Apheresis - Leukapheresis/Plateletpheresis

Question 1

What are the symptomatic manifestations of leukostasis?

Answer 1

Cerebral: Headache, vision disturbances, delirium, somnolence
Pulmonary: Hypoxia, tachypnea, infiltrates on radiology

Question 2

At what counts/levels does leukostasis manifest?

Answer 2

Depends on nature of leukocytes; monocyte/monoblasts can manifest at 50k. Myeloid (as in AML) at 100k. Lymphocytes/lymphoblasts at 300-400k.

Question 3

What leukemia should never be apheresed?

Answer 3

APL (associated with worsening of coagulopathy)

Question 4

What parameters should be used in leukopheresis?

Answer 4

Aim to exchange 1.5-2x TBV (8-10L).

Question 5

How good is white cell yield in leukopheresis and how can it be improved?

Answer 5

With 1 TPV, 15-45% reduction. with 2, 50-85% reduction (leukocytes get released from spleen, etc, worsening yield). Hetastarch improves separation of myeloid cells from RBCs.

Question 6

What is selective leukocyte reduction? What systems exist?

Answer 6

Removal of activated leukocytes for treatment of autoimmune disorders (with unknown mechanism of action). Leukocyte adsorptive apheresis system (LCAP) and gran/mono apheresis system (GMA).

Question 7

Compare and contrast primary and secondary thrombocytoses with respect to the role of plateletpheresis.

Answer 7

Secondary thrombocytoses are rarely significant or dangerous enough to mandate apheresis. Primary more often is associated with thrombotic or bleeding abnormality and benefits from plateletpheresis.

Question 8

How does pregnancy affect risk of thromboses in primary thrombocythemia?

Answer 8

There is an increase of fetal losses in the first trimester, despite a spontaneous nadir in counts during this time.

Question 9

Why are platelets more likely to activate in erythrocytosis or leukocytosis?

Answer 9

Higher red cell volume creates more shear forces in laminar flow at the platelet margin. Leukocytes have more activating adhesions. Both are predictors for abnormal thrombotic events.

Question 10

What parameters should be used in plateletpheresis?

Answer 10

Aim to exchange 1.5-2x TBV. Set WB:AC lower than normal (8-12) because of platelet clumping.

Question 11

Why are leukodepletions always less effective than calculated?

Answer 11

Re-equilibration of blood volume, de-margination/mobilization of WBCs

Question 12

At what platelet levels should plateletpheresis be considered?

Answer 12

> 1M/uL