A Brief review of AFP's "Transfusion of Blood and Blood Products: Indications and Complications"

A Brief review of : Transfusion of Blood and Blood Products:  Indications and Complications
SANJEEV SHARMA, MD; POONAM SHARMA, MD; and LISA N. TYLER, MD 
Creighton University School of Medicine, Omaha, Nebraska
Am Fam Physician. 2011 Mar 15;83(6):719-724.

http://www.aafp.org/afp/2011/0315/p719.html

     In honor of lab week, and also because I think AAFP tweeted a link to this article on Tuesday, I will be reviewing the implications and complications of blood product transfusion. Packed RBCs are whole blood that has had 250 ml of plasma removed from it. It is then filtered to remove leukocytes (which lowers the chances of a febrile nonhemolytic transfusion reaction).  It is used to treat sickle cell crisis, acute blood loss (greater than 1500 ml), or symptomatic anemia. Recent studies say that a transfusion should be done if the hemoglobin drops below 7 g/dL, and maintained between 7-9 g/dL, 8.5-9.5 g/dL in children who are stable in intensive care. Keep in mind that a unit of blood (500 ml) will increase the hemoglobin by 1g/dL and the hematocrit by 3%. Studies have shown that this aggressive approach and a strict criteria for transfusion has been effective for the patient.  
     There are two types of plasma; FFP and thawed plasma. They both contain coagulation factors, but the FFP can be used to reverse the effects of anticoagulants, whereas the thawed plasma has less factor V and VIII ( these factors are unstable when "thawed"). Many labs use it interchangeably, but you would rather use FFP for a consumption coagulopathy, such as DIC. Regardless, plasma is used in active bleeding in a patient with an elevated INR, reversal of warfarin during a hemorrhage (major or intracranial), reversal of warfarin before surgery, in microvascular bleeding during a massive transfusion, in TTP, HUS, or hereditary angioedema (when C1 esterase inhibitor is not available).
     Platelets are use to prevent hemorrhage in a patient with thrombocytopenia. It is contraindicated in TTP and HIT. A prophylactic platelet transfusion is given in stable, non bleeding patients when the platelet count is less than 10 (x 10 [to the third] per ul). If the patient has a fever above 100.4C or undergoing an invasive procedure e, we transfuse at 20 or less.  It there is no fever, but an invasive procedure or major surgery is planned, we would transfuse at less than 50. If a patient is undergoing ocular or neurosurgery  a transfusion can be considered if the count is 100 or less. 
     Cryoprecipitate is simply the precipitate that comes out when FFP is thawed. It is high in factor VIII (makes sense since it is low in thawed plasma) and fibrinogen. It is used when a patient is low in fibrinogen (duh). This happens in massive hemorrhage, Factor VIII or XII deficiency,  vWD, surgical bleeding, congenital fibrinogen deficiency, or hemorrhage after cardiac surgery.
     Transfusion reactions can be either acute or delayed, or infectious. Transfusion related infections are very rare to to the screening and preventative measures in place today. 
     Acute hemolytic reaction is caused when the patient's antibodies attack the donor RBCs.  This occurs within 24 hours or transfusion. It can occur extravascularly when the donor RBCs, coated with IgG or complement, are attacked in the liver or spleen. The more severe form, intravascular hemolysis, is due to ABO antibodies within the vessels. Symptoms include fever, chills, nausea, vomiting, dyspnea, anuria, oliguria,  dialysis, and DIC. 
     A patient could have an allergic reaction of hives or itching. An anaphylactic reaction could also occur if the patient was previously presensitized to some of the proteins (immunoglobulin, complement, etc.) in the donor plasma. The risk can be reduced by avoiding these products or having the products "washed" to remove the proteins. 
     Patients may get noncardiac pulmonary edema from a transfusion, known as TRALI (transfusion related acute lung injury). Certain antibodies will activate the immune system  causing pulmonary edema and tissue damage from proteolytic enzyme secretion.  Using male donated plasma may reduce this risk. 
     Repeated transfusions or previously pregnant patients are at increased risk of FNHTR (febrile nonhemolytic transfusion reactions). As the name states, the patient will develop a fever of at least 1C (1.8F) above normal within 24 hours of transfusion. They may show signs of rigor, chills, or discomfort.  This occurs because of cytokine release (IL-1, IL-6, IL-8, TNF), and/or antigen mediated endogenous pyrogen release. This diagnosis should be considered only after all other causes of fever have been excluded.
     If a patient gets too much product too fast, they can get "transfusion associated circulatory overload (fitting name). They present with tachycardia, cough, dyspnea, hypotension, elevated CVP, increased wedge pressure, and a widened pulse pressure. Cardiomegaly and pulmonary edema may also be seen. 
     The main form of delayed reaction is "transfusion related graft vs host disease". The tissue and organs are attacked by the donor lymphocytes. It if often fatal. High risk patients are those who are  immunocompromised, have been of fludarabine, chemotherapy, cytotoxic drugs, have had hodgkin's disease, a stem cell transplant, or are receiving blood from a relative.  Gamma irradiation of the blood products can reduce the risk.