Effect of sample handling and storage time on the stability of total CO2 in equine plasma.

The study explores how the stability of total CO2 concentration in horse plasma can be affected by storage conditions and handling procedures. It concludes that horse blood samples should be centrifuged immediately after collection and analysed quickly to maintain accuracy in CO2 readings.

Objectives and Procedure

• The primary goal of this study was to gauge the stability of total CO2 concentration in plasma in horses over a period of 5 days. The research was established within the context that ctCO2 stability can be influenced by factors such as storage temperature and method of handling during sample processing.
• The researchers wanted to find out whether a delay in centrifugation can increase the rate at which plasma CO2 decreases over time. To test this, blood was collected from 6 adult horses and placed into 3ml plastic Vacutainer tubes.
• The blood samples were then randomly assigned for immediate centrifugation or after being stored. The ctCO2 was measured at different intervals – 0, 24, 48, 72, and 96 hours after collection using a NOVA-4 analyser.

Results and Analysis

• The study found that the CO2 levels in the plasma decrease linearly over time during storage at a temperature of 4°C. Furthermore, the decrease in ctCO2 levels was more rapid, about -0.28 mmol/l/day, when centrifugation was delayed compared to immediate centrifugation (< -0.10 mmol/l/day).
• Assessment of the sequence of sample analysis also showed a notable effect on the CO2 values when measured three times: the second and third measurements were 0.31 and 0.41 mmol/l lower than the first measurement, respectively.

Conclusions and Recommendations

• From the results, the study’s authors concluded that for accurate ctCO2 values, blood samples from horses should be centrifuged immediately after collection and analysed as soon as possible. This finding resolved the confusion concerning the effect of centrifugation on ctCO2 measurements.
• They also noted that a failure to centrifuge or delaying ctCO2 measurements after centrifugation led to significantly lower readings than the true value. This is crucial information for researchers, veterinarians, and others who must handle equine blood samples and conduct CO2 readings.