The evoluation of validity aportable clinical analyzer for the determination of blood urea, nitrogen plasma creatinine, sodium,chloride, potassium in cattle

In recent years, hand-held analyzers, also known as point-of-care (POC) devices, have been used in veterinary medicine. The i-STAT, a POC device, has been used extensively in bovine medicine. The purpose of this study was to determine the validity of the i-STAT in assessment of blood urea nitrogen (BUN), creatitine, sodium, chloride, and potassium concentrations using plasma blood urea nitrogen, creatitine, sodium, chloride, and potassium measured by a conventional auto-analyzer. Ninety eight cattle with various diseases were used in this study. Blood samples were collected from the jugular vein of all cattle into vacutainers including lithium heparin. A portion of blood samples was used for immediate determination of BUN, creatitine, sodium, chloride, and potassium concentrations using the i-STAT. The remaining blood was immediately centrifuged to harvest plasma. Plasma BUN, creatitine, sodium, chloride, and potassium concentrations were measured by an auto-analyzer. The i-STAT and auto-analyzer were calibrated and used in accordance with their manufacturers' specifications. Blood and plasma electrolyte data were subjected to student t-test for comparison, the Passing-Bablok regression and the Bland-Altman plot for reliability, and receiver operating characteristics curves for sensitivity (Se) and specificity (Sp). The receiver operating characteristics (ROC) curves were developed at the cut-off plasma creatinine > 2mg/dL and plasma potassium concentrations of <3.9 mmol/L (hypokalemia) and >5.8 mmol/L (hyperkalemia); to determine sensitivity (Se) and specificity (Sp) of the i-STAT. BUN and plasma creatitine concentrations were lower than their concentrations in blood. Plasma concentrations of potassium (4.39 vs. 4.2 mmol/L; P < 0.0001) and chloride (100.30 vs. 99.4 mmol/L; P < 0.04) were greater than their concentrations in blood. Plasma and blood sodium concentrations were similar (136.95 vs. 136.8 mmol/L). The i-STAT results were highly correlated with the auto-analyzer results (r= 0.979, 0.987, 0.970, 0.922, and 0.866 for BUN, creatinine, potassium sodium and chloride, respectively). The mean bias (blood concentration - plasma concentration) was 1.03 for BUN, 0.15 for creatinine, -0.20 for potassium, -0.16 for sodium, and -0.87 for chloride. The i-STAT had 100% Se and 91.9 % Sp for assessing creatinine. The i-STAT showed 100 % Se and 91.94 Sp to detect hypokalemia and 100 % Se and 100 % Sp to detect hyperkalemia. The i-STAT yielded results that were in agreement with the auto-analyzer, with negligible biases in measurement of plasma creatinine, potassium, sodium, and chloride concentrations. The i-STAT overestimated BUN concentration and had constant and proportional biases.