3: Blood Products Flashcards
What effect does cold temperature have on blood clotting?
It results in poor clotting
[Patient needs to be warm to clot correctly]
What is deficient in stored blood, leading to a left shift (increased affinity for oxygen)?
2,3-DPG
What is the most common transfusion reaction?
Febrile nonhemolytic transfusion reaction
What causes an acute hemolysis reaction following a blood transfusion?
ABO incompatibility
[Antibody mediated]
Dilutional thrombocytopenia occurs after how many units of packed red blood cells (PRBC)?
10 units of PRBC
[UpToDate: In an adult, each 10 to 12 units of transfused RBCs are associated with a 50% fall in the platelet count; thus, significant thrombocytopenia can be seen after 10 to 20 units of blood, with platelet counts below 50,000/microL. For replacement therapy in this setting, 6 units of whole blood derived platelets or one apheresis concentrate should be given to an adult; each unit should increase the platelet count by 5000/microL or 30,000/microL for a full 6 unit adult dose.]
What is the treatment for an acute hemolysis reaction following a blood transfusion?
- Fluids
- Diuretics
- HCO3
- Pressors
- Histamine blockers (Benadryl)
[UpToDate: When a hemolytic transfusion reaction (HTR) occurs during or immediately after transfusion, it is labeled an acute HTR, is a medical emergency requiring immediate intervention, and is almost always a result of complement-mediated intravascular hemolysis caused by preformed antibodies in the recipient’s plasma to the donor’s red blood cells (RBCs). This medical emergency results from the rapid destruction of donor RBCs by preformed recipient antibodies, usually anti-A or anti-B but occasionally anti-Rh or anti-Jka, capable of fixing complement. Rapid intravascular hemolysis may lead to disseminated intravascular coagulation (DIC), shock, and acute renal failure due to acute tubular necrosis.
The classic presenting triad of fever, flank pain, and red or brown urine (ie, hemoglobinuria) is rarely seen; fever and chills may be the only manifestation, except in patients under anesthesia, or in coma, for whom DIC may be the presenting mode.
When an acute HTR is suspected, the transfusion must be stopped immediately, the patient should be hydrated with normal saline, and vigorous supportive care to maintain the patient’s airway, blood pressure, urine output, and heart rate applied while serologic investigation is undertaken.]
Urticaria following blood transfusion is usually caused by what?
Recipient antibody reaction against donor plasma proteins
[Or IgA in an IgA-deficient recipient]
[UpToDate: Urticarial (allergic) transfusion reactions (UTRs) occur when soluble allergenic substances in the plasma of the donated blood product react with preexisting IgE antibodies in the recipient. This causes mast cells and basophils to release histamine, leading to hives or urticaria. However, other mechanisms may be involved.
An UTR is the only transfusion reaction in which the remainder of the blood product can be administered. However, the transfusion should first be stopped and if the urticaria is extensive, 25 to 50 mg of diphenhydramine can be given orally or intravenously. Rarely, a UTR may be the first sign of a more serious reaction. If the urticaria wanes and dyspnea, hypotension, and anaphylaxis are absent, the transfusion may be resumed.
The incidence of allergic transfusion reactions ranges from 1% to 3%, with growing evidence that premedications administered to prevent such reactions are ineffective. However, two small studies suggest that washing pooled whole blood-derived and apheresis platelets decreases such reactions. In a retrospective cohort study of 179 individuals who received unmanipulated platelets and subsequently received concentrated (ie, plasma removed) and/or washed apheresis platelets, the incidence of allergic transfusion reactions was 5.5%, 1.7%, and 0.5% for unmanipulated, concentrated, and washed platelet products, respectively.]
Donated blood is screened for which 6 viruses?
- HIV
- Hepatitis B
- Hepatitis C
- Human T-Cell Lymphotropic Viruses (HTLV)
- Syphilis
- West Nile virus
What 3 lab results are suggestive of an acute hemolytic reaction following a blood transfusion?
