Umbilical artery gas results help obstetricians assess fetal well-being during labor and guide screening decisions on eligibility for therapeutic hypothermia (ie, whole-body or head cooling). The accuracy of results, especially for the base deficit on arterial cord gas analysis, in predicting brain injury is questioned. A novel biomarker specifically calculated for fetal acid-base physiology and response to asphyxia—neonatal eucapnic pH as a marker of neonatal metabolic acidosis—has the potential to be an accurate predictor of hypoxic-ischemic encephalopathy. We aimed to compare false-negative rates of hypoxic-ischemic encephalopathy for umbilical artery pH, base deficit, and neonatal eucapnic pH in assessing fetal acid-base balance as a marker of fetal well-being and predicting acute brain injury. This is a retrospective single-center cohort study of newborns ≥ 35 weeks of gestation diagnosed with hypoxic-ischemic encephalopathy. We compared false-negative rates for any grade of hypoxic-ischemic encephalopathy using unilateral paired chi-square statistical analysis based on cutoff values for umbilical artery pH ≤7.00, base deficit ≥16 mmol/L, base deficit ≥12 mmol/L and neonatal eucapnic pH ≤7.14. We performed an analysis of variance between umbilical artery pH, base deficit, and neonatal eucapnic pH for each hypoxic-ischemic encephalopathy grade. We included 113 newborns. False-negative rate for hypoxic-ischemic encephalopathy was significantly higher for base deficit <16 mmol/L (n=78/113; 69.0%) than <12 mmol/L (n=46/113; 40.7%), pH >7.00 (n=41/113; 36.3%), or neonatal eucpanic pH >7.14 (n=35/113; 31.0%) (<.0001). All true-positive cases were identified using only umbilical artery pH and neonatal eucapnic pH. Base deficit ≥16 or ≥12 mmol/L did not add any value in identifying newborns with hypoxic-ischemic encephalopathy when using umbilical artery pH and neonatal eucapnic pH. No association emerged between any marker and hypoxic-ischemic encephalopathy severity grading. Our findings support the accuracy of neonatal eucapnic pH to assess fetal well-being during labor and to improve predictive performance for acute brain injury. Neonatal eucpanic pH, in addition to umbilical artery pH, may be a viable alternative in identifying newborns at risk for hypoxic-ischemic encephalopathy.

中文翻译：

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脐动脉 eucapnic pH 值评估胎儿健康

脐动脉气体结果有助于产科医生评估分娩期间胎儿的健康状况，并指导有关治疗性低温（即全身或头部冷却）资格的筛查决策。预测脑损伤的结果的准确性，特别是动脉脊髓气体分析的碱基缺失，受到质疑。一种专门针对胎儿酸碱生理学和窒息反应计算的新型生物标志物——新生儿无二氧化碳 pH 值作为新生儿代谢性酸中毒的标志物——有可能成为缺氧缺血性脑病的准确预测因子。我们的目的是比较缺氧缺血性脑病的脐动脉 pH 值、碱缺乏和新生儿常碳酸 pH 值的假阴性率，以评估胎儿酸碱平衡作为胎儿健康的标志并预测急性脑损伤。这是一项针对妊娠 ≥ 35 周被诊断患有缺氧缺血性脑病的新生儿的回顾性单中心队列研究。我们使用单侧配对卡方统计分析比较了任何级别的缺氧缺血性脑病的假阴性率，该统计分析基于脐动脉 pH ≤ 7.00、碱缺乏 ≥ 16 mmol/L、碱缺乏 ≥ 12 mmol/L 和新生儿的截止值真二氧化碳pH值≤7.14。我们对每种缺氧缺血性脑病级别的脐动脉 pH 值、碱缺乏和新生儿常碳酸 pH 值之间的差异进行了分析。我们纳入了 113 名新生儿。缺氧缺血性脑病的假阴性率在碱缺乏 <16 mmol/L (n=78/113; 69.0%) 时显着高于 <12 mmol/L (n=46/113; 40.7%)，pH >7.00 (n=41/113; 36.3%)，或新生儿纯 pH >7.14 (n=35/113; 31.0%) (<.0001)。所有真阳性病例均仅使用脐动脉 pH 值和新生儿 eucapnic pH 值进行鉴定。当使用脐动脉 pH 值和新生儿常碳酸 pH 值时，碱缺乏 ≥16 或 ≥12 mmol/L 对于识别新生儿缺氧缺血性脑病没有任何价值。任何标记物与缺氧缺血性脑病严重程度分级之间均未出现关联。我们的研究结果支持新生儿纯碳酸 pH 值的准确性，可用于评估分娩期间胎儿的健康状况并提高急性脑损伤的预测性能。除了脐动脉 pH 值之外，新生儿全身 pH 值可能是识别新生儿缺氧缺血性脑病风险的可行替代方案。