Racinet C, Richalet G, Corne C, Faure P, Peresse J-F, Leverve X
Université J-Fourier, Grenoble, France.
Gynecol Obstet Fertil. 2013 Sep;41(9):485-92. doi: 10.1016/j.gyobfe.2013.07.020. Epub 2013 Aug 27.
The identification of a metabolic acidosis is a key criterion for establishing a causal relationship between fetal perpartum asphyxia and neonatal encephalopathy and/or cerebral palsy. The diagnostic criteria currently used (pH and base deficit or lactatemia) are imprecise and non-specific.
The study aimed to determine among a low-risk cohort of infants born at term (n = 867), the best diagnostic tool of metabolic acidosis in the cordonal from the following parameters: pH, blood gases and lactate values at birth.
The data were obtained from arterial blood of the umbilical cord by a blood gas analyser. The parameter best predicting metabolic analysis was estimated from the partial correlations established between the most relevant parameters.
The results showed a slight change in all parameters compared to adult values: acidemia (pH: 7.28 ± 0.01), hypercapnia (56.5 ± 1.59 mmHg) and hyperlactatemia (3.4 ± 0.05 mmol/L). From partial correlation analysis, pCO(2) emerged to be the main contributor of acidemia, while lactatemia was shown to be non-specific for metabolic acidosis. Seven cases (0.81 %) showed a pH less than 7.00 with marked hypercapnia. The correction of this respiratory component by EISENBERG's method led to the eucapnic pH, classifying six out of seven cases as exclusive respiratory acidosis.
It has been demonstrated that the criteria from ACOG-AAP for defining a metabolic acidosis are incomplete, imprecise and generating errors in excess. The same is true for lactatemia, whose physiological significance has been completely revised, challenging the misconception of lactic acidosis as a specific marker of hypoxia. It appeared that eucapnic pH was the best way for obtaining a reliable diagnosis of metabolic acidosis. We proposed to adopt a simple decision scheme for determining whether a metabolic acidosis has occurred in case of acidemia less than 7.00.
代谢性酸中毒的识别是确定胎儿分娩时窒息与新生儿脑病和/或脑瘫之间因果关系的关键标准。目前使用的诊断标准（pH值、碱缺失或血乳酸水平）不准确且不具特异性。
本研究旨在确定在一个足月出生的低风险婴儿队列（n = 867）中，根据以下参数：出生时的pH值、血气和乳酸值，脐带血中代谢性酸中毒的最佳诊断工具。
数据通过血气分析仪从脐带动脉血中获取。根据最相关参数之间建立的偏相关性来估计最能预测代谢分析的参数。
结果显示与成人值相比，所有参数均有轻微变化：酸血症（pH值：7.28 ± 0.01）、高碳酸血症（56.5 ± 1.59 mmHg）和高乳酸血症（3.4 ± 0.05 mmol/L）。通过偏相关分析，pCO₂ 是酸血症的主要促成因素，而血乳酸水平对代谢性酸中毒不具特异性。7例（0.81%）显示pH值低于7.00且伴有明显的高碳酸血症。用艾森伯格方法校正这种呼吸成分后得出了正常碳酸血症pH值，7例中有6例被归类为单纯性呼吸性酸中毒。
已证明美国妇产科医师学会-美国儿科学会定义代谢性酸中毒的标准不完整、不准确且会产生过多误差。血乳酸水平也是如此，其生理意义已被完全重新审视，对将乳酸酸中毒视为缺氧特异性标志物的错误观念提出了挑战。看来正常碳酸血症pH值是获得代谢性酸中毒可靠诊断的最佳方法。我们建议采用一个简单的决策方案，以确定在酸血症低于7.00时是否发生了代谢性酸中毒。
