Transfusion Medicine

Question 1

Packed RBCs

Answer 1

About 250ml. volume at 75-80% Hct.
Kept refrigerated, shelf life is 42 days
Glucose, citrate, and electrolytes are added to the bag to keep RBCs alive and metabolically active and have a life of 42 days

Indications:
Symptomatic anemia.
Anemia with ischemic heart disease.
Exchange transfusion - pediatrics and adults with conditions in which plasma have autoantibodies; take a unit and put one in until blood diluted enough of the autoAb

In adults, each transfused PRBC should raise [Hb] about 1 gm./dL.

Question 2

Indications for Platelet Transfusions

Answer 2

Thrombocytopenia due to decreased production in a bleeding patient.

Thrombocytopenia without bleeding preoperatively.

Qualitative platelet defect with bleeding.

Typical dose – 1 platelet pheresis pack. Expected increase in plt. count is 30,000/uL. or more

Question 3

Single Donors Plasma

Answer 3

Contains humoral clotting factors.
Frozen within 24 hr. of collection.
Transfused to ABO-compatible donors.
Fresh frozen plasma not generally available any longer

Indications:
Bleeding due to a decrease in multiple humoral coagulation factors (PT or PTT prolonged).
Emergency treatment of patients with single factor deficiencies when recombinant products are not available

Question 4

Screening of Blood

Answer 4

History to exclude donors that have an infectious disease at time of donation.
Limited physical – temp.
HIV 1 and 2 Ab, HIV NAT
HCV Ab,  HCV NAT
HbsAg, AntiHBc, HBV NAT
HTLV I&II Ab
West Nile Virus NAT (seasonal)
VDRL
ABO &Rh type, Antibody screen
Hep B and C

Question 5

Acute Hemolytic Transfusion Reaction

Answer 5

ABO incompatibility – A or B Ag on donated cells binds to anti-A or anti-B in recipient plasma – rapid intravascular hemolysis with activation of C5-9 MAC attack.
Incompatibility usually due to a clerical error; specimens or patients mixed up.
Back pain, fever, oliguria, hematuria, hypotension, DIC

Intravascular hemolysis – free plasma Hb and hemoglobinuria

Question 6

Delayed Hemolytic Transfusion Reaction

Answer 6

Previous exposure to RBC Ag sensitizes patient to that Ag.
Ab titer becomes low months/years after sensitization; Ab screen is negative.
Anamnestic response follows re-exposure; blood lysed 2-3 days after transfusion

Patient builds up Ab so hemolysis occurs after a day or two after
Hb should increase from transfusion, but if decreases can be having a delayed hemolytic reaction

Question 7

Febrile Transfusion Reaction

Answer 7

Fever caused by donor WBC HLA Ag.
Dx: temp. increase during transfusion of 2 degrees Fahrenheit; rule out other causes of fever.
Can be prophylaxed with acetaminophen.
Less common with use of leucocyte reduced products – helps reaction almost go away
Mediated by WBC HLA Ag in the donor unit and triggers release of cytokines that induces fever

Question 8

Allergic Reaction

Answer 8

Due to reaction with plasma proteins in donor unit.
Reaction ranges from hives(urticaria) to anaphylaxis. Most severe reactions are due to IgE specific for IgA in IgA-deficient recipients.
Can be prophylaxed with antihistamines prior to transfusion
Rash of gives mediated by plasma proteins in the donor unit (NOT HLA)
Vasodilation occurs

Question 9

Graft vs. Host Disease

Answer 9

Donor T-lymphocytes recognize recipient as foreign; release cytokines and chemokines that mediate recipient cell death.
Rare in immunocompetent recipients but has been reported; more common in immunocompromised recipients.
Prophylaxis – radiate donor products to kill lymphocytes

Question 10

Volume Overload

Answer 10

Infused normal saline and RBC may overwhelm recipient’s ability to excrete sodium and water; leads to heart failure and pulmonary edema.
More common in elderly patients with limited cardiac reserve.
Can be mitigated by use of diuretics prior to and following transfusion

Question 11

Transfusion Related Acute Lung Injury (TRALI)

Answer 11

First recognized in 1992. A leading cause of transfusion related death.
Mediated by HLA Ab in donor plasma – more commonly found in female donors.
Pulmonary damage within 6 hr. of transfusion; pulmonary edema, ARDS.
Prevention: all male plasma products, look back program for all TRALI cases
Blood or platelets, the HLA interact with neutrophils in lungs, then degranulate and increase permeability in lungs and get edema

Question 12

Bacterial Contamination

Answer 12

Most often in platelets; can occur in any product.
Contamination can occur at time of collection or after collection via cracked or defective plastic bags.
Rapid increase in recipient temperature, chills, hypotension, death can occur.
Prevention – platelet pH is checked before shipment from supplier; rejected if too low