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.

<b><i>研究背景:</i></b> 目前尚未针对早产儿开展补氧对睡眠影响的相关研究。<b><i>研究方法:</i></b> 本研究纳入18例经临床观察确诊存在周期性呼吸（periodic breathing）的病情稳定晚期早产儿，其胎龄中位数为36周。分别在室内空气及25%富氧环境空气下对受试者实施多导睡眠监测（Polysomnography）。<b><i>研究结果:</i></b> 补氧未对睡眠阶段分布、睡眠效率、睡眠阶段转换频率、快速眼动（rapid-eye movement, REM）睡眠周期的出现，或频发的自发性觉醒产生影响。周期性呼吸占总睡眠时间的百分比从室内空气环境下的10%（四分位距[interquartile range, IQR] 5~9%）降至补氧环境下的1%（IQR 0~3%）（*p* < 0.001）。此外，中枢性呼吸暂停（central apneas）的每小时发作次数从48次（IQR 32~68）降至23次（IQR 15~32）（*p* < 0.001），每小时最低降幅达3%的氧饱和度下降（oxygen desaturations）事件数从38次（IQR 29~74）降至10次（IQR 5~24）（*p* < 0.001）。在室内空气环境下的非快速眼动睡眠阶段中，存在周期性呼吸时的呼气末二氧化碳（end-tidal carbon dioxide）中位数为5.1（IQR 4.6~6.4）kPa，显著低于稳定呼吸状态下的5.5（4.9~5.9）kPa（*p* < 0.0001）。<b><i>研究结论:</i></b> 对于晚期早产儿，补氧可有效减少周期性呼吸及氧饱和度下降事件的发生，且对睡眠状态无显著影响。本研究结果支持颈动脉体（carotid body）反应过度是早产儿周期性呼吸发病机制的重要环节这一观点。