PLATELET TRANSFUSION

PLATELET TRANSFUSION

AFSHAN SHAMIMAFSHAN SHAMIM

B.S MT 3B.S MT 3RDRD YEAR 6 YEAR 6THTH SEMESTER SEMESTER

What are platelets?

    Platelets are blood cells that help control bleeding.  When a blood vessel is damaged, platelets collect at the site of injury and temporarily repair the tear.  They then activate substances in plasma which form a clot and allow the wound to heal. 

 

Plateletpheresis

Plateletpheresis is the process of collecting platelets.

Types Of Platelets:• Random Donor platelets (RDP) are

prepared from donated blood with in 4 to 6 hrs of collection by centrifugation & it contains approximately 5.5 x 1010 platelets.

• Single Donor Platelets (SDP) are prepared by platelet aphaeresis machine. One unit of SDP is equivalent to 5 to 10 units of RDP.

Low platelet count• A slightly lower platelet count will not

usually cause any problems• A very low platelet count, however, can

sometimes be serious• Signs of a low platelet count include

nosebleeds, bleeding gums, heavy periods, bruising and tiny blood spots in the skin or rashes.

When the patient bleeds??

Surgical bleeding due solely to thrombocytopenia occurs when platelets < 50,000/µL while spontaneous bleeding occurs when platelets < 10,000/µL.

Platelet Usage in Clinical Practice

• Indications  Platelet transfusion is NOT indicated for all thrombocytopenic patients

Indications for platelet tx..

Platelet transfusions are traditionally given

– Leukemia– aplastic anemia,– AIDS– hypersplenism,– Sepsis– bone marrow transplant– radiation treatment– organ transplant or surgeries such as

cardiopulmonary bypass.

Indications:

Prophylactic Therapeutic

Prophylactic Prophylactic platelet transfusions

reduce morbidity and improves patients’ quality of life but there is no evidence that it reduces mortality 

Prophylactic Platelet Transfusion

• Thrombocytopenia without any bleeding when the platelet count is < 5 x 109/L (Not applicable for ITP)

• In case of associated sepsis, DIC, fever or Amphotericin B therapy, transfuse at < 10 x 109/L

Therapeutic 

 Therapeutic platelet transfusions

used to arrest bleeding and reduces both morbidity and mortality 

Therapeutic Platelet Transfusion

• Intracranial hemorrhage • Severe profuse gum bleeding • Severe menorrhagia. • Emergency Surgery in a patient

with thrombocytopenia with platelets < 30 x 109/L before surgery

Avoid platelet tx in..• Platelet transfusions should be avoided in

those with TTP because it can worsen neurologic symptoms and acute renal failure, presumably due to creation of new thrombi as the platelets are consumed.

• It should also be avoided in those with heparin-induced thrombocytopenia (HIT) or disseminated intravascular coagulation

Immune thrombocytopenia.

• Platelet transfusions are generally not recommended

• antibodies destroy platelets, therefore any newly transfused platelets will also be destroyed.

Cardiopulmonary bypass surgery

Result in destruction of a large proportion of the patient's

platelets and may render the remaining viable platelets to be

dysfunctional. The indications for transfusion in such patients is

controversial.

Drug-induced platelet dysfunction.

The most common of these is aspirin, and its similar drug class, the NSAIDs. Other antiplatelet drugs are commonly prescribed for patients with acute coronary syndromes.When surgery is undertaken following the administration of these drugs, bleeding can be serious.

Expected platelet increase after transfusion

Platelet count increase as well as platelet survival after transfusion

is related to the dose of platelets infused and to the patient's body surface area

• Corrected platelet count increment (CCI) = platelet increment at one hr x BSA (m2) / # platelets infused x 1011

• Expected platelet increase = platelets infused x CCI / BSA (m2)

• The theoretical value of the CCI is 20,000/μL but clinically, the value is more close to 10,000/μL.

• If the CCI is less than 5,000/μL, patients are said to have "refractoriness" to platelet transfusion.

Who can be an apheresis donor?

• at least 17 year of age• in good health• weigh at least 110 pounds• not have taken aspirin or products

containing aspirin within 72 hours prior to donation.

Before collection…The donor must not take aspirin or

other anti-platelet medications for anywhere from 36 to 72 hours prior to donation. The reason for this is that aspirin can prevent platelets from adhering

Types of platelet collection???

Platelet concentrate

• Each unit of platelets separated from donated whole blood is called a "platelet concentrate".

• This greatly increases the risks of the transfusion

Apheresis • The donor's blood is processed in

a sterile single-use centrifuge, the unwanted components can be returned to the donor safely.

Soft-spin method(Platelet separation methodology

Soft" spin

platelet-rich plasma

Harder spin

Platelets suspended in a volume of about 50 mL of plasma

Life Span after Infusion:

Few hrs to maximum 24 hrs. This depends on whether the patient is

bleeding or not.

Efficacy• One unit of platelet RDP increases

platelet count by approximately 5 x 109/L (i.e. 5000 / mm3).

• SDP is as effective as RDP. SDP is more expensive & its use should be limited to cases of platelet refractoriness & in limiting donor exposure.

Checking platelet efficacy after tx

• An unconfirmed, but helpful, way to determine whether a patient is recovering from chemotherapy-induced thrombocytopenia is to measure "reticulated" platelets, or young RNA-containing platelets, which signifies that the patient is starting to make new platelets.

RefractorinessRefractoriness to platelet

transfusion will be defined in this review as a platelet count response to two or more platelet transfusions that is significantly less than expected.

RefractorinessThis can occur for two reasons:

non-immune causes andimmune causes.

However, becoming refractory to platelets is rare.

Non-immune causes• High temperature. Platelets are used

up faster if you have a high temperature.

• Antifungal drugs, can lower the platelet count

• Hypersplenism platelets can collect there instead of circulating in the bloodstream.

Immune causesPlatelets can become less effective

when immune system recognizes the donated platelets as different from own. body then produces antibodies The antibodies attack and destroy the platelets quickly

Possible side effects • Severe side effects from platelet

transfusions are rare.• The more common side effects include

– itching,– rashes,– a high temperature and shivering

(sometimes referred to as having a 'reaction').

Risks of platelet transfusions

– Bacterial contamination – Allergic reactions – Febrile reactions – Venous thromboembolism – TRALI

Side-effects of Platelet transfusion  

PLASMA: 200ml in each adult dose - ABO and other antibodies HTR - plasma proteins allergic reactions, anaphylaxis - passive tx of HLA/granulocyte antibodies TRALI 

LEUCOCYTES 

HLA antibody formation - non hemolytic febrile reactions  - refractoriness to platelet transfusions 

PLATELETS (HLA + HPA antigens) •

- HLA antibody stimulation - Refractoriness to tx - HPA immunization, antibody stimulation & rarely refractoriness and even more rarely, in females,

Management of these side effects

• Leukoreduction• gamma –irradiation• select HLA-compatible donors