Datasheet1_Comparison of oxygen supplementation in very preterm infants: Variations of oxygen saturation features and their application to hypoxemic episode based risk stratification.pdf

BackgroundOxygen supplementation is commonly used to maintain oxygen saturation (SpO2) levels in preterm infants within target ranges to reduce intermittent hypoxemic (IH) events, which are associated with short- and long-term morbidities. There is not much information available about differences in oxygenation patterns in infants undergoing such supplementations nor their relation to observed IH events. This study aimed to describe oxygenation characteristics during two types of supplementation by studying SpO2 signal features and assess their performance in hypoxemia risk screening during NICU monitoring.
Subjects and methodsSpO2 data from 25 infants with gestational age <32 weeks and birthweight <2,000 g who underwent a cross over trial of low-flow nasal cannula (NC) and digitally-set servo-controlled oxygen environment (OE) supplementations was considered in this secondary analysis. Features pertaining to signal distribution, variability and complexity were estimated and analyzed for differences between the supplementations. Univariate and regularized multivariate logistic regression was applied to identify relevant features and develop screening models for infants likely to experience a critically high number of IH per day of observation. Their performance was assessed using area under receiver operating curves (AUROC), accuracy, sensitivity, specificity and F1 scores.
ResultsWhile most SpO2 measures remained comparable during both supplementations, signal irregularity and complexity were elevated while on OE, pointing to more volatility in oxygen saturation during this supplementation mode. In addition, SpO2 variability measures exhibited early prognostic value in discriminating infants at higher risk of critically many IH events. Poincare plot variability at lag 1 had AUROC of 0.82, 0.86, 0.89 compared to 0.63, 0.75, 0.81 for the IH number, a clinical parameter at observation times of 30 min, 1 and 2 h, respectively. Multivariate models with two features exhibited validation AUROC > 0.80, F1 score > 0.60 and specificity >0.85 at observation times ≥ 1 h. Finally, we proposed a framework for risk stratification of infants using a cumulative risk score for continuous monitoring.
ConclusionAnalysis of oxygen saturation signal routinely collected in the NICU, may have extensive applications in inferring subtle changes to cardiorespiratory dynamics under various conditions as well as in informing clinical decisions about infant care.

研究背景
氧疗（oxygen supplementation）常被用于将早产儿的血氧饱和度（oxygen saturation, SpO2）维持在目标范围内，以减少间歇性低氧血症（intermittent hypoxemic, IH）事件的发生——此类事件与早产儿的短期及长期并发症密切相关。目前针对接受此类氧疗的新生儿，其氧合模式的差异以及与观察到的IH事件的关联的相关研究信息仍较为匮乏。本研究旨在通过分析SpO2信号特征，描述两种氧疗方式下的氧合特征，并评估其在新生儿重症监护病房（neonatal intensive care unit, NICU）监测中用于低氧血症风险筛查的性能。

研究对象与方法
本二次分析纳入了25名胎龄＜32周、出生体重＜2000g的早产儿的SpO2数据，这些受试者均接受了低流量鼻导管（low-flow nasal cannula, NC）与数字化伺服控制氧环境（digitally-set servo-controlled oxygen environment, OE）两种氧疗方式的交叉试验。研究人员对与信号分布、变异性及复杂性相关的特征进行了估算与分析，以对比两种氧疗方式间的差异。采用单变量与正则化多变量逻辑回归方法，识别出相关特征，并构建筛查模型，以预测每日观察期间发生大量IH事件的高风险早产儿。通过受试者工作特征曲线下面积（area under receiver operating curves, AUROC）、准确率、灵敏度、特异度及F1分数评估模型性能。

研究结果
尽管两种氧疗方式下多数SpO2指标水平相当，但采用OE氧疗时，信号不规则性与复杂性均有所升高，提示该氧疗模式下血氧饱和度的波动程度更高。此外，SpO2变异性指标在区分每日发生大量IH事件的高风险早产儿方面，展现出早期预后价值。延迟1步的庞加莱图（Poincare plot）变异性指标的AUROC分别为0.82、0.86、0.89；而作为临床参数的每日IH事件数在观察时长为30分钟、1小时及2小时时的AUROC分别为0.63、0.75、0.81。包含两项特征的多变量模型在观察时长≥1小时时，验证集AUROC＞0.80、F1分数＞0.60且特异度＞0.85。最后，本研究提出了一种基于累积风险评分的早产儿风险分层框架，用于持续监测。

研究结论
对NICU中常规采集的血氧饱和度信号进行分析，有望在多种临床场景下推断心肺动力学的细微变化，同时为新生儿护理的临床决策提供参考依据。