Effects of syringe material and temperature and duration of storage on the stability of equine arterial blood gas variables.

The study examined the effects of syringe material and temperature, along with duration of storage on the stability of partial pressures of arterial oxygen (PaO2), arterial carbon dioxide (PaCO2) and pH measurements in equine carotid arterial blood samples. It found that for accurate analysis, PaO2 samples should be analysed within 10 minutes or stored in glass syringes, on ice, for up to 2 hours, while PaCO2 and pH measurements can be done on samples stored in any syringe material at room temperature for up to an hour.

Research Methodology

• The research conducted was a prospective observational study that spanned over 19 days in duration.
• Four clinically normal Thoroughbred or Thoroughbred-cross horses were selected for the study, which included three geldings and one mare. Their mean age was 6.25 years, and they ranged from 5 to 7 years.
• Identical blood samples were taken from these horses at two separate times from their carotid arteries.
• The blood samples were then placed in syringes made from three different materials: glass, plastic, and polypropylene.
• PaO2, PaCO2, and pH measurements were performed on the blood from each type of syringe at three different times: 10, 60 and 120 minutes after sample collection.
• These samples were either stored at room temperature (around 20 degrees Celsius) or in iced water (around 0 degrees Celsius).
• The data collected was then analysed using anova and a split plot model.

Summary of Key Findings

• The kind of syringe used, storage temperature, and time before analysis all affected PaO2 considerably.
• PaCO2 results remained unaffected by the type of syringe or storage temperature, but the duration of storage affected them significantly over 120 minutes.
• The temperature of storage and duration prior to analysis both significantly affected pH values.
• The effect of the syringe material did not influence pH values.
• Significant interactions were noted between these variables.

Conclusions and Recommendations

• The study revealed that equine arterial blood gas determination has different sensitivity to storage conditions compared to other veterinary species.
• For accurate analysis of PaO2, samples need to be analysed within 10 minutes or taken into glass syringes and stored on ice, to be analyzed within 2 hours post-sample collection.
• PaCO2 and pH measurements can be performed on samples stored in glass, plastic or polypropylene syringes at room temperature for up to 1 hour post-sampling.