Oxygen desaturation during sleep in infants and young children with congenital heart disease

Oxygen saturation (Sao₂) during sleep and pulmonary functions were evaluated in 19 infants with congenital heart disease, aged 6±4 months, and in 11 normal infants, aged 8±5 months, to determine whether infants with congenital heart disease have more frequent oxygen desaturation during sleep and, if so, its relationship to underlying pulmonary function. Infants with congenital heart disease were classified as acyanotic (n=11) or cyanotic (n=8) on the basis of their aortic Sao₂ at the time of cardiac catheterization (greater or less than 90% Sao₂). Pulmonary function tests included respiratory rate, functional residual capacity, total respiratory system compliance, and maximal flows at functional residual capacity. Significant differences were found in the values for the lowest Sao₂ of each 5-minute epoch (Sao_2L) averaged during the entire sleep time (normal 94%±2%, acyanotic 90%±3%, and cyanotic 74%±4%; p<0.01). The three groups also differed significantly in frequency distributions of percentage of total sleep time with Sao_2L less than 90% (Sao_2%T) (normal 10%±17%, acyanotic 36%±34%, and cyanotic 97%±4%; p<0.05). Compared with the control group, the acyanotic group had a higher respiratory rate (66±19 breaths/min vs 35±6 breaths/min; p<0.01), a lower tidal volume (65%±29% predicted vs 105%±18% predicted; p<0.01), and a lower total respiratory compliance (59%±18% predicted vs 106%±30% predicted; p<0.01). A negative correlation existed between Sao_2%T and aortic Sao₂ (R²=0.64; p<0.01). We conclude that oxygen desaturation occurs during sleep in infants with congenital heart disease; the presence of desaturation appears to be related to the initial degree of hypoxemia and the presence of abnormal pulmonary function.