Overnight PSG study and scoring procedures were reported previously
by our laboratory.10 Briefly, all children in groups 2 and 3 underwent
nocturnal PSG monitoring (SensorMedics Inc., Yorba Linda, Calif,
USA). Subjects reported to the sleep laboratory at 8:30 PM, were discharged
at 7:30 the following morning, and were encouraged to maintain
their customary daily routine and take medications as usual. Sleep and
wake stages, arousals, and awakenings were scored as recommended
with the appropriate modifications for children. The arousal index (AI)
was calculated as the number of arousals or awakenings per hour of
sleep. Obstructive apnea was defined as paradoxical breathing for at
least 2 respiratory cycles with complete cessation of nasal airflow.
Obstructive hypopnea was scored when the paradoxical breathing was
accompanied by a reduction of at least 50% in airflow, resulting in either
an arousal or an oxygen desaturation of at least 4%. The respiratory disturbance
index (RDI) was defined as the number of apneas and hypopneas
per hour of sleep. The average waiting time for a PSG study was
approximately 7 weeks. Following a PSG diagnosis, treatment alternatives
included adenotonsillectomy and follow-up visits.