Asphyxial complications in the term newborn with severe umbilical acidemia

Our purpose was to determine the relationship of umbilical acid-base status and Apgar score to neonatal asphyxial sequelae in infants with severe acidemia (pH < 7.00).

The obstetric and neonatal course of 129 term, nonanomalous singleton infants with umbilical pH < 7.00 was reviewed.

There were three stillbirths (failed resuscitation). Seventy-two of 126 (57%) were admitted to the neonatal intensive care unit. Thirty-eight percent had pulmonary dysfunction, 26% renal dysfunction, 31% cardiac dysfunction, and 31% hypoxic ischemic encephalopathy (seizures and hypotonia, n = 29; seizures only, n = 3; hypotonia only, n = 10). There were five neonatal deaths. In 109 cases umbilical arterial values were available, and among these infants there was a significant increase in the incidence of seizures with declining pH from 9% (5/57), with a pH of 6.90 to 6.99, to 80% (8/10), with a pH of 6.61 to 6.70. Respiratory acidemia (PCO2 > 65, base deficit < 10) was identified in 28 of 109 (26%), all but six occurring in the pH range above 6.90. Compared with infants with comparable umbilical artery pH, infants with respiratory acidemia did not differ significantly with respect to asphyxial end-organ injury in general (8/35 vs 6/22), but there was a trend toward a lower incidence of hypoxic ischemic encephalopathy (6/35 vs 1/22, p = 0.06). All infants with definite abnormal outcome (five neonatal deaths and 10 severe neurologic deficit) had seizures, hypotonia, and at least one other organ system dysfunction. Twenty-four of 29 infants (83%) who developed seizures had a 5-minute Apgar score < 7, but only 12 of 29 (41%) had a 5-minute Apgar score of < or = 3. Two infants with Apgar scores of 6 and 7 at 5 minutes and no evidence of nonasphyxial comorbidity subsequently manifested profound neurologic deficit.

Infants with severe umbilical acidemia can be separated with regard to risk of hypoxic ischemic encephalopathy and abnormal neurologic outcome by consideration of the severity and composition of the acidemia and evidence of other end-organ dysfunction. Even in this pH range the Apgar score is not highly predictive of asphyxial complications.