Hypoxic Burden in Children With Sleep-Disordered Breathing: Determinants and Correlates.

Hypoxic burden (HB) is an emerging metric for quantifying intermittent hypoxia associated with sleep apnea, offering potential advantages over traditional measures such as the apnea-hypopnea index (AHI). This study evaluated the distribution and clinical significance of non-respiratory event-specific HB in children and adolescents with habitual snoring, exploring its relationship with sleepiness and other clinical parameters. The data were gathered from 512 children referred for suspected sleep-disordered breathing (SDB), focusing on 380 subjects with available HB data. HB was calculated as the total area under oxygen saturation (SpO₂) curves for events with ≥ 3% oxygen desaturation, with a median value of 1.7% min/h [IQR: 0.6% min/h-4.6% min/h]. Children with moderate-to-severe obstructive sleep apnea syndrome (OSAS) exhibited significantly higher HB than those with mild OSAS or primary snoring (7.5% min/h, 2.7% min/h, and 1.1% min/h, respectively). HB was notably linked to the AHI (rho_s = 0.61), the oxygen desaturation index (rho_s = 0.73), and minimum SpO₂ (rho_s = -0.70). Furthermore, increased HB was observed in obese children and those with tonsillar hypertrophy, underscoring their synergistic impact. These effects were reflected in desaturation depth rather than their duration. In children with primary snoring, HB showed a significant association with parent-reported sleepiness. Specifically, there was a 39% increase in the odds ratio for a modified Epworth sleepiness scale score exceeding 10 for each standard deviation increase in HB (p = 0.040). These findings suggest HB as an independent marker of SDB severity, with potential implications for understanding cognitive deficits linked to SDB in children.