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Abstract
Aims To investigate the correlation between the clearance of blood lactate level over the first 96 h of life and neurological outcome in neonates undergoing whole body cooling for hypoxic ischaemic encephalopathy (HIE.)
Methods All neonates undergoing whole body cooling for HIE at a tertiary neonatal centre between 1st January 2007 and 31st December 2010 were identified and a retrospective case note review undertaken. Using documented findings on clinical examination, supplemented with information from letters of latest follow-up clinics, infants were grouped dependent on outcomes of death and normal or abnormal neurology at follow up. Blood lactate measurements recorded at 6, 12, 18, 24, 48, 72 and 96 h (+/- 3 h) were collected and subsequently compared across the three outcome groups. Statistical analysis of data used Mann Whitney-U and Kruskal-Wallis tests and data is provided as median (+/- interquartile range.)
Results 61 infants met the study criteria, with birth weight of 3.31 kg (2.77–3.55), gestation 39 (38–40) weeks, ten minute Apgar score of 5 (2–6), base deficit 18.7 (14.5 to 25.4) and arterial cord pH 6.95 (6.82- 7.08). 100% of the infants were graded moderate/severe HIE. 13 infants died, 14 had abnormal and 34 normal neurological examination at latest follow up. Statistical analysis demonstrated significantly lower blood lactate levels at 6, 12, 18, 24, 48 and 72 h after birth in those with normal neurological follow up compared to those who died. Similarly there was significantly higher lactate levels at 72 h in infants of the abnormal neurological group compared to those of the normal group.
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Conlusions Our study showed that blood lactate measurements in the first 72 h of life show significant statistical differences in neonatal outcome in terms of death, normal or abnormal examination. Blood lactate level is a quick, widely accessible test, and could be used in conjunction with other modalities to help aid prognostication in infants suffering with HIE, allowing more accurate parental counselling and appropriate future care of the infant. We aim to collect further data to develop practical value ranges applicable to this clinical practice.
Table of median lactate levels amongst the three outcome groups at various time intervals with in the first 72 hours of life.
Trends in lactate clearance through the first 72 hours amongst the three outcome groups.