Evaluation of the i-STAT portable point-of-care analyzer for determination of blood gases and acid-base status in newborn calves

OBJECTIVE: To validate the i-STAT, a portable hand-held analyzer that allows point-of-care measurement of blood gases, acid-base, lactate, and other blood variables in food animal practice for analysis of blood samples of newborn calves. DESIGN: Prospective observational study. SETTING: University teaching hospital. MEASUREMENTS AND MAIN RESULTS: A total of 271 venous blood samples were analyzed for PvO2 , PvCO2 , pH, base excess (BE), HCO3 , venous saturation of oxygen (SvO2 ), and total carbon dioxide (TCO2 ) using an i-STAT and a Rapidlab 248 bench top analyzer that served as the reference method. l-lactate was measured using the i-STAT as well as photometrically. Results from the i-STAT and the reference methods were compared. The analytes BE, HCO3 , and TCO2 showed a constant systematic error across the entire range with 2.3, 1.9, and 2.0 mmol/L lower values, respectively, than the values measured by the reference method. Based on the combined inherent imprecision of the 2 analyzers and after correcting the influences of systematic errors, the PvO2 , HCO3 , and SvO2 were within the acceptable limits in 76% to 91% of the cases. Ninety-five percent of the measurements of PvCO2 and BE were within acceptable limits. CONCLUSIONS: The overall performance of the i-STAT was good except for BE, HCO3 , and TCO2 , thus limiting its usefulness in clinical studies. However this hand-held device allows rapid, reliable, and accurate point-of-care blood analyses and thus can be useful in bovine practice