Blood products incl. special prep Flashcards
What is the “storage lesion” physiologically driven by?
Membrane changes (eg. microvesiculation), increases in free potassium, hemoglobin, and lysophospholipids, and decrease in pH, ATP, and 2-3-DPG.
What is the requirement for red cell yield after storage?
75% of the cells must survive in circulation 24hrs after transfusion. Less than 1% hemolysis is permitted.
Do platelets suffer from storage lesion?
Yes, they metabolize sugars and fatty acids to generate carbonic acid.
What are the indications for blood product irradiation?
Hematopoietic stem cell transplant
Directed donation
Intrauterine transfusion
Generally, impaired cellular immunity.
What is the required dose of irradiation for irradiated products?
25Gy to center of bag
15Gy to rest of bag
What are the requirements for leukoreduction?
3-log reduction in leukocytes (>99.9%)
For RBCs and pheresis platelets, no more than 5 x 10*^6 leukocytes.
For WB-derived platelets, no more than 8.3 x 10^5 leukocytes.
Can platelets be volume reduced?
Yes, but they should be allowed to sit 20-60min before re-agitation or dispensation.
What are the indications for washing of blood products?
Deglycerolization
Selective plasma protein deficiencies (IgA, Haptoglobin)
HPA-1a antibodies or post-transfusion purpura
IUT
How much cell loss is permitted with washing?
20% loss of red cell yield
33% loss of platelet yield
How should whole blood be reconstituted?
Use group O RBCs and group AB plasma and aim for a hematocrit of about 50%.
What is aliquoting? What are its indications?
Splitting into low-volume containers. For pediatric transfusions (reduces number of donor exposures) or for very slow infusions (which must complete in 4hrs)
What percentage of D-negative patients alloimmunize after receiving D-positive RBCs? Platelets?
22% immunize after RBCs.
2% immunize after platelets.
May be able to reduce with RhIG
What rate of transfusion defines massive tranfusion?
8+ RBCs in 24hrs, or 4+ RBCs in 1hr.
After a patient receives emergency-release blood products, how should the presence of anti-A or anti-B be treated?
Respect it, even if it is passively acquired. You may have to continue to only give group O RBCs.
What is the crossmatch to transfusion ratio?
The number of units that gets crossmatched for surgery relative to the number actually transfused. A high ratio indicates units being needlessly held up in crossmatch.
What are the benefits of pre-storage leukoreduction?
Leukoreduction reduces FNHTRs, alloimmunization, and CMV transmission.
What are the requirements for leukoreduction to be effective?
3-log reduction in leukocytes (<99.9%), down to <5 x 10^6 leukocytes per unit (sixth that for acrodose platelet)
What is in cryoprecipitated AHF?
Fibrinogen, factor VIII, vWF, fibronectin, and factor XIII.
What is the recommended number of granulocytes per transfusion?
4 x 10^10
How many units are in a pool of cryoprecipitate
Formerly 10, now 5
From what products can cryoprecipitate be made?
FFP, PF24, or PF24RT24
What are the minimum and expected amounts of fibrinogen and factor VIII in a unit of cryo?
Fibrinogen: 150mg minimum. 250mg expected.
fVIII: 80 IU
What are the indications for cryoprecipitate?
Correction of hypofibrinogenemia (liver dz, obstetrical hemorrhage, trauma/DIC), uremic coagulopathy, and rarely correction of fXIII deficiency.
What are the risks associated with cryo transfusion?
Infectious disease risk
Prothrombotic complications (due to fXIII, vWF)
TRXNs as seen in plasma-rich products.
How is cryoprecipitate dosed for fibrinogen?
Multiply delta fibrinogen level (mg/dL) by patient blood volume (in dL). Divide by fibrinogen per dose (250mg/unit, or 1250mg/pool)
How is cryoprecipitate dosed for factor VIII?
Multiple delta activity by 40 and patient bodyweight in kg. Divide by fVIII per unit (80).
What alternatives exist for cryoprecipitate?
RiaStap (plasma-derived fibrinogen concentrate)
Recombinant factor VIII (many products)
Corifact (plasma-derived fXIII)
VonVendi (recombinant vWF)
Whose blood cannot be leukoreduced?
Sickle trait paitents (clogs filters).
How much RBC mass should survive leukoreduction?
At least 85%
What radioisotopes are used for irradiation?
Cesium 137
Cobalt 60
What is the downside of irradiation?
Cost, hyperkalemia (only a concern in small children)
How should units be handled in quarantine?
They must be kept physically separate from transfusible product, ideally in another fridge. OK to work on splitting and processing while in quarantine.
What must be on every blood product label?
ISBT 128 code
Barcode: Facility ID, donor lot, product code
ABO/Rh of donor
Any additional labels indicating special processing or tie tags
What is the purpose of the acid in ACD?
Stops dextrose from caramelizing during sterilization
What are the primary benefits of whole blood over components?
Less AC, faster transfusion, easier logistics
What is a typical yield loss in deglycerolization?
10-20%
What is the difference between PF24 and PF24RT24?
PF24 should be refrigerated within 8 hours. RT can be held at room temperature. Both have less V, VIII, and probably C and S.
What is the expiry time of liquid plasma?
26 days
What are some accepted methods of plasma pathogen reduction?
Heating
Methylene blue + UV
Solvents/Detergents (eg. Octaplas)
INTERCEPT, Mirasol…
If a platelet unit is visibly red, what red cell content is present?
At least 0.5% by volume.
What is the “platelet swirl”?
A visible phenomenon caused by tight platelet clumping, indicating platelet death usually by acid or bacteria.
What is a typical factor VIII level in a cryo unit, and what factors can influence this?
Average ~150U. Group O donors have less (due to increased vWF clearance)
What is a recommended granulocyte dose by weight? how much is in a granulocyte unit?
Recommend 0.6 x 10^9/kg, but the average unit only has 4 x 10^10 (only satisfies up to 67kg recipient)
Why might a blood transfusion service (not a donor/manufacturing service) require an FDA license?
Any product modifications including pooling and irradiation requires re-labeling of the new product.
Why may blood for neonatal purposes ideally not contain adsol?
Adenine and mannitol may be nephrotoxic to infants.
What volume should be used in washing? How can the product quality be checked?
1-2L NS.
Check last wash for Hb content; should have < 300mg
How can platelets be extended to 7d expiry?
Verax testing (PDG test) Delayed/subsequent sampling
What is in platelet additive solution?
Acetate (“fuel” for platelet metabolism; doesn’t generate lactate), potassium, magnesium, phosphate
How is liquid plasma made?
It is only derived from whole blood, never apheresis. It is never frozen. It should always be irradiated.
How does pathogen reduction with methylene blue affect the factor levels in plasma rich products?
Reduces fibrinogen and factor VIII.
When should platelets be rested?
After hard-spin, washing, INTERCEPT illumination…
How long are platelets stored in syringes fully functional?
At least 6 hours.
