Umbilical artery carbon dioxide decreases the risk for hypoxic-ischaemic encephalopathy.

Abstract

An accurate biomarker for metabolic acidosis at birth is needed. Our aims were to investigate the link between umbilical artery pCO2 and the risk for hypoxic-ischaemic encephalopathy (HIE) and to compare false-negative screen results in newborn infants with HIE using three umbilical artery blood gas biomarkers. From a cohort of newborn infants ≥35weeks born in Ottawa, Canada, between January 2007 and December 2016, we highlighted those with HIE or who died. We compared the umbilical artery pCO2 for matched pH >mean versus matched pH ≤mean. We compared false-negative rates for three umbilical artery biomarkers-pH <7.0, base deficit ≥16mmol/L and neonatal eucapnic pH ≤7.14. This study included 51286 newborn infants, 51% male and a mean gestational age of 38.9±1.5weeks. The rate for HIE or death with umbilical artery pCO2 for matched pH >mean was 22%, compared to 78% for matched pH ≤mean. In 60 HIE or deaths, the false-negative rate for umbilical artery neonatal eucapnic pH ≤7.14 was 8%; compared to 31% for pH <7.00 and 36% for base deficit ≥16mmol/L. The rate of HIE or death is lower in newborn infants with higher pCO2 . Using neonatal eucapnic pH decreases the risk of missing newborn infants with HIE.