Perinatal brain damage: predictive value of metabolic acidosis and the Apgar score.

TLDR

The study aimed to evaluate whether birth acidosis, alone or combined with the 5‑minute Apgar score, predicts perinatal brain damage in a cohort of 982 infants. Umbilical cord blood was double‑clamped to obtain arterial acid‑base and lactate measurements in 964 and 931 infants, respectively, with reference ranges established from 127 uncomplicated term infants. Among the infants, low pH occurred in 12 %, high base deficit in 7 %, high lactate in 9 %, and low 5‑minute Apgar in 3 %; at one year, adverse outcomes were rare, and the sensitivity and positive predictive value of low pH were 21 % and 8 %, indicating that metabolic acidosis at birth is a poor predictor of perinatal brain damage.

Abstract

To assess the predictive value for perinatal brain damage of acidosis at birth, alone or in combination with the Apgar score at 5 minutes, a cohort of 982 liveborn infants delivered over two months was studied prospectively. The umbilical cord was double clamped, and arterial acid-base values were successfully determined in 964 infants and lactate concentration in 931. Reference values defining acidosis (mean +/- 2 SD) were obtained from a subset of 127 term infants who had no complications. The incidence of a low pH was 12% (111 out of 964), high base deficit 7% (70 out of 964), high lactate concentration 9% (83 out of 931), and low Apgar score at 5 minutes (less than or equal to 7) 3% (32 out of 982). Twelve of the 111 infants (11%) with acidosis had a low Apgar score, and 12 out of 29 infants (41%) with low Apgar scores had acidosis. At one year of age 35 infants were lost to follow up and 22 had an adverse outcome unrelated to asphyxia; 883 infants showed normal development but the possible sequelae of asphyxia were four deaths, slight abnormalities in 28 infants, and clear abnormalities in 10. The sensitivity and the positive predictive value of low pH for adverse outcome were, respectively, 21 and 8%, of high lactate concentration 12 and 5%, and of low 5 minute Apgar score 12 and 19%. Metabolic acidosis determined in blood from the umbilical artery at birth is a poor predictor of perinatal brain damage.