The Effect of Inadequate Presample Blood Volume Withdrawal from Intravenous Catheter and Extension Sets on Measured Circulating L-Blood Lactate Concentration in Horses Receiving Lactated Ringer’s Solution.

This research study focuses on the necessity of initial blood withdrawal from intravenous catheter and extension sets in horses before measuring their circulating L-Blood Lactate concentration to ensure accuracy. The study found that withdrawing 15mL of blood from an extension set filled with Lactated Ringer’s solution (LRS) increases the accuracy of Lactate concentration measurements.

Research Objectives and Methods

• The researchers sought to determine the proper volume of blood to withdraw from an Intravenous (IV) catheter and extension sets installed in horses in order to get an accurate blood lactate concentration (BLC). These measurements are often taken in veterinary services from IV catheters.
• The study involved thirty-three adult horses that were hospitalized receiving continuous LRS infusion.
• Five sequential blood samples of 5 ml each were taken after disconnecting the LRS and its attached extension set. They compared these to three samples acquired through direct venipuncture of the contralateral jugular vein.
• A portable blood lactate analyzer was used to evaluate the lactate concentrations of the samples.
• Reasons for hospitalization, horses’ breed, age and gender were considered in the analysis, using a linear mixed model.

Results

• Comparing the amounts of blood lactate in the samples taken from the IV catheter and those taken directly, the study found that the first two samples from the IV catheter showed higher concentrations of blood lactate.
• The biggest difference seen between the third sample and subsequent ones was 0.34 mmol/L, in a confidence interval of 95% with an upper limit of 1.12 mmol/L. However, samples collected directly did not show this elevated level of lactate concentration.

Conclusion

• Researchers suggest that 15mL of blood should be withdrawn from the extension set attached to an IV catheter before sample collection for the analysis in order to get accurate results on the lactate concentration in the blood of the animals.
• As the extension set used in the study could hold up to 5.9 mL, the advised volume of 15 mL ensures that the sample obtained is not contaminated by the LRS solution that was infused before.