Transfusion Medicine LOs Flashcards
What are the antigens associated with the Kell system?
What genotype is most common?
K = Kell k = Cellano
91% of people are kk
What processes can occur if alloantibodies are developed against K? What are the antibodies?
IgG antibodies at 37C may cause HDN and hemolytic transfusion reactions.
“Kell kills”
What is meant by the McLeod phenotype?
What system is it part of?
- Chronic compensated hemolytic anemia: “acanthocytes” (spur cells) on smears.
- Chronic granulomatous disease (CGD): no Kx antigen on neutrophils or monocytes - deficiency of NADPH-oxidase, thus no ability to kill microbes with it.
Kell system
What antibodies are found in the Kidd system?
Anti-Jka and anti-Jkb
What process may ensue in the Kidd system?
The antibodies are in low tiger and disappear quickly, so when the patient is transfused in the future, no antibodies will be detected in serum. However, upon transfusion, 3/4 will have a delayed hemolytic transfusion reaction; IgG activates complement.
The antibodies in which systems are noted to have a “dosage” phenomenon?
Kidd system + MNS system
What antibodies may exist in the Duffy system?
Fya and Fyb.
What phenotype, and in which system, allows AA patients to have resistance to malaria?
Fy (a-,b-) in the Duffy system
What processes may ensue if antibodies are developed in the Duffy system?
IgG antibodies may cause HDN and hemolytic transfusion reactions.
“Duffy dies”
Which systems tend to develop IgM antibodies?
MNS system and Lewis system
What are the antigens and antibodies seen in the MNS system?
Antigens: M + N, S +s.
Antibodies: anti-M is most common (IgM antibody), usually non-hemolytic.
What is meant by the dosage effect seen in the MNS system?
Antibodies react stronger with homozygous cells than with heterozygous cells.
What antibodies exist in the Lewis system?
IgM “warm” antibodies
Which system has antibodies that are found in secretions and plasma, then adsorbed onto RBC membranes?
What 2 things are required to develop these antibodies?
The reaction in this system is considered to be…
Lewis system.
A secretor and Hh gene.
Mild and not overly concerning.
What must be labeled on each specimen?
Time, date, initial of phlebotomist with a permanent ID of the patient.
What is type and screen vs. crossmatch?
Type and screen: only ABO, Rh and Ab screening (no crossmatch).
Crossmatch: testing of patient’s serum compatibility with donor cells.
What is the IAT?
Detection of Ig in patient serum against antigen on donor RBCs. Antibody must not be bound to RBCs to be detected.
Self serum vs. foreign cells.
What is the direct Coombs test?
Detects antibodies or complement proteins attached to RBCs.
Patient’s RBCs vs. donor serum.
Which antibodies are found at the following temperatures in the IAT?
Room temperature
37C
AHG
Room temperature: “cold” antibodies; IgM. Not usually clinically significant.
37C: detection of “warm” antibodies; IgM-IgG mixtures. Detection of Rh, Kell, Kidd and Duffy systems.
AHG: detection of “warm” antibodies; IgG that coat the RBC membrane.
What lab findings are seen in AIHA?
What signs suggest intravascular hemolysis?
How is AIHA confirmed?
+/- anemia, increased reticulocytes, increased UBR, decreased haptoglobin.
Hemoglobinuria and hemoglobinemia.
DAT (Coombs) and characterization of autoantibodies as cold or warm.
What is the most common autoantibody?
What type of antibody is it?
Benign cold agglutination (4C).
IgM.
AIHA is commonly associated with warm or cold reactions?
What positive test in AIHA is characteristic?
What is the treatment?
70% warm and 16% cold.
+ DAT: IgG
Many patients will not need a transfusion - steroids and splenectomy may be indicated.
What is associated with cold agglutination disease?
What is a unique feature of it?
Mycoplasma infections, pneumonia or mononucleosis causing intravascular hemolysis.
Hemolysis increases as patient is exposed to cold and complement is activated - avoid cold weather!
How long should patients be monitored when receiving a transfusion?
What actions should be taken if a reaction is noticed?
15 min.
**stop transfusion!
Report reaction to blood bank immediately.
Send post-transfusion blood sample.
What are the symptoms of acute hemolytic reactions?
Hypotension
Hemoglobinuria
DIC
Flank pain
What are the symptoms of febrile non-hemolytic reactions?
Fever
Chills
HTN*
What is the cardinal feature of TRALI?
Non-cardiogenic pulmonary edema - resembles ARDS
What blood product most often causes sepsis?
Platelets
What is the pathogenesis of acute hemolytic reactions (AHTRs)?
What does mortality depend on?
What is the treatment?
Pre-existing natural IgM antibodies induce complement-mediated intravascular hemolysis.
+DAT
The amount of RBCs transfused.
If mild, only observation.
If severe, cardiovascular support, fluids, etc.
Improper identification of patients is the most common cause of…
Acute hemolytic transfusion reactions (AHTRs)
When does delayed hemolytic reactions (DHTRs) occur?
What is the pathogenesis?
In some patients, this may precipitate…
What is the treatment? What is the best prevention?
> 24 hrs, but < 2 wks.
