Nocturnal hypoventilation in Down syndrome children with or without sleep apnea

There is a high prevalence of obstructive sleep apnea (OSA) in children with Down syndrome (DS), sometimes associated with alveolar hypoventilation.

To compare transcutaneous partial pressure of carbon dioxide (PtcCO₂ ) and pulse oximetry (SpO₂ ) in children with DS and in control children with OSA.

This retrospective case-control study involved children followed in Trousseau Hospital (Paris) Sleep Center. Polysomnography (PSG) recordings and clinical files of children with DS were reviewed to identify clinical signs of OSA and comorbidities associated with DS. Controls were children who presented with OSA of ENT origin without other comorbidities (exceptions: two overweight, one obese, and three with well-controlled asthma). DS subjects and controls were matched for age and apnea hypopnea index.

There were 28 children in each group. Mean PtcCO₂ during sleep was significantly higher in patients with DS compared to controls (44 mm Hg vs 42 mm Hg, P = .001). Five (21%) patients with DS met the American Academy of Sleep medicine criteria for hypoventilation, compared to one (4%) in the control group. The mean PtcO₂ during sleep was significantly lower in patients with DS (77 mm Hg vs 82 mm Hg, P = .003).

This is the first study to compare nocturnal gas exchange in children with DS to a control group of children with similar OSA. Our data demonstrate that children with DS have increased PtcCO₂ regardless of the presence of OSA and its severity. This may be due to respiratory muscle hypotonia and/or ventilatory control alteration in patients with DS.