Pathophysiology of coagulation during bleeding

Background. Analysis of 99 studies found that the predictor properties of various tests to determine the blood coagulation condition, including the newest ones (thromboelastography, rotational thromboelastometry), regarding the risk of intra- and postoperative bleeding are low. The results of prothrombin time or activated partial thromboplastin time measurements can be very variable depending on the concentration of reagents and the characteristics of the analysis. That is why standard methods of screening to assess the condition of the coagulation system in all patients in the preoperative period are not recommended. Objective. To describe the features of perioperative blood clotting and management of patients. Materials and methods. Analysis of literature data on this topic. Results and discussion. Before performing invasive procedures, a careful history should be taken to determine the presence and severity of previous bleeding and to ask about antithrombotic medications. If the general hemorrhagic history is favorable, further determination of coagulographic parameters is not required. If the history is unfavorable or there is evidence of potential risk factors for bleeding (e. g., liver disease), a comprehensive coagulation study should be performed. Bleeding coagulopathy is a component of the so-called lethal triad, which also includes hypothermia and acidosis. Active administration of infusion solutions can deepen or provoke coagulopathy due to hemodilution. The use of balanced infusion solutions reduces the risk of this complication. According to some authors, the fibrinogen level <2 g/L is the predictor of bleeding probability. The causes of this condition include hyperfibrinolysis, dysfunctional fibrinogen in case of the administration of colloid solutions, increased decomposition of fibrinogen due to acidosis. Colloidal solutions (hydroxyethyl starch) increase the risk of reoperation and the need for transfusions, so their routine use is not currently recommended. Hyperfibrinolysis is a condition in which the rate of blood clot breakdown exceeds the rate of blood clot formation. As a result, hemorrhagic shock worsens and coagulopathy develops. Hyperfibrinolysis develops due to fibrinolytic agents and hypoperfusion. Tranexamic acid is used for heavy bleeding, in particular, postpartum. The WOMAN study involved 20,600 women with postpartum haemorrhage who received 1 g of tranexamic acid or placebo. Mortality due to bleeding in the tranexamic acid group was 1.2 %, and in the placebo group – 1.7 % (p=0.008). Conclusions. 1. Routine use of colloid solutions should be avoided during bleeding. 2. It is necessary to detect and eliminate anemia, hypothermia and acidosis. 3. Detection and elimination of deficiency or dysfunction of coagulation factors, hyperfibrinolysis, thrombocytopenia is an important component of bleeding prevention. 4. Reducing bleeding and improving blood clotting leads to the less need for transfusions and better outcomes for the patient.