What do you think the D-dimer will be in this situation? Would it be a useful test here?
One would expect the D-dimer to be relatively low in this situation --it is not uncommon for surgical patients to have mildly elevated D-dimer titers (such as 1:8, especially post-operatively). This clinical scenario is one of a patient in hemorrhagic shock due to pure blood loss. If you read the literature on DIC, ischemia is on the "laundry list" of things that can precipitate DIC. In reality, ischemia rarely causes DIC. The above laboratory findings in this case are usually due to another phenomenon (see answer to question below). Obtaining a D-dimer value would help determine if DIC was occurring, although we generally know the value will be low in this scenario.
If the D-dimer is 1: 8, what blood products would be in order?
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 | Fresh frozen plasma |
Red cells, if obvious ongoing blood loss is occurring, otherwise a hematocrit of 30% (especially one that is diluted--see below) is quite good in this case.
Platelets, although a diluted platelet count of 60,000/microliter is also relatively good, and so one may wait until the count decreases a little further.
If one evaluates all of the above labs, we notice that all of the values are low. Given the clinical scenario here, it is most likely that these values reflect a "diluting" effect--platelets and coagulation factors are not only being used, but they are being diluted out by crystalloid solutions administered to the patient. The low fibrinogen and prolonged coagulation times reflect the fact that all of the clotting factors are low in this patient, or at least diluted to the point that the patient may not be clotting effectively. Therefore FFP is the product of choice here, since it contains all of the factors needed for clotting.
Platelets may also be needed, since they are being used in the body's attempt to clot the ruptured aorta.
Would you give cryoprecipitate?
The question of whether or not to give cryo is somewhat subjective. One blood bank physician will say that the fibrinogen is just a reflection that all coagulation factors are low, and since the patient is not in DIC, the fibrinogen is not disproportionately affected. Another blood bank physician may feel that a serum fibrinogen concentration less than 60 mg/dL is always a reason to give cryoprecipitate, although in this case, the other clotting factors contained in FFP are needed as well.
What is the main mechanism that leads to the above lab values in this case?
A dilutional coagulopathy resulting from a scenario where urgent fluid resuscitation and massive transfusion is required. When a patient is in hemorrhagic shock, the quickest way to fluid resuscitate them is with crystalloids such as normal saline. In the operating room, crystalloid administration to maintain tissue perfusion is a main principle. Patients with ruptured aortas or severe fractures from trauma can lose entire blood volumes. After time, the amount of crystalloid can effectively dilute out coagulation factors unless they are replaced with FFP.
Some texts also emphasize the fact that hypothermia can exacerbate decreased function of coagulation factors and platelets. One may optimize the non-surgical hemostasis, therefore, by making sure that the patient is warm.
