Comparison of two point-of-care testing (POCT) devices for fetal lactate during labor

Abstract

Background: Point-of-care testing (POCT) of fetal scalp blood lactate is used as an alternative for pH analysis. Lactate measurements have not been standardized and values vary with each device used. The aim of this study was to evaluate the performance of two POCT lactate meters for intrapartum use.

Methods: Analytical performance of StatStrip Lactate (Nova Biomedical) and Lactate Pro (Arkray) was evaluated using CLSI EP10. Both POCT meters were compared with our lactate reference method (RapidLab 860; Siemens Healthcare Diagnostics) using fetal scalp and neonatal cord blood. Deming regression analysis was performed.

Results: StatStrip Lactate coefficients of variation (CVs) were 5.1%, 5.0% and 2.6% at 0.9, 7.5 and 14.1 mmol/L lactate, respectively. CVs for Lactate Pro were 10.7%, 5.2% and 5.7% at 1.7, 4.1 and 6.4 mmol/L lactate, respectively. Consecutive lactate measurements in 37 fetal scalp and 122 cord blood samples revealed different test characteristics for the two POCT devices. In fetal scalp blood: StatStrip Lactate=1.13*RapidLab–0.39 (R²=0.907) and Lactate Pro=0.95*RapidLab–0.03 (R²=0.823). In cord artery blood: StatStrip Lactate=1.08*RapidLab–0.09 (R²=0.810) and Lactate Pro=0.72*RapidLab+0.59 (R²=0.807).

Conclusions: Overall performance of both Lactate Pro and StatStrip Lactate was good, with StatStrip Lactate having smallest CVs and closest correlation to our reference method. Both StatStrip Lactate and Lactate Pro can be used as a lactate POCT device for obstetric use.