*Extravascular hemolysis due to IgG from prior transfusions/exposures.
+DAT.
Sickle cell crisis.
Most often patients do OK and don’t need much treatment, but if necessary, treat with fluid loading and dieresis.
The best prevention is serologic detection of RBC antibodies prior to transfusion.
What is the definition of a febrile non-hemolytic reaction?
What symptoms may be seen?
What is the severity?
A rise in temperature of 1C or more post-transfusion.
Fever, +/- chills, rigors, HA, N/V, etc.
It is not life threatening, but is important to exclude other possible causes.
What is used in treatment and prevention of non-hemolytic febrile transfusion reactions?
What should absolutely NOT be used?
+/- antipyretics; often the fever subsides on its own.
To prevent, premeditating with antipyretics is useful.
Do not use ASA, as it effects platelets!
What is associated with a febrile non-hemolytic transfusion reaction?
How can it be prevented?
Acquired antibodies to leukocytes in transfused products. This is attributed to pyrogens cytokines in units during storage.
Reduce WBC concentration of units, plasma reduction or PC wash.
What 2 unique findings are seen in allergic (urticarial) transfusion reactions (aside from the common allergic symptoms)?
Laryngeal edema: hoarseness, strider, “lump” in throat.
Bronchoconstriction: wheezing, chest tightness, DOE, etc.
If a patient with an allergic transfusion reaction demonstrates dyspnea, what should be ruled-out?
TRALI and volume overload
What is the treatment of severe allergic transfusion reactions?
How is it prevented in patients with IgA deficiency?
Epinephrine, diphenhydramine and aminophylline.
Give IgA. Products, or washed PC.
May premedicate with antihistamines or steroids.
What do antibodies bind in TRALI?
What is a unique PE finding that is characteristic?
There is no sign of…
When does it most often resolve?
MHC class I antigens, mostly on neutrophils.
No abnormal breath sounds, yet the CXR shows pulmonary edema.
No signs of cardiac involvement!
2-4 days post-onset.
What is the treatment of TRALI?
Aside from the presence of antibodies in donor serum against MHC, what else primes WBCs to cause leakage/injury?
Antipyretics and fluids.
Lipid inflammatory mediators.
Which 2 bugs tend to grow in PC? Why?
Which 5 bugs can grow in platelets?
Yersinia enterocolitica and Pseudomonas, because they can grow at low temperature and high-iron environments.
Staph, Strep, Salmonella, E. Coli and Serratia.
What are some indications for RBC transfusion? (3)
Hb < 7 g/dL or Hct < 21% in otherwise healthy person with acute anemia.
Hb 7-9 g/dL in a patient with CV or cerebrovascular risk factors.
HbS 30-50% in sickle cell patients.
What is the major indication for PRBCs?
What are some contraindications? (3)
Symptomatic anemia - increased loss, decreased survival or production of RBCs.
Volume expansion, coagulation deficiency or drug-treatable anemia.
What is the indication for platelet transfusion?
What is the threshold for transfusion?
What are some contraindications? (2)
Patients with Rh exposure from RBC contamination may require…
Bleeding due to thrombocytopenia or prophylaxis in severe cases.
Absence of bleeding < 10K platelets.
- significant hemorrhage < 50K
- risk of CNS bleed < 100K
Plasma coagulation deficit, clinical conditions associated with rapid platelet destruction (ITP or TTP).
Rh IG (RHIG)
What is the benefit of irradiated platelets?
Gamma irradiation inactivated donor lymphocytes and reduces risk of GVHD.
What does reduced exposure to single platelet donors cause?
Increased platelet retention.
What is the indication for FFP? (2)
What is the threshold?
What is the contraindication?
1 unit should increase factor level how much?
Deficiency of coagulation factors or without bleeding.
- emergent reversal of warfarin.
- treatment for TTP.
Prophylaxis - PT or PTT and active bleeding risk.
Documented factor deficiency in bleeding patient.
Volume expansion.
1 unit increases factor level 20-30%.
What is contained in cryoprecipitate?
What is it used for? (2)
What lab value is the threshold for transfusion?
Fibrinogen
Factor VIII deficiency (hemophilia A) or vWF replacement.
Fibrinogen < 80 mg/dL.
What is the Kleihauer-Bette test?
It measures fetal Hb in mom’ circulation.
What are the 3 indications of RhoGAM?
Rh- mom with an Rh+ baby.
Transfusion of Rh+ blood to Rh- patient.
Treatment of ITP.
Infusion must be completed in how much time?
What kind of saline must be used?
Within 4 hrs and unused blood must be returned within 30 min.
Only normal saline!
What is the use of solvent detergent treated plasma (SDTP)?
It inactivated enveloped viruses (HIV and HBV).
What is the major concern when transfusing granulocytes?
Allergic and febrile reactions (i.e. GVHD)!
“Massive transfusion” =
3 associated problems:
What is the “rule of thumb”?
Transfusion that amounts to full blood volume over 24 hours (usually 10-12 units daily in adults).
Coagulopathies
Hypothermia
Hypocalcemia
Give 1 unit of FFP per every 2-3 units of RBCs.
