Relationship between the umbilical cord blood acid-base status and neonatal hypoxic-ischemic encephalopathy

Materials and methods. A retrospective case-control study included 180 women and their newborns. The levels of pH, lactate (Lac), base deficit (BD), partial oxygen pressure (pOJ, and partial carbon dioxide pressure (pCO) in umbilical cord arterial blood were determined using an ABL800 FLEX gas analyzer (Radiometer Medical ApS, Denmark). Results. Neonates with HIE had significantly lower pH [6.966 (0.309) versus 7.269 (0.074), p <0.001] and higher BD and Lac levels than neonates in the control group [18.1 (6.8) versus 7.9 (4.1), p <0.001 and 12.0 (5.1) versus 5.8 (2.7) mmol/L, p <0.001], respectively; pCO2 was significantly higher in newborns with HIE [59.7 (32.3) versus 41.7 (8.8), p=0.049], while pO2 was higherin the control group [28.1 (28.3) versus 21.3 (11.0), p <0.001]. The arterial umbilical cord blood pH was significantly lower, and BD was higher in newborns with grade II-II HIE than in those with grade I HIE [6.861 (0.309) versus 7.033 (0.163), p=0.04 and 21.7 (6.7) versus 16.2 (6.1)], p=0.02. Lac, pO2, and pCO2 levels were not associated with HIE severity. The predictors of moderate and severe HIE of hypoxic origin were pH <7.03 and BD> 19.2. The severity of HIE was associated with the incidence of adverse long-term outcomes. In 10 HIE cases (27.7%), ABB parameters at birth did not confirm the presence of metabolic acidosis. Conclusion. Determination of the pH and BD in umbilical cord arterial blood allows prediction of the development and severity of HIE. The proposed model for predicting moderate and severe HIE has a sensitivity and specificity of 94.7% and 90.9%, respectively. In 27.7% of cases, HIE was diagnosed in neonates with normal pH and BD in umbilical cord arterial blood, suggesting that there are causes of encephalopathy other than intrapartum fetal hypoxia.

hypoxic-ischemic encephalopathy, HIE, umbilical cord arterial blood, pH, lactate, base deficit, fetal hypoxia