Refractory Platelet Transfusion - Failure to achieve acceptable ↑ platelet count following transfusion. Normal t1/2 of 3 days.

Causes:

 • Alloimmune: Ab to class-I HLA antigens (e.g. +PRA) or PLT-specific antigens. Risk factors: multiple pregnancies, prior transfusions with non-leukoreduced blood products, and organ transplants.

 • Non-alloimmune: 2/3 of cases; Ddx: sepsis/DIC, HIT, TTP, CVVH/CPB/IABP, splenomegaly, HSCT, viral infection (HIV/HCV) and medications (sulfa, vanc, linezolid, piperacillin, rifampin, amphotericin, heparin, thiazide, anti-GpIIb/IIIa)

Evaluation: check plt 30min post-transfusion on 2 occasions and assess plt recovery (15min-1hr later) & plt survival (18-24hr later)

 • ↓ plt recovery (↑ <10k on 2 occasions) → alloimmune refractoriness

 • Normal plt recovery but ↓ survival → non-alloimmune refractoriness

Alloimmune refractoriness workup:

 • Consult Blood Transfusion Service p21829. Studies will not be processed without discussing w/ them first.

 • Send Panel Reactive Antibody: test for alloreactivity against HLA antigens. Normal is 0%, range 0-100%. If platelets required urgently (i.e. actively bleeding), notify Blood Bank and ask for send out to Red Cross

Management: With each platelet transfusion, must check a post-transfusion CBC within 15-60 minutes of completion.

 • ABO/HLA-matched apheresis single-donor plts from Red Cross. Takes days to process. Each unit costs approximately $3000 and has a shelf life ~3 days.

 • Consider aminocaproic acid if bleeding (contraindicated in thrombotic DIC); correct coagulopathy with DDAVP if e/o uremia



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