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Dilutional Coagulopathy

 

Studies have shown that 50% of patients who receive massive transfusions develop a dilutional coagulopathy with an elevation of the INR > 2.0. Thirty-three percent have platelet counts less than 50,000. This dilutional coagulopathy may be further compounded by a disseminated intravascular coagulopathy, such as can be seen with severe abruption, prolonged intrauterine death and amniotic fluid embolus.

During massive transfusions and a clinical coagulopathy, thrombocytopenia less than 75,000/mm³ should be treated with platelet concentrates. Contrary to some older references, the number of units of RBC's that have been transfused is not an accurate predictor regarding the need for platelet transfusions or similarly, for fresh frozen plasma. Treatment must be based on laboratory results combined with the clinical picture.

Hypofibrinoginemia is one of the earliest abnormalities to occur in the massive transfusion scenario. Levels should be maintained ≥ 1.0g/l with FFP or, alternatively, cryoprecipitate if fluid overload is an issue. However, in the majority of cases of PPH, volume resuscitation is also an issue, particularly during the early part of the resuscitation. Therefore, FFP is the better choice as it contains twice the amount of fibrinogen per unit as compared to cryoprecipitate. 

Although factors V and V111 are the labile factors in stored blood, they are rarely the cause of bleeding secondary to massive transfusion. This is due to the fact that factor V and factor V111 levels less than 30% of normal are adequate for hemostasis. However, although they are not the primary cause of bleeding, lower levels may intensify bleeding from other causes such as a decreased platelets. Therefore, it is important to ensure that the platelet count is above 70,000 during active bleeding, as noted above.  In addition, it is extremely important to remember that hypothermic patients will continue to have clinically significant bleeding despite adequate blood, plasma and platelet transfusions. Therefore, avoidance of hypothermia is critical to the correction of a coagulopathy. Once again this underscores the need to aggressively treat hypothermia in these patients.

 

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