Study objectives: To describe polysomnographic parameters and their clinical correlates in a referred sample of children with sickle cell disease (SCD).
Methods: This was a retrospective medical record review of 55 consecutive children aged 2-18 years with SCD (hemoglobin [Hb] SS and Hb SC genotypes) undergoing polysomnography for evaluation of sleep disordered breathing. Polysomnography values were compared between SCD genotypes, 4 age groups, and adenotonsillectomy status using descriptive and nonparametric statistics.
Results: Obstructive sleep apnea (OSA) was diagnosed in 38/55 (69%) children. Polysomnographic parameters differed significantly between Hb SS and Hb SC genotypes only on arterial oxyhemoglobin saturation (SpO2; 95.2 +/- 3.8 vs. 98.0 +/- 0.8, respectively, p < 0.01) and percent of sleep time below SpO2 90% (T90; 8.0 +/- 22.0 vs. 0.01 +/- 0.02, respectively, p < 0.05). Increasing age was associated with decreasing SpO2 (rho = -0.282, p < 0.05), obstructive apnea-hypopnea index (OAHI; rho = -0.364, p < 0.01), total arousal index (rho -0.272, p < 0.05) and respiratory arousal index (rho = -0.349, p < 0.01). Periodic limb movements in sleep (PLM) averaged 4.7 +/- 8.8/h, with a PLM index > 5/h in 5/17 children without OSA. Post- adenotonsillectomy, 8/10 children had OSA, but compared to untreated OSA-positive children they had a lower mean OAHI (4.4 +/- 5.5 vs. 8.9 +/- 12.5) and a lower T90 (1.6 +/- 4.2 vs. 9.2 +/- 24.9).
Conclusions: Both OSA and PLMs were common in children with SCD. Children with Hb SS experienced more severe nocturnal oxygen desaturation than did those with Hb SC. Post-adenotonsillectomy, most children had OSA, although they experienced fewer obstructive respiratory events and less severe nocturnal oxygen desaturation than did untreated OSA-positive children.