Comparison of two analyzers for measurement of plasma total carbon dioxide concentration in horses.

The research compares the accuracy of two analyzers in measuring the total Carbon Dioxide (CO₂) concentration in the blood plasma of horses, finding that the less expensive Analyzer B provides suitable precision and linearity for such measurements.

Methodology

• The study involved a sample size of 147 horses split in three groups: six healthy untrained horses, six trained Standardbreds participating in a simulated race protocol, and 135 trained Standardbreds at a racetrack.
• Blood samples were taken from the jugular vein of all horses. Subsequently, two analyzers (referred to as analyzer A – a commonly used analyzer, and analyzer B – a less expensive analyzer) were used to measure plasma total Carbon Dioxide (ctCO₂) concentration in each sample.
• The evaluation and validation of both analyzers proceeded in accordance with guidelines set by the Clinical and Laboratory Standards Institute. The characterization of linearity, total analytic error, and bias estimation were factors assessed during validation.

Results

• The total analytic error was 0.58 mmol/L for analyzer A and 0.49 mmol/L for analyzer B when measuring a standard containing 36.0 mmol of CO₂ per liter.
• Furthermore, results showed that a decrease in plasma protein concentration by 1g/L corresponds to an increase in ctCO₂ measured with Analyzer B of 0.065 mmol/L.
• A difference plot signified that Analyzer B produced values that were approximately 2.7% higher than those from Analyzer A. This finding was based on 103 samples taken from the six trained and exercised Standardbreds. The mean plasma protein concentration for these samples was 67g/L.

Conclusions

• The study concluded that Analyzer B has adequate precision and linearity for measuring ctCO₂ from 5 to 40 mmol/L and is thus appropriate for determining ctCO₂ in equine plasma.
• However, allowances should be made for potential changes in plasma protein concentration when using Analyzer B, as these changes could affect the accuracy of the ctCO₂ measurement.