Blood Components 101

This will serve as a guide for the specific indications, storage requirements and stability of the different blood components.

Storage

Whole Blood, Packed Red Blood Cells: 1-6 degrees Celsius.

Plasma, Cyroprecipitated AHF: -18 degrees Celsius.

Platelets: 20-24 degrees Celsius with continuous gentle agitation.

Granulocytes: 20-24 degrees Celsius without agitation.

Stability

Whole Blood: When refrigerated a unit of whole blood has a shelf life between 21-35 days depending on the additive that is used. Must be transfused within 4 hours when at room temperature.

Packed Red Cells: Packed red cells are stable for up to 42 days refrigerated, but they can also be frozen with glycerol as a cyroprotectant for up to 10 years. They must be deglycerolized by washing and thawed prior to transfusion and must be transfused within 24 hours once thawed.

Platelets: Platelets have a shelf live of only 5 days. Some hospitals and clinics are extending the shelf life out to 7 days with continuous bacterial testing to ensure there is no contamination.

Plasma: Plasma products must be processed and frozen within 8 hours of collection and are stable for 12 months. Once thawed they must be transfused within 24 hours.

Thawed Plasma: Has an expiration of 5 days.

Cryo: Cyro AHF once pooled and frozen has a stability of up to 12 months.

Granulocytes: Granulocytes must be transfused within 24 hours after donation.

Constituents

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Whole Blood: Used to replace the loss of both RBC mass and plasma volume. The product is 550-600 mL of whole blood, with a hematocrit of about 40%.

Packed Red cells: Usually the red cell product of choice. 330 mL of red cells, hematocrit of about 55-65% with an additive solution.

 

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Platelets: Platelets derived from whole blood must contain at least 5.5×10^10 platelets in 40-70 mL of plasma in at least 90% of the units tested. Platelets donated through apheresis must contain at least 3×10^11/L platelets in 100-500 mL of plasma. One apheresis platelet collection is equivalent to six pooled random donor platelet concentrates.

 

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Plasma: Can be derived from whole blood or apheresis collection. Plasma contains albumin, coagulation factors, fibrinolytic proteins, and immunoglobulins. Fresh frozen plasma (FFP) derived from whole blood is usually 220-300 mL and units derived from apheresis usually contain 400-600 mL. The plasma must be frozen within 8 hours of collection.

 

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Cryoprecipitated Antihemophilic Factor (AHF): AHF is prepared from FFP. It is slowly thawed, then refrozen within one hour of thawing. AHF typically contains 5-20 mL of plasma with 80-120 U/concentrate of Factor VIII, 150-250 mg/concentrate of fibrinogen, 40-70% of vWF, and 20-30% of Factor XIII that would normally be present in FFP. Making it the treatment of choice for Von Willebrands Disease and Hemophiliacs.

Indications

Red Cells

Red cell transfusions are used to treat hemorrhage and to improve oxygen delivery to tissues. The decision to transfuse red cells should be based on the patients clinical condition. Indications for red cell transfusion include acute sickle cell crisis, acute blood loss of greater than 30% of blood volume, or patients with symptomatic anemia that can’t function without red cell repleting. The threshold for transfusion of red cells should be a hemoglobin of 7 g/dL in adults and children. Maintenance can be at a level of >7-9 g/dL.  One unit of red cells should increase the hemoglobin by 1 g/dL and hematocrit by 3%.

Washed Red Cells

Washed red cells are washed with saline to remove any residual plasma proteins. These are used for patients with a history of allergic transfusion reactions. These patients have an IgA deficiency and have developed anti-IgA.

Leukocyte Reduced

Leukocyte reduced red cells decrease the incidence of febrile transfusion reactions. They are indicated for those at high risk of transfusion-associated GVHD or transfusion-related immune suppression. For a unit to be considered leukocyte reduced, there must be less than 5×10^6 leukocytes.

Irradiated Red Cells

Used for patients with a history of febrile transfusion reactions or patients that are immunocompromised immediately after an allogeneic bone marrow or stem cell transplant. Patients at risk for HLA-GVHD will receive irradiated red cells.

Plasma

Plasma transfusion are recommended for patients with active bleeding and an international normalized ratio (INR) greater than 1.6. Its indicated for patients on anticoagulant therapy that are undergoing an invasive procedure. Plasma should not be administered for a high INR without active bleeding. Plasma is indicated for patients with inherited clotting factor deficiencies for which there is no safe recombinant factor available. Those factors are II, V, X, and XI. Plasma is used as an emergent reversal of warfarin (coumadin) toxicity to prevent intracranial hemorrhage. It is also used in acute disseminated intravascular coagulation (DIC) or other thrombotic microangiopathies such as thrombotic thrombocytopenic purpura (TTP) or hemolytic uremic syndrome (HUS). Plasma is often times transfused with red cells during massive transfusions; with the definition of massive transfusion being greater than 5,000 mL in an adult of average weight (70 kg).

