The umbilical cord acid-base balance has been used as a measure of intrapartum asphyxia. Van den Berg and associates conducted a retrospective study to evaluate the relationship between an umbilical artery pH of less than 7.00 and neonatal morbidity and mortality.
Eighty-four neonates with an umbilical artery pH of less than 7.00 were compared with 84 neonates with an umbilical artery pH of greater than 7.24. Neonatal morbidity (defined as poor condition after delivery or neurologic, pulmonary, gastrointestinal or cardiovascular complications) and neonatal admissions to the intensive care unit were significantly higher in the acidotic group than in the nonacidotic group, with the exception of renal complications. Two neonates in the acidotic group died. However, 23 acidotic neonates with a pH between 6.80 and 7.00 did not show any signs of neonatal morbidity.
A total of 87.5 percent of the acidotic neonates had mixed acidosis. All neurologic complications were seen in the group with mixed acidosis; no neurologic complications occurred in the group with metabolic acidosis. Almost all neurologic complications occurred in acidotic neonates with a base deficit of 15 mmol per L or greater. All term neonates except one with neurologic dysfunction had an umbilical artery pH of 6.90 or less. Neurologic dysfunction was present in all but one of the preterm infants with an umbilical artery pH between 6.90 and 7.00. Of the 24 neonates in the acidotic group with a one-minute Apgar score of 3 or less, 15 had neurologic complications. A five-minute Apgar score of less than 7 was found in 26 infants, and 13 of these infants had neurologic complications. If the umbilical artery pH was below 6.80, neonates were born severely depressed. With a pH above this value, no relationship was seen between umbilical artery pH and the one- or five-minute Apgar score. None of the nonacidotic infants had a one-minute Apgar score of 3 or less.
Study results indicated that 27 percent of neonates born with a pH between 6.80 and 7.00 had no neonatal complications. This finding suggests that neonatal morbidity may not only depend on the duration and degree of hypoxia, but also on the adequacy of adaptive responses such as redistribution of blood flow. The predictive value of a one-minute Apgar score of 3 or less and a five-minute Apgar score of less than 7 in the acidotic group was high for neurologic dysfunction. However, using only low Apgar scores to indicate the need for determination of acid-base status would overestimate the role of acidemia as a causative factor for neonatal morbidity.
The authors conclude that severe intrapartum asphyxia as quantified by an umbilical artery pH of less than 7.00 poses a threat for neonatal morbidity.
Van den Berg PP, et al. Neonatal complications in newborns with an umbilical artery pH [is less than] 7.00. Am J Obstet Gynecol 1996;175:1152-7.
COPYRIGHT 1997 American Academy of Family Physicians
COPYRIGHT 2004 Gale Group
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Aagenaes syndrome