Ch. 7 - Blood components (practices) Flashcards
What are the indications for red cell transfusion?
Generally, for patients with symptomatic deficiency in oxygen carrying capacity and/or inadequate circulating RBC mass.
Also, for prophylactic exchange in hemoglobinopathies and in neonates with HDFN.
In general, what are some transfusion thresholds for red cell units?
Transfuse for Hgb <7 and not for >10.
What were the findings of the TRICC trial?
Patients on a restrictive transfusion strategy (Hb 7 threshold) have similar outcomes to those on liberal transfusion strategy (Hb 10 threshold), with the exception of in ischemic heart disease.
In general, what is the expected impact of transfusion of one unit of RBCs in an adult?
Hgb should rise by 1g/dL, and Hct should rise by 3%.
What is the dosing of RBCs in children? What is the expeted effect?
10-15 mL/kg, which is expected to increase Hgb by 2-3 g/dL or Hct by 6%.
What measures may be taken if the presence of underlying alloantibodies cannot be determined?
Adsorption studies
Phenotyping
Genotyping
What is “emergency release” in the context of blood transfusion?
In these circumstances, an attending physician assumes responsibility for the emergent need for blood, under the assumption that the benefit of transfusion outweighs risk of incomplete serologic workup.
What is massive transfusion protocol (MTP)?
Release of blood components in a fixed regimen so as to reconstitute whole blood (eg. 1:1:1). These ratios should not be modified while the MTP is active.
What are some platelet transfusion triggers?
Any patient (prophylactic): <10k
Patients with coagulation disorders, anatomic lesions, or undergoing CVC placement: <20k
Patients iwth active bleeding, undergoing LP, or non-CNS surgery: <50k
Bleeding into confined spaces such as CNS, ophthalmic, pulmonary?: <100k
What are some conditions that can cause thrombocytopathy?
Inherited disorders: Bernard-Soulier, Glanzmann’s etc
Drug effect: Antiplatelet
Myelodysplastic syndrome
Surgical/cardiac bypass
What are some contraindications to platelet transfusion?
ITP
TTP
PTP
HIT
What is the expected impact of one pheresis platelet unit?
The platelet count is expected to increase by 30k-60k.
What is the advantage of single-donor platelet transfusion over “six-packs”?
Less alloimmunization risk (see: TRAP)
Less infectious risk
Less risk in special cases such as IgA deficiency or NAIT.
What is the role of ABO-matching in platelet tranfusion?
ABO-identical platelet units generally have better effect on raising platelet count, but incompatible transfusion is often acceptable. Consider volume reduction in sensitive cases (eg Pediatrics)
Describe the workup for platelet refractoriness.
- Rule out nonimmune causes (fever, sepsis, splenic sequestration, drugs, DIC/TTP)
- Perform corrected count increment (CCI) 1hr after transfusion.
- If refractory, perform HLA evaluations.
How is CCI calculated?
(Body surface area * [change in platelet count])/(number of platelets transfused)
What are the three treatment options for platelet refractory patients?
- HLA-matched platelets
- HLA-antigen negative units for patient’s known HLA antibodies
- Platelet crossmatch-compatible units
Describe the grading of HLA-matching in platelets.
Match HLA-A and HLA-B, as follows:
A: Four antigens matched
BU: Three antigens identical, one unknown
B2U: Two antigens identical, two unknown
B1X: Three antigens identical, one CREG
B2UX: Two antigens identical, one unknown, one CREG
C, D: Mismatched antigens
How should all HLA-matched platelets be treated?
All should be irradiated.
How is Rh matching handled in platelet transfusion?
Try to provide Rh-negative platelets to Rh-negative women of childbearing age. Otherwise, transfuse with RhIG.
How is platelet crossmatching performed?
Solid phase red cell adherence assay; mix recipient serum with donor platelets and indicator red cells.
Name 5 indications for plasma transfusion.
- Active bleeding with multifactor deficiency
- Emergency reversal of warfarin-induced coagulopathy (with bleeding)
- Use as replacement fluid for TPE
- Patients with congenital factor deficiencies
- Hereditary angioedema (C1 esterase deficiency) **outdated
What is the role of plasma in correcting INR abnormalities?
Mild abnormalities are not well-effected by plasma administration. INR moreover is a poor predictor of significant clinical bleeding.
What is the typical dose and expected effect of plasma transfusion?
10-20mL/kg
Should increase all coagulation factors by 20% (give quickly!)
Compare the utility of FFP, PF24, and PF24RT24.
All are clinically equivalent for treating multifactor deficiencies, but FFP should be used in patients with single factor deficiencies (eg fV deficiency)
What are some (current and former) indications for cryoprecipitate?
Fibrinogen deficiency (congenital or acquired) Treatment of bleeding in uremia von Willebrand disease (former) Hemophilia A (former) *also used as a topical fibrin sealant
How is cryo dosed, and what is the expected impact in adults?
A dose of cryo is typically 10 units, and is expected to raise fibrinogen level by around 100mg/dL.
How is cryo dosed in a pediatric population?
1-2 units per 10kg. Should still raise fibrinogen level by around 100mg/dL.
How can the number of cryo units be calculated given a desired fibrinogen level?
(Change in fibrinogen level * plasma volume)/ 250mg (per unit).
When should granulocytes be considered as a therapeutic option? 4 criteria.
- ANC < 500
- Bacterial or fungal infection for 24-48hrs
- No evidence of improvement with Abx
- Reasonable chance of future BM recovery
What is a standard dose of granulocytes? How should the unit be treated?
1.0 x 10^10 granulocytes. ABO and CMV-match the donor. Irradiate!
Compare and contrast albumin and plasma protein fractions.
Albumin: 96% albumin, 4% globulins. Prepared by cold alcohol fractionation and heat-inactivated.
Plasma protein fractions: 83% albumin, 17% globulins, less purified than albumin.
What are the indications for albumin?
Treatment of hypovolemia Acutely hypoproteinemic patients Burns Replacement fluid for plasmapheresis (not for nutritional correction!)
Describe the two preparations of factor VIII concentrate.
Plasma-derived: Made by fractionating pooled plasma. Has some vWF, okay for treatment of vWD.
Recombinant: High purity, okay for treatment of hemophilia A
What are the half-lives for concentrates of factors VIII, IX, X, and XIII? Fibrinogen?
VIII: 8-12hrs IX: 18-24hrs X: 30hrs XIII: 9d Fibrinogen: 3d
What is prothrombin complex concentrate (PCC)? aPCC?
A product of factor IX that also contains other vitK-dependent factors (II, X, and maybe VII). aPCC has activated factor VII. They can be used for severe bleeding and…various bleeding disorders.
What is topical fibrin sealant?
A product containing fibrinogen and thrombin in separate containers, which is mixed to form a fibrin clot.
What substances should never be infused with blood products?
Medications
Non-isotonic solutions (eg 5% dextrose)
Calcium-containing fluids (eg Lactated Ringer’s)
What rate of transfusion should be observed for blood products?
Start slow, usually 1-2mL/min to observe reactions.
Transfuse 2mL/min for granulocytes, 4mL/min for RBCs, and 5mL/min for plasma products.
In any case, finish within 4hrs.
In what contexts are blood warmers most useful?
During massive transfusion (trauma, surgery, apheresis), in newborns, and maybe in cold-agglutinin disease.
