P009 Time spent with SpO2 below 90% during Sleep is Greater in Children with Down syndrome and OSA than in Typically Developing Children

BACKGROUND: Children with Down syndrome (DS) have a higher predisposition to obstructive sleep apnoea (OSA) compared to typically developing (TD) children. Children with DS have more frequent dips <90% compared with TD children matched for age, sex and OSA severity. Intermittent hypoxia with repeated desaturations and resaturations is associated with cognitive impairment in children. New methods which calculate the time spent with SpO2 <90% have identified an association with cardiac dysfunction in adults with OSA. We aimed to determine if children with DS and OSA spent longer with SpO2 <90% during sleep compared with TD children. METHODS: 44 children with DS (3-19 y) and age, sex and OSA severity matched TD children underwent overnight polysomnography. Time spent with SpO2 <90% as a percentage of total sleep time (%TST) was calculated. SpO2 nadir when <90% was recorded. RESULTS: SpO2 fell <90% in 32 (73%) children with DS and 15 (34%) TD children. The %TST spent with SpO2 <90% was higher in the DS group (median [IQR] 0.029% [0.004, 0.114]) compared with the TD group (0.000% [0.000, 0.020]; p<0.001). There was no difference in SpO2 nadir between the groups (DS mean±sem 84%±1.1%; TD 85%±1.1) when the SpO2 fell <90%. CONCLUSION: Twice as many children with DS experienced periods of oxygen desaturation below 90% as did TD children matched for age, sex and OSA severity. Although as a %TST, the time spent <90% was small, different physiologically-based metrics to characterise OSA severity and the consequences of recurrent hypoxia in children may be merited.