Prospective validation of a scoring system for predicting neonatal morbidity after acute perinatal asphyxia

Abstract

Objective: To prospectively validate a previously reported scoring system for identifying the near-term infant at risk for the multiple organ system sequelae of acute perinatal asphyxia.

Study design: Prospective observational study.

Setting: Three Denver teaching hospitals, each providing comprehensive obstetric care.

Subjects: Newborn infants of 36 weeks or more gestation.

Intervention: None.

Statistical analysis: Chi-squared analysis with Fisher's exact test.

Outcome: Scores consisting of graded abnormalities in fetal heart rate monitoring, umbilical arterial base deficit, and 5-minute Apgar score were calculated by the research nurse after admission of the infant to the nursery (range of possible scores, 0 to 9). A second nurse, blinded to these data, prospectively followed the newborn's hospital course for multiple organ system morbidity.

Results: Three thousand two hundred thirty-eight newborns were studied; 366 required neonatal intensive care unit admission. Eleven newborns had a score > or = 6 (mean umbilical artery pH = 6.98, base deficit = 17.1 mEq/L). Morbidities in these 11 newborns included seizures (2), hypoxic-ischemic encephalopathy (5), respiratory distress (9), hypotension (7), renal dysfunction (9), hypoglycemia/hypocalcemia (4), and thrombocytopenia or disseminated intravascular coagulopathy (3). The odds ratio (OR) and 95% confidence interval (CI) for newborns admitted to the neonatal intensive care unit with a score > or = 6 for having multiple organ system morbidity, defined as three or more affected organ systems, was 38.5 (95% CI, 9.2 to 127.8). The scoring system showed a stronger relationship with multiple organ system morbidity than did isolated individual indicators commonly used to identify asphyxia calculated on the same subjects: for those with pH < 7.00, OR 24 (95% CI, 6.4 to 94.1); base deficit > or = 10 mEq/L, OR 4.5 (95% CI, 1.9 to 10.3), and 5-minute Apgar score < or = 3, OR 7.4 (95% CI, 1.3 to 38.1).

Conclusion: This scoring system, encompassing both immediate intrapartum and postpartum measures and acid-base status proximate to the time of delivery, is useful for rapidly identifying the term and near-term newborn at risk for multiple organ system morbidity after acute perinatal asphyxia.