Can asphyxiated infants at risk for neonatal seizures be rapidly identified by current high-risk markers?

OBJECTIVE

Markers currently used to identify infants at highest risk for perinatal hypoxic-ischemic cerebral injury are insensitive in predicting the subsequent occurrence of neonatal seizures and/or neurodevelopmental sequelae, ie, cerebral palsy. To facilitate therapeutic strategies, early identification of the infant at highest risk for developing seizures secondary to hypoxia ischemia or asphyxia is critical, particularly if novel but potentially toxic therapies currently under experimental investigation become available for clinical use.

METHODS

Ninety-six inborn term infants considered at high risk for having neonatal seizures secondary to hypoxia ischemia or asphyxia and admitted to the neonatal intensive care unit directly after labor and delivery were prospectively evaluated. Markers of high risk included the presence of moderate to thick meconium-stained amniotic fluid (MSAF), fetal heart rate (FHRT) abnormalities abruptio placentae, intubation and positive pressure ventilation in the delivery room (DR), chest compressions and epinephrine administration as part of resuscitation, a 5-minute Apgar score of 5 or less, umbilical cord arterial pH of 7.00 or less, and/or a base deficit of -14 mEq/L or more negative.

RESULTS

Seizures developed in 5 (5.2%) of the 96 infants. High-risk markers included FHRT abnormalities only (n=36), FHRT abnormalities and MSAF (n=20), MSAF only (n=23), abruptio placentae (n=6), intubation in the DR (n=44), intubation in the neonatal intensive care unit (n=22), chest compressions (n=2), 5-minute Apgar scores of 5 or less (n=21), umbilical cord arterial pH of 7.00 or less (n=21), and base deficits of -14 mEq/L or more negative (n=19). By univariate analysis, significant relationships with seizures were found with Apgar scores, the need for intubation in the DR, umbilical cord arterial pH, and base deficit. Combinations of the identified risk markers showed a strong relationship with seizures with the following odds rations (ORs), 95% confidence limits, sensitivity, specificity, and positive predictive values (PPVs): (1) low cord pH and intubation, OR, 163 (confidence limits, 7.9 and 3343.7); sensitivity, 100%; specificity 94%; and PPV, 50%; (2) low cord pH and low 5-minute Apgar score, OR, 39 (confidence limits, 3.9 and 392.5); sensitivity, 80%; specificity, 91%; and PPV, 33.3%; and (3) low pH, intubation, and low 5-minute Apgar score, OR, 340 (confidence limits, 17.8 and 6480.6); sensitivity, 80%; specificity, 98.8%; and PPV, 80%.

CONCLUSIONS

A combination of high-risk postnatal markers, specifically, a low 5-minute Apgar score and intubation in the DR in association with severe fetal acidemia, facilitates the identification within the first hour of life of term infants at highest risk for developing seizures secondary to perinatal asphyxia.