Accuracy of a hand-held lactate meter in measuring umbilical cord blood lactate at all lactate levels

Objective: Fetal scalp lactate has largely replaced pH analysis to assess intrapartum hypoxia. Many obstetrics units use hand-held lactate meters to measure umbilical blood because of its affordability and ease of use. We sought to investigate the agreement of Lactate Pro with a reference method blood gas analyser and to determine its usefulness with a recommended cutoff value of 4.8 mmol/L. Methods: Prospective study carried out at a tertiary institution where 237 arterial and 233 venous samples from umbilical cords of 16 elective caesarean and 285 emergency deliveries were measured using Lactate Pro and ABL735 Sesries AcidBase analyser. Limits of agreement were analysed using Bland-Altman plots. Results: Lactate Pro differentiated fewer deliveries as “high risk” (≥4.8 mmol/L) and more as “low risk” (<2.2 mmol/L). Limits of agreement for lactate values (as measured by Lactate Pro) were –1.46 0.97 mmol/L for arterial lactate levels <4.8 mmol/L and –3.21 0.88 mmol/L for arterial lactate levels ≥ 4.8 mmol/L. Conclusion: There was a poorer agreement between the two devices at higher lactate values. Lactate Pro underestimates by up to 3.2 mmol/L; a 4.8 mmol/L reading may actually signify a lactate level of 8.0 mmol/L, indicating severe metabolic acidosis. We caution the use of this device in assessing fetal lactate levels.