• Platelets are small, disc shaped cells that have a critical role in helping our blood clot and stop bleeding. When there is a break in the vascular endothelium, a process of platelet activation occurs and the platelets change shape and aggregate to form a platelet plug.  
  
• Platelets are commonly transfused to patients with low platelet counts or patients with platelet dysfunction who are bleeding or at high risk of bleeding.
  
• All platelet components are leucodepleted and irradiated prior to release from Lifeblood.  
  

Indications 

RCH - Platelet transfusion indications poster for download. 

Dose, characteristics of platelet products, administration, compatibility and storage 

Platelet dose, administration, compatibility and storage poster for download. 

Dose

Platelet product                                                                  Dose if < 15 kg            Dose if > 15 kg

Pooled or apheresis platelets (including pedipaks)                    10 mL/kg                  One adult unit 

Types of products available:

Apheresis platelets

Dose of platelets obtained from a single donor and suspended in a mixture of Platelet Additive Solution (PAS) and approximately 40% donor plasma. Apheresis platelets can be used to decrease donor exposure in chronically transfused patients. In patients who rely on platelet support e.g. severe aplastic anaemia, they may be selected when available to reduce the risk of alloimmunisation. 

Characteristics:

• Volume (mL)                              216 ± 9    (100 mL – 400 mL) 
• Platelet count (10⁹/unit)             287 ± 35

Paediatric apheresis platelets (pedipaks)

One unit of apheresis platelets may be divided into three equal packs to create paediatric sized components (pedipaks). This will enable smaller patients requiring small but regular top ups to have exposure to less donor products and minimise product wastage. 

Characteristics:

• Volume (mL)                              55 ± 2    (40 mL – 60mL) 
• Platelet count (10⁹/unit)             71 ±9 (>50)

Pooled platelets in PAS

An adult dose of pooled platelets are obtained from a pool of buffy coats from four donors. These are pooled and re-suspended in PAS to create one unit of pooled platelets.

Certain patient groups may require pooled platelets as the first choice. The ratio of plasma to platelets is less in pooled components than apheresis products and therefore the exposure to plasma is less. This becomes significant for those patient groups who have mild – moderate allergic reaction to apheresis platelets. 

Characteristics:

• Volume (mL)                              270± 12 (>160) 
• Platelet count (10⁹/unit)             264 ± 37

Platelet administration

• The patient should be ready for transfusion prior to picking up platelets from the blood bank. e.g. appropriate IV access and medical order for transfusion.
• Patient identification is required for all blood products to be issued from blood bank
• Complete positive patient and blood product identification prior to transfusion of platelets as per RCH Blood Transfusion - Fresh Blood Products Procedure.
• Care and monitoring of transfused patients, refer to Blood Administration
• Administer via a volumetric pump or syringe driver to ensure accurate volume delivered.
• Standard 170–200-micron filter either in-line or on transfer to syringe.
• Use a new blood administration filter (170 - 200 micron) when administering platelets.
• Do not transfuse though the same blood administration filter after red blood cell transfusion as some platelets may get caught in fibrin strands/debris caught in filter. 

Compatibility

• The provision of ABO and Rh(D) identical platelet transfusion is ideal, but not always possible. If ABO compatible components are unavailable, patient age, weight, diagnosis and component availability (pooled vs apheresis) will influence the blood bank decision about what product to supply.
• An ABO incompatible platelet transfusion (group O platelets given to a group A patient) may be associated with clinically significant transfusion reactions, including a positive DAT, red cell haemolysis and even lower platelet survival in some patients. 
• Platelet components contain a small number of red cells that could be Rh incompatible with the recipient. Therefore, RhD negative females with childbearing potential should receive platelet transfusions from RhD negative donors. If transfusion of RhD positive product to RhD negative recipient is unavoidable, consider giving Rhesus immunoglobulin (Discuss with haematologist-on-call)

Special platelet transfusions

Platelet Transfusion in patients undergoing stem cell transplantation

• Where possible, a platelet product compatible with both donor and recipient should be used. At RCH the platelet product choice for each transplant recipient will be specified by their transplant physician and will be listed on the Transplant Protocol

Platelet transfusion in children with congenital platelet disorders

• Platelet transfusion in rare congenital platelet disorders such as Bernard-Soulier syndrome, Glanzmann's thrombasthenia, thrombocytopenia with absent radii (TAR), Wiskott-Aldrich syndrome, Fanconi anaemia, amegakaryocytic thrombocytopenia can provoke the development of multi-specific HLA or platelet specific antibodies and they should be used sparingly. They should be reserved for clinical bleeding or prior to invasive procedures with a high risk of bleeding.
  
• Donor exposure should be limited through the use of apheresis platelets and the risk of alloimmunisation reduced through the use of leukocyte reduced products.

Platelet transfusion in immune thrombocytopenia

• Transfused platelets are rapidly destroyed and should be reserved for cases of life-threatening bleeding. 

Special Products

Phenotype specific for patients with fetomaternal alloimmunisation (FMAIT)

• The infant or fetus with confirmed or suspected alloimmune thrombocytopenia should be transfused platelets which are negative for the implicated alloantigen. Platelets negative for the HPA-1a antigen (implicated in 85% of cases of FMAIT in Caucasian populations) are often available from ARCBS but may be sourced from interstate. Contact the haematologist on-call for advice regarding platelet support in this clinical situation.

HLA matched for immunised refractory patients:

• When patients fail to achieve a significant and sustained rise in the platelet count following platelet transfusion (platelet increment) they are said to be 'refractory'. There are clinical and immunological causes of platelet refractoriness. Clinical causes include fever, sepsis, bleeding, DIC and some drugs. In these situations, patients may respond to more frequent platelet transfusions or higher doses of platelets. Patients undergoing stem cell transplantation, who are multiply transfused, or who have had prior pregnancy may become refractory to platelet transfusion due to the development of multispecific HLA or platelet-specific antibodies. These patients may require platelet support from HLA (Human Leucocyte Antigen) or HPA (Human Platelet Antigen) matched donors. 
  
• If HLA or HPA matched apheresis platelets are required, please contact the haematologist on-call for advice and RCH Blood Bank, ph 55829.

IgA deficient:

• IgA deficient components may be used in patients who have developed an anti-IgA antibody and who also have recurrent, severe allergic reactions. The FFP is obtained from donors who have known low titre IgA/IgA deficiency. 

Adverse effects of platelet transfusion

• See section on adverse effects of transfusion.
• Platelet products are collected from volunteer donors screened with standard screening tests and have the same risks of infectious disease transmission as red cell products.