Can tissue oxygenation index (TOI) and cotside neurophysiological variables predict outcome in depressed/asphyxiated newborn infants?

Background: Diagnostic tools of birth asphyxia provide only an uncertain prediction of neurological outcome.
Aims: To assess whether TOI and DeltaCBV, combined with a set of biochemical and neurophysiological variables, have any diagnostic and prognostic value in birth depression or asphyxia.
Study Design: Case control study at the nursery and NICU of the Padova University Children's Hospital.
Subjects: 22 term neonates with an Apgar score < or = 6 at 5', a 1-h umbilical artery pH value < or = 7.25 with an increased base deficit and a gestational age > or = 36 weeks; 15 healthy term infants with an Apgar score > or = 9 at 5'.
Outcome Measures: Troponin I and NIRS measurements (TOI and DeltaCBV) were assessed in both groups. Blood gases, neurological evaluation, US, NIRS, EEG and SEP were evaluated in the infants with depression or asphyxia.
Results: Troponin I was higher in the study group than in controls (p=0.04), showing a correlation with base excess values. In the depressed/asphyxiated neonates with an abnormal outcome at 1 year, TOI rose to 80.1% vs 66.4% in controls (p=0.04) and 74.7% in infants with a normal 1-year outcome. A multiple regression model showed a significant multiple correlation coefficient, R=0.79, p<0.001, where the predictive variables significantly associated with outcome were SEP and BE.
Conclusions: Troponin I is a useful short-term index of birth asphyxia or perinatal depression. An increased TOI suggests a risk of abnormal neurological outcome at 1 year. Among the cotside variables, BE and evoked potential abnormalities were the best predictors of abnormal outcome in this study.