THURSDAY, May 5 (HealthDay News) -- In children with obstructive sleep apnea syndrome (OSAS), sleep-disordered breathing improves after adenotonsillectomy possibly due to decreases in the sympathetic activity of the autonomic nervous system, according to a study published in the May issue of Chest.
Hiren V. Muzumdar, M.D., from the Children's Hospital at Montefiore in New York City, and colleagues measured changes in heart rate variability (HRV) in 18 children with an average age of 4.9 years with OSAS and adenotonsillar hypertrophy who underwent adenotonsillectomy and had a subsequent improvement in OSAS. Participants underwent polysomnography before and after adenotonsillectomy, and changes in heart rate (HR) and HRV time and frequency were analyzed in two-minute epochs free of respiratory events during light, deep, and REM sleep.
The investigators found that the apnea-hypopnea index decreased from an average of 31.9 events/hour to 4.1 events/hour after adenotonsillectomy. The average HR decreased in all stages of sleep after adenotonsillectomy: from 99.8 to 80.7 beats/minute in light sleep, from 100.2 to 80.5 beats/minute in deep sleep, and from 106.9 to 87.0 beats/minute in REM sleep. The average ratio of low-frequency to high-frequency band power decreased in all stages of sleep after adenotonsillectomy: from 1.6 to 0.6 in light sleep, from 1.2 to 0.5 in deep sleep, and from 3.0 to 1.4 in REM sleep.
"This study demonstrates that improvement in OSAS following adenotonsillectomy in children is associated with changes in autonomic balance as shown on HRV analysis," the authors write.
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