Prospective polysomnographic analysis of obstructive sleep apnea in Down syndrome

Objectives: To investigate obstructive sleep apnea (OSA) in a consecutively encountered, nonselected population of young patients with Down syndrome using standard overnight polysomnography and to determine the effects of therapy. Methods: In a population of patients seen for routine developmental evaluations, 9 boys and 10 girls were studied using standard overnight polysomnography. Results: Using pediatric standards, OSA was found in 79% of the subjects (95% confidence interval, 54%-94%), with a median apnea index of 3 events per hour (interquartile range, 2-5), a median apnea-hypopnea index of 6 events per hour (interquartile range, 3-8), and a median arterial oxygen saturation (SaO(2)) low point of 88% (interquartile range, 84%-90%). Higher body mass index was significantly associated with a higher apnea index and a lower SaO(2) level, and there was a significant inverse relationship between age and the lowest SaO(2) value as well as a possible association between sleep-related symptoms at the time of diagnosis and the lowest SaO(2) value. In addition, patients with OSA had a significantly higher movement arousal index than those without OSA. Conclusions: Using rigid polysomnographic standards, this pilot study revealed OSA in a high percentage of young subjects with Down syndrome and an association between OSA and obesity, age, and poor sleep quality. These findings justify larger and more detailed population studies to further define clinical factors that are concomitant with OSA in Down syndrome and to improve therapy.