Epidemics of Dengue and Leptospirosis is not new every monsoon in India. So also acute shortage of Platelets; product like FFP is very often substituted in case of nonavailability of platelets in Blood Bank. "The Best Blood Is Still the one that you have not received".
Facts About Platelet TransfusionTypes 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.
Storage: 22 degree C on a constant agitator. DO NOT STORE PLATELETS IN THE REFRIGERATOR.
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.
Adults: 1 unit RDP for every 10 kgincreases platelet count by approximately 50 x 109/L (50,000/cumm).
Pediatric: 0.2 unit/kg of RDP will raise the platelet count to 50 x 109/L (50,000/cumm.)
Blood Group & Platelets: Normal platelets express ABO antigens on their surface. They do not express Rh D antigen. RDP of the same Blood group is recommended; in case of an emergency RDP of any blood group can be administered. Rh-negative women in reproductive age group should receive Rhogam (Anti D) if they receive RDP from an Rh + ve donor, to prevent Rh sensitization from contaminating RBCs. SDP donor should be of the same blood group.
Decision Making In Platelets TransfusionsDecision to transfuse platelets depends upon the
- Clinical Condition of Patient
- Cause of thrombocytopenia
- Platelet count & function
- Treating physician experience & comfort level (TREAT THE PATIENT & NOT THE PLATELET COUNT)
Risk of life-threatening hemorrhage is approximately 1 %. Risk of bleeding increases with concomitant secondary infection, fever, DIC, Amphotericin B Therapy & Drugs like NSAID'S.
Platelet transfusions are not indicated for skin bleed like petechiae, purpura, and ecchymosis. A good dictum to follow in patients of Thrombocytopenia is "If the patient is not bleeding do not transfuse platelets".
Prophylactic Platelet Transfusion:
Is suggested in a patient with thrombocytopenia without any bleeding when the platelet count is < 5 x 109/L (5000/cu mm). (Not applicable for ITP)
The threshold for prophylactic platelet transfusion has been lowered from the previous threshold of 20 x 109/L (20,000/cu mm) platelet count.
In case of associated sepsis, DIC, fever or Amphotericin B therapy, transfuse at < 10 x 109/L (10,000/cu mm).
Therapeutic Platelet Transfusion is given in a patient with thrombocytopenia if there is life threatening bleed like:
- Intracranial hemorrhage
- Hematemesis, malena
- Severe profuse gum bleeding
- Severe menorrhagia
- Emergency Surgery in a patient with thrombocytopenia with platelets < 30 x 109/L (30,000/cumm); raise platelet count to at least > 50 x 109/L (50,000 /cumm) before surgery.
Contraindications for Platelet Transfusions- Platelet Transfusions are inappropriate in ITP as survival of transfused platelets is very brief, as short as few minutes.
- Heparin induced thrombocytopenia (HITT)
- Thrombotic thrombocytopenic purpura (TTP)
Hazards of Platelet Transfusion - Due to the storage temperature of 220C, there is higher risk of febrile non-hemolytic transfusion reactions (FNHTR) & bacterial contamination.
- Transmission of viral infections like HbsAg, HCV, HIV, HAV, Parvovirus
Administration of PlateletsProcure platelets from the blood bank only prior to transfusion. Infuse platelet immediately upon arrival to the hospital. DO NOT STORE PLATELETS IN HOSPITAL REFRIGERATOR. Administer Platelets through a separate IV line. Do not routinely give pre transfusion medications. Check patient's vital parameters before starting platelet transfusion. Begin with a slow infusion rate; if there is no reaction infuse rapidly so as to complete all platelets with in an hour. Monitor the patient's vital parameters through out infusion. Check platelet count 1 hr and 24 hrs after transfusion to judge adequacy of platelet transfusion. Use a blood transfusion filter set with an in line filter; Leucodepletion filter sets specific for platelet Transfusion are available and should be used in an affording patient. Leucodepletion filter removes viable leucocytes and prevents FNHTR, transmission of CMV infection & delays platelet refractoriness. Leucodepletion however do not prevent TaGvHD (Transfusion associated Graft versus Host disease). Irradiating platelets before infusion can prevent TaGvHD.