Platelet Transfusion (BSH 2016)

Intro

 

Usage

  • 275,000 adult platelet units used per year in England

  • Increasing demand, 25% over 7-8 years. Due to ageing population and increasing survival and treatment intensity of haematological malignancy

  • Users

    • Haematology 70%, Cardiac surgery 10%, ITU 10%

Donors

  • Number of donors down 35% compared to year 2000

Dosage

  • Approx 240 x109 platelets contained in 150-300ml plasma/PAS

 

WHO Bleeding Score (summarized)

 

0 – No bleeding

1 – Petechiae in dependent sites, oropharyngeal bleeding, epistaxis <30 min

2 – Mild GI bleeding, epistaxis >30 min, multiple bruising, bleeding in cavity fluids

3 – Bleeding requiring RBC transfusion, Neuro bleed on CT without symptoms

4 – Debilitating bleeding, haemodynamic instability from bleeding, fatal bleed

 

Principles

 

Identify cause of thrombocytopenia first so as to treat correctly

Use other measures first

  • Local measures (compression), use of lowest risk procedure / equipment

  • TXA

  • Think about desmopressin, fibrinogen, TPO’s

 

Contraindications to plt transfusion

 

Thrombotic microangiopathies

 

Risks

 

 

Allergic Reaction (1 in 6000)

  • Patients with history of >mild allergic reaction to platelets should receive platelets suspended in PAS. If continues to react, use washed platelets.

ABO and Rh Incompatibility (1 in 600,000)

  • Acceptable to use ABO incompatible platelets to reduce wastage, but these should be high titre negative units. Use pf Platelet Additive Solution (PAS)  for pooled platelets reduces risk further

  • Rh D- girls and women of childbearing potential should receive Rh D- platelets. In emergency, give Anti-D 250 IU to cover Rh D+ platelets

  • Rh D- boys <18 yo, those with anti-D antibodies and transfusion-dependent adults should ideally receive Rh D- platelets, but not at the expense of Rh D+ wastage. Anti-D not required

TRALI (<1 in 1 million)

  • Reaction between donor leukocyte antibodies and recipients leukocyte antigens

Transfusion-Transmitted Infection (TTI)

  • HIV 1 in 7 million, Hep B 1 in 1 million, Hep C 1 in 30 million

  • Bacterial contamination, rare since bacterial screening started in 2010

Post-transfusion Pupura

  • Almost exclusively occurs in women following transfusion of platelet containing blood products (RBC, Plt, Granulocytes) leading to alloimmunisation against an antigen of the donor cells but that then causes destruction of patient’s own platelets.

  • Typically 5 days post-transfusion. Lasts days to weeks. Rx with IVIg

All clinical areas transfusing platelets should be able to deal with acute transfusion reactions and have guidelines for such events in place.

 

Platelet Refractoriness

 

A one hour post transfusion increment of <5 on two separate occasions when using ABO-identical platelets and in the absence of non-immune factors.

Non-immune causes are more common than immune

  • Consumptive coagulopathy, sepsis & splenomegaly account for 80% of cases

 

Management Pathway

  1. Use ABO matched platelets

  2. Patients refractory to platelets for non-immune reasons, HLA matching not indicated

  3. Class 1 HLA-matched platelets

  4. HPA matched platelets

 

Specific Cases

 

Glazmann thrombasthenia

  • Lack of 2b/3a receptor increases the risk of alloimmunisation

  • Consider fFVIIa first line. HLA-matched if plt used.

Other congenital platelet disorders – consider TXA + Desmopressin first line.

 

ITP

  • Only consider if treatment has failed and urgent intervention required.

  • Give in combination with IVIg

 

Acquired platelet disorders (i.e. Anti-platelets)

  • In vitro studies suggest aspirin more reversible than clopidogrel/ticagrelor

  • However, aspirin increases bleeding risk but not severity and so platelet transfusion rarely indicated

  • Odds of death or disability higher for platelet transfused patients in a RTC looking at ICH on anti-platelets. ?Due to being on aspirin for an underlying thrombotic condition. However overall was not a good quality trial

  • Do not use platelets when antiplatelet agents have not been stopped

  • Use general measures +/- TXA

  • Consider plt transfusion if critical bleeding not responding to other measures

  • Consider plt transfusion in bleeding with plt count <10 due to abciximab

 

Platelet transfusion thresholds

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