- Haptoglobin less than 50 mg/dL (binds hemoglobin and then gets degraded)
- Free hemoglobin greater than 5 g/dL
- Increase in unconjugated bilirubin
[UpToDate: Laboratory testing for AHTR includes the following, which is done in consultation with the transfusion service:
- Repeat ABO compatibility testing
- Additional antibody studies if ABO incompatibility is excluded
- Repeat crossmatch with pre-and post-transfusion specimens using an indirect antiglobulin (IAT) method
- Direct antiglobulin (Coombs) testing (DAT)
- Observation of the serum for pink color and analysis for free hemoglobin
- Serum haptoglobin, lactate dehydrogenase (LDH) and unconjugated bilirubin levels to document hemolysis
- Coagulation testing for disseminated intravascular coagulation (DIC) if the patient has increased bleeding
- Observation of the urine for pink color and analysis for free hemoglobin
- Serial hemoglobin levels to determine the severity of hemolytic anemia and possible need for additional red blood cell (RBC) transfusions]
Which virus is important to be screened for in blood given to low-birth-weight infants, bone marrow transplant patients, and other transplant patients?
Cytomegalovirus
[CMV-negative blood is required for these immunocompromised patients]
In anesthetized patients, transfusion reactions may present as what?
Diffuse bleeding
[UpToDate: The classic presenting triad of fever, flank pain, and red or brown urine (ie, hemoglobinuria) is rarely seen. Fever and chills may be the only manifestations and, in patients under anesthesia or in coma, DIC may be the presenting mode, with oozing of blood from puncture sites and hemoglobinuria.]
Anaphylaxis following blood transfusion is usually caused by what?
Recipient antibody reaction against donor IgA
[This occurs in an IgA-deficient recipient]
[UpToDate: Rapid onset of anaphylaxis, manifested by shock, hypotension, angioedema, and respiratory distress, in a transfusion recipient requires rapid recognition and concomitant action, since it is a life-threatening occurrence. An anaphylactic transfusion reaction (ATR) may occur within a few seconds to a few minutes following the initiation of a transfusion that contains plasma, red cells, platelets, granulocytes, cryoprecipitate, or gamma globulin. An ATR is not generally seen following the administration of normal serum albumin, plasma protein fraction, or coagulation factors. It is the rapid onset that is characteristic of an ATR.
Severe anaphylactic reactions have a reported incidence of 1:20,000 to 50,000, but are believed to be more common.
One well-characterized mechanism for this reaction is the presence of class-specific IgG anti-IgA antibodies in patients who are IgA deficient. Selective IgA deficiency is not uncommon, occurring in about 1 in 300 to 500 people. Fortunately, few IgA deficient patients develop antibodies.]
Febrile nonhemolytic transfusion reaction is usually caused by what?
Recipient antibody reaction against donor WBCs
[Treat by stopping transfusion and by using a WBC filter for subsequent transfusions]
[UpToDate: It has been proposed that an interaction between donor leukocytes and recipient antibody leads to interleukin-1 (IL-1) release from donor leukocytes or recipient monocytes. IL-1 can then cause fever by stimulating prostaglandin E2 production in the hypothalamus. Two observations are compatible with the primary role for donor leukocytes: cytokine accumulation is reduced by prestorage leukocyte reduction, and leukoreduction is an effective preventive therapy.]
Transfusion-related acute lung injury following blood transfusion is usually caused by what?
Donor antibodies to recipient’s WBCs
[Rare]
[UpToDate: The generally accepted theory for TRALI pathogenesis is that it occurs via a two-hit mechanism.
- Neutrophil sequestration and priming – The first hit involves neutrophil sequestration and priming in the lung microvasculature, due to recipient factors such as endothelial injury. Priming refers to shifting of neutrophils to a state where they will respond to an otherwise innocuous or weak signal. Endothelial cells are thought to be responsible for both the neutrophil sequestration (through adhesion molecules) and priming (through cytokine release). Generally these events are coupled and exist prior to the transfusion, although there may be circumstances in which they can occur as a result of the transfusion.
- Neutrophil activation – The second hit is activation of recipient neutrophils by a factor in the blood product. Activation is associated with the release from neutrophils of cytokines, reactive oxygen species, oxidases, and proteases that damage the pulmonary capillary endothelium. This damage causes inflammatory (non-hydrostatic) pulmonary edema. Transfused factors responsible for host neutrophil activation can include antibodies in the blood component directed against recipient antigens, or soluble factors such as bioactive lipids that can activate neutrophils. Donor anti-leukocyte antibodies can bind to antigens on recipient neutrophils or possibly to other cells such as monocytes or pulmonary endothelial cells; this is referred to by some authors as immune TRALI. Bioactive lipids and other soluble factors in the transfused blood component can act as biological response modifiers (BRMs); TRALI resulting from these non-antibody BRMs is sometimes referred to as non-immune TRALI.]
What is the most common bacterial contaminate of transfused blood?
Gram negative rods
[Usually E. coli]
