Blood transfusions are life-saving treatment options, to the point where informed consent is not necessarily required if it has to be done in an emergency to save a person’s life.
Additionally, blood banks have developed a sophisticated variety of blood products to ensure that they’re free of infection and compatible with a recipient’s blood type.
To understand them all, let’s review the normal components of blood. When blood is spun down in a centrifuge, the layers separate out.
The first layer is the cellular component, which accounts for 45% of blood, and includes red blood cells, or RBCs, white blood cells, or WBCs, and platelets.
Second is the acellular component, also called plasma, which accounts for 55% of blood.
Plasma is composed of everything that isn’t a cell, including proteins like albumin, electrolytes like sodium, molecules like glucose, coagulation factors like factor 8, and lipoproteins like low-density lipoprotein, or LDL.
Now, the main blood products that can be transfused are packed red blood cells, or PRBCs, which are RBCs that had most of their surrounding plasma removed, fresh frozen plasma, or FFP, which is made of all the coagulation factors together, platelets, prothrombin complex concentrates, or PCCs, which are composed of factors 2,7,9 and 10, cryoprecipitate, which is made of fibrinogen, von willebrand factor, and factors 8 and 13 and finally pure coagulation factor concentrates, like pure factor 8.
Alright, so acutely bleeding or anemic patients can require PRBC transfusions.
To do that, a sample of their blood is taken, and the bank performs a “type and screen”.
Type refers to looking at the recipient’s RBCs surface antigens, which include their ABO, Rh or D-antigens and checking if they’re compatible with the donor’s RBCs.
Screen refers to looking for antibodies in the recipient’s plasma, and if they’re present, then making sure that the donor RBCs don’t have antigens that would get bound by those antibodies. This is done to prevent a transfusion reaction.
If the donor and recipient are compatible, the PRBC transfusion is given.