0891 Cardiovascular Control is Impaired in Children With Down Syndrome and Sleep Disordered Breathing

Abstract

Abstract Introduction Children with Down Syndrome (DS) are at increased risk for sleep disordered breathing (SDB). In typically developing (TD) children, SDB is associated with adverse cardiovascular effects including elevated heart rate and blood pressure and impaired autonomic control. The aim of this study was to compare the cardiovascular effects of SDB in children with DS to those of TD children with and without SDB. Methods 44 children with DS (3-18 y) were age and gender matched with 44 TD children without SDB (TD-) and with TD children with matched severity of SDB (TD+). Height, weight and blood pressure were measured and BMI, systolic and diastolic z-scores calculated. Heart rate variability (HRV) was calculated for 2 min artefact free epochs overnight. Power spectral density for the low frequency (LF), high frequency (HF), total power (TP) and the LF/HF ratio (sympathovagal balance) were calculated. Data were compared between groups with Kruskal-Wallis one-way ANOVA. Results Wake heart rate, systolic and diastolic z-scores were not different between groups. LF/HF was higher in the DS group compared to both TD+ (p<0.05) and TD- (p<0.01) in wake and total sleep time. During total sleep HF power was lower in DS compared to TD+ (p<0.01). In N2 TP and HF were lower and LF/HF higher in DS compared to both TD+ (p<0.01) and TD- (p<0.05). In N3 HF was lower in DS compared to TD+ (p<0.05) and LF/HF was higher compared to both TD+ and TD- (p<0.001 for both) and in REM LF/HF was higher compared to TD+ (p<0.01). Conclusion In children with DS and SDB, autonomic cardiovascular control is impaired compared to TD children matched for SDB severity and to non-snoring TD children. Our findings demonstrate significantly reduced parasympathetic activity (reduced HF power) and increased sympathovagal balance, that may contribute to increased risk of cardiovascular disease later in life. Support This study was funded by the Jack Brockhoff Foundation.