the absence of airflow in the nasal and
oronasal airflow with ongoing respiratory effort for at least two breath
cycles. An obstructive hypopnea was defined as a drop-in airflow
(> 30% of baseline) with ongoing respiratory effort for at
least two breath cycles terminated by an arousal from sleep or a ≥ 3%
fall in oxyhemoglobin saturation. OSA was defined as an obstructive
apnea‐hypopnea-index (AHI) of ≥2 events per hr.