Prognostic value of lactate measurement in very-low-birth-weight infants

For a number of years point-of-care blood lactate measurement has been used to predict outcome for patients suffering a range of critical illnesses. Now a recently published study suggests that this predictive value of lactate measurement can also be usefully applied to very-low-birth-weight (VLBW) neonates born prematurely. 

In short, this study has demonstrated that increased blood lactate (hyperlactatemia) during the first hours of life is associated with poor prognosis for survival among these highly vulnerable babies. The study, which was conducted at Liverpool Women’s Hospital in the UK, focused on all 408 premature babies with VLBW (defined as <1500 g) born at the hospital over a 3-year period. 

Birth weight among this cohort ranged from 370 to 1500 g and gestational age from 23 to 37 weeks. Of the 408 infants, 381 had at least one blood lactate measurement recorded during the first 12 hours of life. All lactate measurements were made using a point-of-care blood gas analyzer sited in the neonatal care unit. 

Forty-seven (47) babies did not survive; median age at death was 3 days, range 1-210 days. Highest blood lactate during the first 12 hours of life was significantly higher among those who died (median 10.2 mmol/L, range 3.37-26) compared with those who survived (median 3.84 mmol/L, range 1.05-20.7). 

The most informative cut-off lactate value for predicting survival or death was 6.9 mmol/L; this had a sensitivity of 77 % and a specificity of 78 %. The authors of this study devised a severity scoring system based on three parameters that were each shown to be powerful independent risk factors for death: highest lactate during the first 12 hours of life; gestational age; and presence of life-threatening malformation. 

They demonstrated that this new simple severity scoring system had equal predictive ability as that of the existing more complex six-parameter scoring system called CRIB currently used in UK neonatal units. The six parameters used for the CRIB score do not include blood lactate value.