Supplementary Material for: Supplemental Oxygen Treats Periodic Breathing without Effects on Sleep in Late-Preterm Infants

<b><i>Background:</i></b> The effect of supplemental oxygen on sleep has not been studied in preterm infants. <b><i>Methods:</i></b> We studied 18 stable late-preterm infants with observed periodic breathing at a median gestational age of 36 weeks. Polysomnography was performed on room air and on 25% oxygen-enriched ambient air. <b><i>Results:</i></b> Supplemental oxygen did not affect sleep stage distribution, sleep efficiency, the frequency of sleep stage transitions, the appearance of rapid-eye movement (REM) sleep periods, or the high number of spontaneous arousals. The percentage in periodic breathing out of total sleep time decreased from 10% (interquartile range [IQR] 5–9%) on room air to 1% (IQR 0–3%) (<i>p</i> &lt; 0.001) on supplemental oxygen. Also, the number of central apneas decreased from 48 (IQR 32–68) to 23 (IRQ 15–32) per hour (<i>p</i> &lt; 0.001), and the number of oxygen desaturations of a minimum 3% from 38 (IQR 29–74) to 10 (IQR 5–24) per hour (<i>p</i> &lt; 0.001). On room air in non-REM sleep, the median end-tidal carbon dioxide values were systematically lower during periodic breathing at 5.1 (IQR 4.6–6.4) kPa than during stable breathing at 5.5 (4.9–5.9) kPa (<i>p</i> &lt; 0.0001). <b><i>Conclusions:</i></b> In late-preterm infants, supplemental oxygen effectively reduces periodic breathing and the number of oxygen desaturations while having no significant effect on sleep. The results support the importance of carotid body over-reactivity on the genesis of periodic breathing in preterm infants.