Electrolyte measurement in goats: Comparison of 2 blood gas analyzers and evaluation of the preanalytical blood sample preparation on measurement results.

OBJECTIVE

1. To evaluate agreement for electrolyte measurements in goats between a handheld point-of-care analyzer (Abaxis VetScan i-STAT 1) (POC) and a benchtop blood gas analyzer (Opti CCA-TS2) (VBG) and 2) to evaluate effect of sample type on electrolytes values reported by both analyzers.

MATERIAL AND METHODS

In 21 hospitalized caprine patients and 9 healthy research goats, blood samples were collected into heparin-containing tubes (Sodium Heparin 33 IU/2 ml) (TUBE) and a heparinized syringe (Sodium Heparin 430 IU/ml) (SYRINGE). Samples were analyzed using a POC analyzer as well as VBG. Analyzer results were compared using Bland-Altman analysis and Pearson correlation. Comparison between samples was performed using repeated measures ANOVA.

RESULTS

Between analyzers, TUBE yielded a bias (95 % limits of agreement) of 0.07 mmol/l (-4.37 to 4.52) for sodium, while SYRINGE yielded a bias of -6.13 mmol/l (-11.04 to -1.22). Comparison of potassium yielded a bias of 0.09 mmol/l (-0.5 to 0.67) and 0.08 mmol/l (-0.4 to 0.56) for TUBE and SYRINGE, respectively. Comparison of ionized calcium showed a bias of 0.05 mmol/l (0.01-0.1) and -0.02 mmol/l (-0.18 to 0.14) for TUBE and SYRINGE, respectively. Between sample types, the POC yielded a bias of 5.13 mmol/l (0.18-10.09) for sodium, 0.04 mmol/l (-0.12 to 0.2) for potassium, and 0.40 mmol/l (0.12-0.68) for ionized calcium.

CONCLUSION AND CLINICAL RELEVANCE

The POC exhibited clinically negligible bias for electrolyte analysis as compared to VBG. Ionized calcium concentrations were lower in self-prepared heparinized syringes than in heparin-containing tubes, suggesting an effect of heparin concentration on ionized calcium.