Wong W, et al. – The clinicians undertook this study to determine the prevalence of sleep–associated hypoventilation independent of obstructive sleep apnea (OSA) in children with Down syndrome (DS). They discovered that mildly elevated ETCO₂ in the absence of OSA was common in these children. This link might reflect underlying differences in autonomic control of ventilation in children with DS.

Methods

• This study consisted of children with DS under 18 years of age undergoing polysomnography at a tertiary care paediatric hospital during a 2–year period.
• Exclusion criteria were as follow: those requiring oxygen or positive–pressure ventilation; with tracheostomy, baseline hypoxia, unrepaired cyanotic heart disease, pulmonary hypertension, and cerebral palsy; or OSA with >5 obstructions/hour.

Results

• In total 86 children met inclusion criteria.
• During sleep, 68 (79%) had ETCO₂values >50 mm Hg.
• 37 (43%) ranged 50–55 mm Hg, and 12 (14%) met American Academy of Sleep Medicine criteria for hypoventilation of ETCO₂ >50 mm Hg for >25% of total sleep time (TST).
• Average pulse–oximetry saturation (SpO₂) values during sleep were 97.8% (SD ±1; range: 95.1–99.9).
• Average percentage of TST with SpO₂ >92% was 99.89%.