Evaluation of contact activation of citrated equine whole blood during storage and effects of contact activation on results of recalcification-initiated thromboelastometry.

The research article explores the activation level of the contact pathway in citrated equine whole blood over a period of 30 minutes or less, and how this activation influences recalcification-initiated thromboelastometry results. It was found that the contact system in equine whole blood is activated ex vivo and that recalcification of blood, without any triggering agent, is not a reliable method of evaluating the hemostatic system in horses.

Methodology

• The study involved 11 healthy adult mixed-breed horses.
• Blood was taken from these horses via atraumatic jugular venipuncture into siliconized glass tubes containing a citrate anticoagulant.
• The tubes were then heated to 37°C and kept for 30 minutes or less.
• An in-vitro viscoelasticity (thromboelastometry) monitoring system was used to perform thromboelastometry.
• To determine factor XII and XI procoagulant activities, the research team used platelet-poor plasma samples taken at the same time and observed changes in the sample turbidity for 60 minutes at approximately 25°C.
• Coagulation times were calculated by fitting a line to the sharpest segment of the absorbance curve and finding its intersection with the baseline.

Analysis and Results

• The researchers applied repeated-measures ANOVA on ranks to evaluate the effect of the holding time on thromboelastometry parameters and plasma enzyme activity.
• The relationship between procoagulant activities and coagulation time was analyzed using Spearman rank-order correlation analysis.
• The results showed that thromboelastometry parameters (i.e., coagulation time, clot formation time, α angle, and maximum clot firmness) were significantly influenced by the coagulability increases during the holding period.
• The procoagulant activities of factor XII and factor XI displayed a significant increase at 30 minutes compared to 2 or 10 minutes. This indicates that sample contact activation had occurred.
• These procoagulant activities also exhibited a significant negative correlation with coagulation time, demonstrating that as the procoagulant activities increased, the coagulation time decreased.

Conclusions

• The research established that the contact system in equine whole blood is activated ex vivo.
• The study’s findings suggest that recalcification of blood without a triggering agent is not a reliable way of evaluating the hemostatic system in horses.