Apheresis - Red cell exchange

Question 1

What is a shorthand measure to determine adult patient blood volume? Pediatric?

Answer 1

70ml/kg in men, 65ml/kg in women.

Children have higher; pre-emies may be as high as 100ml/kg.

Question 2

At what crit are most pRBCs stored?

Answer 2

60%; except for CPDA (80%)

Question 3

For what conditions should a red cell prime be used?

Answer 3

Extracorporal blood volume >15% of TBV
Intraoperative anemia (crit <20%)

Question 4

What is the average lifespan of sickle cell patients?

Answer 4

45yo

Question 5

What crises in SCD merit red cell exchange?

Answer 5

Severe ACS
CVA (including CRAO and prophylaxis)
Intrahepatic cholestasis (poorly described)
Recurrent priapism and other crises (weak)

Question 6

What is ASPEN syndrome?

Answer 6

A rare occurrence of neurologic complications following exchange for priapism.

Question 7

What is the rate of antibody formation in sickle cell disease?

Answer 7

8% form autoantibodies

36% form alloantibodies

Question 8

How does iron overload manifest in sickle cell disease?

Answer 8

Hepatic, cardiac, and cutaneous manifestations. May affect endocrine function (same as in hemochromatosis)

Question 9

What are the features of sickle cell hyperhemolysis?

Answer 9

Reticulocytopenia, drop of hemoglobin to below pre-transfusion levels. DAT may be positive or negative…

Question 10

How should stroke prophylaxis be done? Primary and secondary?

Answer 10

Target a HbS <30%. If done for primary prophylaxis, transfuse for MCA TCD 200cm/s.

Question 11

What antigens should be phenotyped for in sicklers?

Answer 11

ABO/RH
Kell
Duffy
Kidd
Lewis
MNS

Question 12

What are the goals of transfusion therapy in thalassemias?

Answer 12

Target a Hb of ~9.5 for normal growth? Goal is to reduce splenism and extramedullary hematopoiesis. Transfusion only needed in major or compound thalassemias.

Question 13

What are the exchange criteria for parasitemias?

Answer 13

For both malaria (mainly falciparum) and babesia: Exchange if >10% parasitemia (>10% of red cells parasitized).

Question 14

What are some non-hemoglobinopathic indications to perform red cell exchange?

Answer 14

Parasitemia
Incompatible ABO transfusion
Toxins (CO, methemoglobin, porphyrias? cyclosporine?)

Question 15

What is the risk of alloimmunization of a unit of exchanged red blood cells as compared to simple transfused?

Answer 15

Risk is lower.