Postnatal lactate as an early predictor of short-term outcome after intrapartum asphyxia

Abstract

Objectives: To compare the predictive value of pH, base deficit and lactate for the occurence of moderate-to-severe hypoxic ischaemic encephalopathy (HIE) and systemic complications of asphyxia in term infants with intrapartum asphyxia. Study Design: We retrospectively reviewed the records of 61 full-term neonates (≥37 weeks gestation) suspected of having suffered from a significant degree of intrapartum asphyxia from a period of January 1997 to December 2001. The clinical signs of HIE, if any, were categorized using Sarnat and Sarnat classifications as mild (stage 1), moderate (stage 2) or severe (stage 3). Base deficit, pH and plasma lactate levels were measured from indwelling arterial catheters within 1 hour after birth and thereafter alongwith every blood gas measurement. The results were correlated with the subsequent presence or absence of moderate-to-severe HIE by computing receiver operating characteristics curves. Results: The initial lactate levels were significantly higher (p = 0.001) in neonates with moderate-to-severe HIE (mean ± SD = 11.09 ± 4.6) as compared to those with mild or no HIE (mean ± SD = 7.1 ± 4.7). Also, the lactate levels took longer to normalize in these babies. A plasma lactate concentration >7.5 ± mmol/l was associated with moderate-or-severe HIE with a sensitivity of 94% and specificity of 67%. The sensitivity and negative predictive value of lactate was greater than that of the pH or base deficit. Conclusions: The highest recorded lactate level in the first hour of life and serial measurements of lactate are important predictors of moderate-to-severe HIE.