Platelets

Platelet transfusions are indicated to prevent hemorrhage in patients with thrombocytopenia or those with functional platelet defects. Contradictions for platelet therapy are patients with TTP and heparin-induced thrombocytopenia (HIT) as transfusion in these clinical situations can result in exacerbation of thrombosis. Platelet transfusions can be used prophylactically in invasive surgeries with no active bleeding and commonly used in active bleeding situations along with transfusion of FFP and red cells. One unit of apheresis platelets should increase the platelet count in adults by 30-60×10^9/L.

Transfusion of neonates is complicated and should be based on upon clinical reasons with consideration to the platelet count. If the count is <20×10^3/mL, you should always transfuse if possible. When you reach 20-30×10^3/mL you should consider transfusion, but weigh all possibilities. In a case of active bleeding, transfusion is absolutely appropriate, but all factors should be considered. Transfusion is also indicated in there is signs of a coagulation disorder, intraventricular or intraparenchymal cerebral hemorrhage, an invasive procedure, or if there is alloimmune neonatal thrombocytopenia.

Cryoprecipitate AHF

Cryo contains high concentrations of factor VIII and fibrinogen and is used especially in cases of hypofibrinogenemia. Hypofibrinogenemia is typically seen in the setting of massive hemorrhage or in a consumptive coagulopathy such as DIC. Indications for cyroprecipitate AHF are factor VIII and factor XIII deficiency, congenital fibrinogen deficiency, and von Willebrand disease.

 

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Granulocyte Pheresis

Indicated for patients with fever, neutropenia, septicemia or an antibiotic resistant bacterial infection.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Blood System Portfolio: ABO Group

The ABO blood group system was first discovered in 1901 by Karl Landsteiner. In 1902 Sturli and Von Decastello discovered the AB group. The ABH antigens do not develop until about 6 weeks of fetal life and the concentration of antigens increases until 3-4 years of age and level out. Antibodies to the ABO blood group are naturally occurring, meaning that the body will develop immunity without previous exposure to the other blood type antigens. They are high titer antibodies and will bind an activate complement in vivo. Antibodies are not able to be detected in serum until 3-6 months of age and titers decrease markedly after the age of 65.

When classifying an individuals blood type is it typically referred to by the forward and reverse groupings. For example, if someone is blood type A, they will have naturally occurring antibodies to type B. That is why it is very important when selecting blood products for a patient that every precaution is taken to match the blood types as best as possible. The ABO antibodies are clinically significant and the hemolytic reactions are immediate and hemolytic.

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The ABH genes that encode for the ABO blood group system encode for a glycosyl transferase enzyme that adds a specific monosaccharide to a precursor substance which results in a distinguishable antigenic structure. The B gene encodes for a-3-D-galactosyltransferase which adds the D-galactose sugar resulting in the B antigen on the RBC surface. The A gene encodes for a-3-N-acetylgalactosaminyltransferase which adds the N-acetyl-D-galactosamine sugar resulting in the A antigen. The H gene encodes for the a-2-L-fucosyltransferase which adds the L-fucose sugar resulting in the H antigen.

The ABH antigens are membrane bound glycolipids. All ABH antigens have type 2 precursors that are chains linked by a 1,4 linkage. To have an A antigen, the H antigen MUST be present. Same with the B antigen, but absence of the A and B antigens with the H antigen present is considered type “O”. The ABO genes are located on chromosome #9 and there are 4 major alleles; A1, A2, B and O. A1 is codominant with B. A2 is recessive to A1, but also codominant with B. O is recessive to all other alleles. The H gene is located on chromosome #19 and there are 2 alleles that can be expressed. H encodes for fucosyltransferase, and “h” is an amorph. Individuals that have the phenotype “hh” are considered to have the bombay phenotype and are extremely rare. These individuals will not produce the H antigen, therefore there are no A or B antigens as well. It doesn’t matter if the genes for the A and B antigens are present, without the H antigen, there can be no A or B antigen production.

ABO antibodies are primarily IgM that react at room temperature and sometimes at 37 degrees celsius. The antibodies follow Landsteiners law which states an individual possesses antibodies to ABO antigens that are absent from their own cells. As mentioned above, the forward and reverse grouping should agree. If there is a discrepancy there is further testing that can be done to distinguish the problem. Discrepancies can be found in a previous article written titled “ABO discrepancies”. One such test is called the anti-A1 lectin test. 1-8% of A2 individuals will develop anti-A1, although not clinically significant, it can cause discrepancies. Lectin is a plant seed extract that agglutinates specific human cells. It agglutinates to A1 cells, but not A2 cells. Its possible to use this test to help resolve discrepancies.

Stay tuned for the next blood group system discussed.

-Caleb