Serial measurements of blood lactate and early outcome of neonatal hypoxic ischemic encephalopathy after therapeutic hypothermia

Objective: To assess predictive value of blood lactate measurements in infants during therapeutic hypothermia due to moderate to severe asphyxia in relation to early outcome. Patients and methods: We retrospectively evaluated records of 47 full-term newborns that underwent therapeutic hypothermia after moderate to severe perinatal asphyxia from January 2011 to December 2015. Criteria for whole body cooling were established according to Bristol Cooling Protocol UK, including clinical signs of HIE using Sarnat&Sarnat scale and aEEG. Blood samples were taken from venous catheter in recommended intervals (3, 6, 12, 24, 48, 72 hours). Early outcome is evaluated on the base of survival rate, neurologic status at discharge and presence of post hypoxic lesions confirmed with brain MRI. All investigated infants were categorized into 3 groups 1) Infants with normal brain MRI finding and normal neurologic examination at the discharge; 2) Infants with abnormal brain MRI finding at the discharge (with 2 subgroups depending of neurological status at the discharge); 3) Newborns with lethal outcome. Results: Mean value of blood lactate at admission for all subjects was 11.87 ± 5.41 (3.224.0), without statistical difference between groups. Three hours after beginning of cooling mean value was 8.36 ± 3.70 (2.2-17.0) with statistical difference between all groups of survived infants compared to infants who died. After 6 and 12 hours mean values were 6.311 ± 3.69 and 6.269 ± 3.37 respectively with statistical difference between neurologically asymptomatic infants (including those with MRI finding interpreted as a mild lesion) compared to infants with abnormal neurological examination at the discharge and infants who died. Values of blood lactate after 24h, 48h and 72 h were 4.46 ± 2.00 (1.0–11.7), 3.60 ± 1.36 (1.6–6.9), 3.36 ± 1.93 (1.29.3) respectively. After 24 h we did not find statistical difference between groups. Conclusion: Serial measurements of blood lactate during therapeutic hypothermia in asphyxiated infants are important. Initial value of lactate is not proved to be predictive, but prompt decreasing of lactate values within 24 hours of cooling is associated with better early outcome. *Correspondence to: Suada Heljić, MD, PhD, NICU, Pediatric Clinic, Clinical University Center Sarajevo, Bosnia and Herzegovina, Tel: +387 61 865 285 (M), +38733566439 (W); E-mail: heljicsuada@hotmail.com