Reference values for Lactate Pro 2™ in fetal blood sampling during labor: a cross-sectional study

Area of Science:

• Obstetrics and Gynecology
• Neonatal Medicine
• Clinical Chemistry

Background:

• The Lactate Pro™ (LP1) was the sole lactate meter validated for fetal scalp blood sampling (FBS) during labor.
• LP1 reference values: normal <4.2, preacidemia 4.2-4.8, acidemia >4.8 mmol/L.
• LP1 production ceased; the updated Lactate Pro 2™ (LP2) is differently calibrated.

Purpose of the Study:

• To develop a conversion equation for estimating LP1 lactate values from LP2 measurements in FBS.
• To establish new reference values for clinical interpretation using the LP2 meter during labor.

Main Methods:

• A cross-sectional study involved 113 laboring women with fetal heart rate abnormalities.
• Fetal scalp blood (FBS) lactate was measured concurrently using both LP1 and LP2 devices.
• Linear regression analysis was employed to derive the conversion equation.

Main Results:

• LP2 consistently yielded higher lactate concentrations than LP1.
• LP1's 4.2 mmol/L normal threshold corresponded to 6.4 mmol/L on LP2.
• LP1's 4.8 mmol/L acidemia threshold corresponded to 7.3 mmol/L on LP2; correlation was excellent (r=0.97).

Conclusions:

• Recommended LP2 interpretation guidelines: <6.4 mmol/L (normal), 6.4-7.3 mmol/L (preacidemia, requires follow-up FBS).
• >7.3 mmol/L indicates acidemia requiring intervention.
• These guidelines facilitate accurate clinical management with the new LP2 lactate meter.