Basics of Transfusion Therapy

Platelet Refractoriness Laura Cooling MD, MS Associate Medical Director Transfusion Medicine

Platelet Kinetics circulating life span 8-10 days

Circulation 60%

Spleen 30-40%

10-12% loss/day 20% endothelial integrity 80% senescence

Definitions of Refractoriness

2-3 consecutive platelet transfusions by CCI or PPR

REFRACTORINESS

ALLOIMMUNIZATION

Platelet Refractoriness Poor response to platelet by immune or nonimmune factors

Immune (25-50%) Alloimmunization Autoantibodies Passive Immunity Drug-related

Nonimmune (50-75%) Fever Infection Splenomegaly Drugs/Antibiotics Consumption Bleeding Platelet Dose

Effect of Platelet Count, Splenomegaly and “Refractoriness” on Platelet Survival 75%

Normal Plt>200K

65% 50%

Refractory

Normal Plt 7.5 Good Response * Platelet count at 1 hour post transfusion,

BSA=body surface area in M 2

Example: Patient (1.7 M 2) transfused with 5 units pooled platelets for platelet count=2. At 1 hr, plts=30K. CCI=(30-2)(1.7)/3.5=13.6

Specialty Products Documented Refractory Patients Pathology consultation and approval • Crossmatched Platelets (First Choice) – Single donor apheresis platelets “crossmatched” solid-phase technique with patient’s serum

• HLA Platelets – require HLA antibody screen + HLA type – Antigen negative: lack specific HLA antigens – HLA-matched: A or B matches only, require 810 days from Los Angeles Red Cross

Influence of Patient Factors and Storage Time on Platelet Transfusion Response* *Slichter 1997, adapted from Norol 1994 50 45 40 35 30 25 20 15 10 5 0

NS 30% (20 hr) Refractoriness = PPR < 30% (1 hr) or < 20% (20 hr)