Correlation of Arterial Lactate and pH With the Immediate Outcome of Term Asphyxiated Neonates

Perinatal asphyxia is a significant cause of neonatal morbidity and mortality. Early identification of neonates at risk for adverse outcomes is crucial for timely intervention. This study aimed to evaluate the prognostic value of arterial lactate and pH levels in predicting immediate clinical outcomes in term asphyxiated neonates. Additionally, the study explored the potential association between elevated lactate levels and hearing impairment.

This observational cross-sectional study was conducted at a tertiary care center in Bhopal, India. A total of 100 term neonates with birth asphyxia were enrolled. Neonates admitted within six hours of birth had their arterial lactate and pH levels measured within the first hour of neonatal intensive care unit (NICU) admission. Survival rates, neurological outcomes at discharge, and hearing assessment of asphyxiated neonates through otoacoustic emissions (OAE) were the primary and secondary objectives. Statistical analysis involved Pearson's correlation and receiver operating characteristic (ROC) curves to determine optimal pH and lactate thresholds for predicting adverse outcomes.

A lactate threshold of 6.2 mmol/L was predictive of neurological abnormalities (area under the curve (AUC) 0.85, sensitivity 76%, specificity 79%), while a threshold of 10 mmol/L was associated with increased mortality (AUC 0.77, sensitivity 59%, specificity 88%). pH levels <7.2 were linked to a higher risk of death (AUC 0.79, sensitivity 71%, specificity 77%). pH levels below 7.3 were associated with a greater risk of neurologically abnormal neonates (AUC 0.78, sensitivity 83%, specificity 62%). Neonates who failed OAE screening had significantly higher lactate levels compared to those who passed, suggesting an association between higher lactate values and hearing impairment in asphyxiated neonates. The median (IQR) lactate levels for the B/L Pass and B/L Refer groups were 4.3 (3.1, 6.8) and 7.4 (6.3, 10.3), respectively.

Arterial lactate and pH are valuable biomarkers for the early prediction of neurological abnormalities, mortality, and hearing impairment in term asphyxiated neonates. Integrating these measurements into neonatal care protocols may enhance risk stratification and guide early interventions.