Evaluation of the i-STAT Alinity v in a veterinary clinical setting

Abstract

Many point-of-care (POC) analyzers are available for the measurement of electrolytes and acid-base status in animals. We assessed the precision of the i-STAT Alinity v, a recently introduced POC analyzer, and compared it to 2 commonly used and previously validated POC analyzers (i-STAT 1, Stat Profile pHOx Ultra). Precision was evaluated by performing multiple analyses of whole blood samples from healthy dogs, cats, and horses on multiple i-STAT Alinity v analyzers. For comparison between analyzers, whole blood samples from dogs and cats presented to the emergency room were run concurrently on all 3 POC instruments. Reported values were compared by species (dogs and cats only) using Pearson correlation, and all values from all species were analyzed together for the Bland-Altman analysis. Results suggested that the i-STAT Alinity v precision was very good, with median coefficients of variability <2.5% for all measured parameters (except the anion gap), with variable ranges of coefficients of variation. In addition, good-to-excellent correlation was observed between the i-STAT Alinity v and i-STAT 1, and between the i-STAT Alinity v and Stat Profile pHOx Ultra for all parameters in both cats and dogs, respectively. In this cohort, the i-STAT Alinity v had clinically acceptable bias compared to the currently marketed analyzers and can be used for monitoring measured analytes in cats and dogs, although serial measurements in a single animal should be performed on the same analyzer whenever possible.

Keywords: blood gas; cats; dogs; electrolytes; emergency; point-of-care..

Figure 1.

Bland–Altman analysis of glucose concentration, compared between 2 point-of-care analyzers, for all values <6.66 mmol/L (120 mg/dL). The x-axis indicates the mean value for glucose (mmol/L), and the y-axis displays the percent difference in results between the i-STAT Alinity v and Stat Profile pHOx Ultra. The solid line represents the bias (8.48%), and the dashed lines represent the 95% confidence interval of the bias (–3.04% to 8.49%).

Figure 2.

Bland–Altman analysis of oxygen concentration, for values <16.0 kPa (120 mmHg). The x-axis indicates the mean value for partial pressure of oxygen (PO₂, kPa), and the y-axis display the difference in results between the i-STAT Alinity v and Stat Profile pHOx Ultra. The solid line represents the bias (–10.2%), and the dashed lines represent the 95% confidence interval of the bias (–29.4% to 9.0%).