Arteriovenous differences in cord blood gas analysis and the prediction of adverse neonatal outcome.

Abstract

The aim of this paper was to determine whether arteriovenous differences of pH and pCO2 are useful predictors of adverse neonatal outcome in acidemic neonates. An established database of 8759 term, singleton, non-anomalous neonates with validated cord gases and outcomes [Encephalopathy (Grade 2/3), Apgar <7 at five minutes and composite neonatal outcomes of neurological and systemic involvement] was used. Analysis was of the cohort of the 520 acidemic (arterial pH <7.10) neonates. Chi-square tests with odds ratio (OR), 95% CI were calculated for dichotomous cut-offs of differences; hierarchical logistic regression was used to examine the predictive performance over and above arterial pH. Arteriovenous hydrogen ion concentration ([H+ ion]) differences do not predict neonatal outcomes except low Apgar scores, and large pCO2 differences are associated with worse neonatal outcomes. Nevertheless, neonates with large arteriovenous [H+ ion] and pCO2 differences have lower arterial pH values. Hierarchical regression demonstrates that arteriovenous pCO2 differences do not add predictive value beyond arterial pH and arteriovenous [H+ ion] adds only to the prediction of low Apgar scores. Arteriovenous differences of [H+ ion] and pCO2 are not useful independent predictors of adverse neonatal outcomes in acidemic neonates.