Validation of point-of-care devices measuring calcium (iCa), potassium (K+), and sodium (Na+) concentrations in whole blood of cattle and horses using general-purpose water quality testing equipment

To clarify whether commercially available handheld iCa, K + , and Na + devices may be used clinically, precise and accurate evaluations were performed using the handheld analyser i-STAT 1 as the standard device. Point-paired whole blood samples were obtained from 45 cattle and 19 horses. Data obtained using LAQUAtwin Ca-11C, K-11, and Na-11 correlated with those using i-STAT 1. LAQUAtwin devices were ‘compatible’ with i-STAT 1 because the frequency of differences between measurements within ± 20% of the mean was 95.5% in cattle and 94.7% in horses for iCa, 92.7% in cattle and 92.9% in horses for K + , and 100% in both for Na + . No proportional bias was observed between i-STAT 1 and LAQUAtwin Ca-11C and K-11 because the 95% CI for the intercept and slope were 0 and 1, respectively. LAQUAtwin Na-11 showed a good correlation with i-STAT 1 measurements of Na + concentrations in the whole blood of cattle and horses; however, measured values were approximately 4 mM lower with the former. Therefore, the LAQUAtwin series may be applied as a simplified system for measuring iCa, K + , and Na + concentrations in the whole blood of cattle and horses under field conditions; however, caution is required because Na + values were lower than those with i-STAT 1.