Background Hypoxic Ischaemic Encephalopathy (HIE) remains a significant cause of neonatal death and long term disability. Heart rate variability (HRV) may help identify the presence and severity of encephalopathy. Our aim was to analyse HRV features in full-term neonates with HIE and assess its ability to grade severity of HIE and predict neurodevelopmental outcome at 2-years of age.
Methods This was a retrospective study of healthy full-term neonates and full-term neonates with HIE. All neonates had multichannel EEG and ECG monitoring from as soon as possible after birth. EEGs were graded at 12, 24, and 48 h (mild, moderate, severe) and 1 h epochs of EEG and ECG data were extracted. Features of HRV were calculated from ECG recordings in each epoch. A comparison of HRV features between HIE and healthy groups and within HIE groups (mild/moderate/severe) was performed. The ability of HRV features to predict neurodevelopmental outcome at 2-years of age was also assessed.
Results 44 neonates with HIE and 17 healthy controls were included. Measures of HRV were significantly negatively correlated with EEG grade of HIE severity. HRV was significantly reduced between mild and moderate HIE groups. EEG grade of HIE measured at 12, 24, and 24 h after birth has a strong positive predictive value and reduced HRV at 24 and 48 h has a strong negative predictive value for 2 year neurodevelopmental outcome.
Conclusion HRV features significantly correlate with the grade of HIE severity and may be useful for the prediction of long term outcome.