Division of Neonatology, Department of Pediatrics, University of Miami Miller School of Medicine, Miami, FL, USA.
Neonatology. 2018;113(1):69-74. doi: 10.1159/000481395. Epub 2017 Oct 31.
Hypoxemia episodes (HE) occur frequently in ventilated preterm infants and hinder the achievement of arterial oxygen saturation (SpO2) targets. These episodes may increase the risk for retinopathy of prematurity and neurodevelopmental disability. There are no data on the variation in HE and SpO2 targeting between day and night.
The aim of this study was to evaluate the difference between day and night on the frequency and severity of HE and achievement of SpO2 targets.
Twenty-four mechanically ventilated preterm infants with ≥4 episodes of SpO2 <75% over an 8-h period were enrolled. The fraction of inspired oxygen (FiO2), SpO2, and ventilator parameters were recorded over 24 h. Data from the day (9 a.m. to 5 p.m.) were compared to the night (9 p.m. to 5 a.m.) for the frequency of HE and proportion of time within and outside the target SpO2 range (90-95%).
The frequency of severe HE (SpO2 <75, ≥20 s) and prolonged severe HE (SpO2 <75, ≥60 s) was lower during the night compared to the day (1.6 ± 1.0 vs. 2.4 ± 1.3 episodes/h, p = 0.008, and 0.53 ± 0.35 vs. 0.90 ± 0.54 episodes/h, p = 0.018). There was no difference in mean episode duration. The frequency and duration of mild HE (SpO2 <85, ≥20 s) were lower during the night compared to the day (5.9 ± 2.7 vs. 7.1 ± 2.5 episodes/h, p = 0.003, and 72 ± 15 vs. 87 ± 25 s, p = 0.01, respectively). The proportion of time in severe hypoxemia (SpO2 <75%) was smaller, whereas time in hyperoxemia (SpO2 >95%) was greater, during the night compared to the day. The mean FiO2 did not differ between day and night.
In this group of infants with frequent HE, nighttime was associated with fewer episodes when compared to daytime. This is likely due to less handling and sensory stimulation during the night. The increase in time spent with hyperoxemia during the night is likely to be due to more tolerance of high SpO2 with less proactive weaning of FiO2.
低氧血症发作（HE）在接受通气治疗的早产儿中经常发生，且会阻碍动脉血氧饱和度（SpO2）目标的实现。这些发作可能会增加早产儿视网膜病变和神经发育障碍的风险。目前尚无昼夜之间 HE 和 SpO2 目标设定变化的数据。
本研究旨在评估白天和夜间 HE 发作的频率和严重程度以及 SpO2 目标实现情况的差异。
共纳入 24 例在 8 小时内出现≥4 次 SpO2＜75%的机械通气早产儿。记录吸入氧分数（FiO2）、SpO2 和呼吸机参数，连续 24 小时监测。比较白天（上午 9 点至下午 5 点）和夜间（晚上 9 点至凌晨 5 点） HE 发作的频率以及在目标 SpO2 范围内（90-95%）和范围外的时间比例。
与白天相比，夜间严重 HE（SpO2＜75，≥20 s）和长时间严重 HE（SpO2＜75，≥60 s）的发作频率较低（1.6±1.0 次/小时比 2.4±1.3 次/小时，p=0.008，0.53±0.35 次/小时比 0.90±0.54 次/小时，p=0.018）。平均发作持续时间无差异。与白天相比，夜间轻度 HE（SpO2＜85，≥20 s）的发作频率和持续时间较低（5.9±2.7 次/小时比 7.1±2.5 次/小时，p=0.003，72±15 s 比 87±25 s，p=0.01）。夜间严重低氧血症（SpO2＜75%）的时间比例较小，而高氧血症（SpO2＞95%）的时间比例较大。白天和夜间的平均 FiO2 无差异。
在本研究中，与白天相比，夜间频繁出现 HE 的情况较少。这可能是由于夜间的处理和感官刺激较少。夜间 SpO2 升高的时间增加可能是由于对高 SpO2 的耐受性增加，FiO2 的主动下调减少。
