Agreement between capillary and arterial lactate in the newborn

Arterial blood lactate is a reliable indicator of tissue oxygen debt and is of value in expressing the degree and prognosis of circulatory failure as a result of various diseases. Therefore, the practical issue of whether capillary lactate measurements might be of equal value was investigated in newborns. In total, 193 simultaneous measurements of capillary and arterial blood lactate concentrations were performed in 25 newborn babies with an indwelling umbilical arterial catheter. A strong linear correlation was found between capillary and arterial lactate concentration (Lcap = 1.02 Lart + 0.04; r = 0.98; p < 0.001). The mean difference was -0.08 mmol/l and the limits of agreement (+/- 2 SD) were +/- 0.69 mmol/l (-0.77 to 0.61 mmol/l). Conclusion: Our data show that capillary blood lactate measurements in newborn babies yield lactate concentrations equivalent to arterial measurements over a large concentration range.