Comparative characteristics of the hemostasis system state during hypothermic and early reactive periods of general freeze injury in rats

Aim. To study the hemostasis system state in rats during hypothermic and post-hypothermic periods. Methods. Male Wistar rats (53 individuals) were used in the study. The animals from the experimental group underwent single immersion cooling in water at a temperature of 5 °C until profound hypothermia was reached, the control group of the animals was placed in water at a temperature of 30 °C. From the animals of the first group, blood was taken immediately after reaching profound hypothermia and from the second group - 24 hours after cooling was stopped. Results. Comparative analysis of the results showed that immediately after the end of a single cold exposure, significant increase in platelet aggregation activity occured, as well as appearance of thrombinemia markers in the bloodstream and inhibition of fibrinolytic system activity. 24 hours after the experimental exposure, these parameters returned to the initial values. When assessing the activity of external and internal ways of coagulation immediately after the termination of cooling, development of hypocoagulation was established, both with routine tests and from thromboelastography. After 24-hour period, hypocoagulation, recorded immediately after reaching the sought rectal temperature, persisted. Thus, after the end of a 24-hour period after cold exposure termination, most of the parameters of hemostatic system that had deviated immediately after the end of the experiment, returned to the normal level. The delayed effect of hypothermia in such cold exposure regimen manifested only by hypocoagulative shift at the initial stages of coagulation. Conclusion. Signs of abnormal hemostasiological blood properties, recorded immediately after the cooling termination, disappear within 24 hours, and only hypocoagulation persists in the blood.

hypothermia, freeze injury, hemostasis, thrombus formation