Abstract
Objective:
Lactate Pro™ (LP1) is the only lactate meter evaluated for fetal scalp blood sampling (FBS) in intrapartum use. The reference values for this meter are: normal value <4.2 mmol/L, preacidemia 4.2–4.8 mmol/L, and acidemia >4.8 mmol/L. The production of this meter has been discontinued. An updated version, Lactate Pro 2TM (LP2), has been launched and is shown to be differently calibrated. The aims of the study were to retrieve a conversion equation to convert lactate values in FBS measured with LP2 to an estimated value if using LP1 and to define reference values for clinical management when using LP2.
Study design:
A cross-sectional study was conducted at a university hospital in Sweden. A total of 113 laboring women with fetal heart rate abnormalities on cardiotocography (CTG) had FBS carried out. Lactate concentration was measured bedside with both LP1 and LP2 from the same blood sample capillary. A linear regression model was constructed to retrieve a conversion equation to convert LP2 values to LP1 values.
Results:
LP2 measured higher values than LP1 in all analyses. We found that 4.2 mmol/L with LP1 corresponded to 6.4 mmol/L with LP2. Likewise, 4.8 mmol/L with LP1 corresponded to 7.3 mmol/L with LP2. The correlation between the analyses was excellent (Spearman’s rank correlation, r=0.97).
Conclusion:
We recommend the following guidelines when interpreting lactate concentration in FBS with LP2: <6.4 mmol/L to be interpreted as normal, 6.4–7.3 mmol/L as preacidemia indicating a follow-up FBS within 20–30 min, and >7.3 mmol/L as acidemia indicating intervention.
Acknowledgments:
We want to express our sincere gratitude to Susanne Falck, RNM, who coordinated fetal scalp blood samplings and collected data. We also want to express gratitude to Sandra Eloranta at Scandinavian Development Services who contributed with excellent statistical analyses.
Disclosure of interests:Medexa AB has provided the LP2 devices and the lactate test strips used in the study but has had no influence on the design of the study, interpretation of data or this publication. None of the researchers have any financial interests.
Details of ethics approval:The study was approved by the Regional Ethics Committee of Karolinska Institutet, Stockholm, Sweden on the 23th of April 2012 with reference number 2012/680-32.
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The authors stated that there are no conflicts of interest regarding the publication of this article.
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