Evaluation of agreement between point-of-care and blood gas analyzers for lactate measurement in critically ill dogs

This study aimed to evaluate the analytical agreement between a handheld point-of-care (POC) lactate meter (StatStrip Xpress®2 Lac/Hb/Hct, Nova Biomedical) and a standard blood gas analyzer (Stat Profile Prime Plus® VET, Nova Biomedical) for measuring plasma lactate concentrations in critically ill dogs. Fifty-seven client-owned dogs were admitted to the Emergency Unit and Critical Care Unit (CCU) of the Small Animal Hospital, Chulalongkorn University, enrolled. Blood samples were analyzed using both a handheld POC meter and a blood gas analyzer. To evaluate analytical agreement across a wide concentration range, data were categorized into low (1–4 mmol/L; n = 17), moderate (4–10 mmol/L; n = 28), and high (10–20 mmol/L; n = 12) lactate groups. Spearman’s correlation, Passing-Bablok regression, and Bland-Altman analysis were performed to assess the agreement between the two devices. One-way ANOVA was used to analyze differences among the three groups. A strong positive correlation was observed between the two devices (r = 0.99). Passing–Bablok regression demonstrated acceptable agreement, with slopes of 1.02, 0.94, 1.01, and 1.38 for the overall dataset, low, moderate, and high lactate groups, respectively. Bland–Altman analysis showed mean biases of 0.07, 0.02, 0.26, and –0.57 mmol/L for the overall dataset, low-, moderate-, and high-lactate groups, respectively, indicating that the mean differences between the instruments were within acceptable analytical limits across most lactate ranges. In contrast, one-way ANOVA revealed a significant difference between the highlactate group and the others. In conclusion, the handheld POC lactate meter demonstrated a high degree of agreement with the standard blood gas analyzer, particularly in the low- and moderate-lactate groups.