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Thrombocytes
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General Thrombocytes are essential for haemostasis. Complex reactions between thrombocyte receptors, phospholipids and thrombin lead to activation, platelet aggregation and the formation of a haemostatic ‘plug’. The goal of thrombocyte transfusion is to give the recipient a sufficient number of normally functioning thrombocytes for the purpose of stopping or preventing haemorrhages. Thrombocyte transfusions are usually ineffective in patients that have an elevated thrombocyte metabolism as a result of (auto) immuno-antibodies. With massive haemorrhages or use of aids that promote thrombocyte metabolism (aortic balloon pomp), the effect of the thrombocyte number after thrombocyte transfusion will be noticeable only after the haemorrhage is stopped or the aid is removed. Even medicinal products, such as Amphotericin-B, can negatively influence the yield from thrombocyte transfusion. Indication Thrombocyte transfusion is indicated for patients that have a serious shortage of circulating thrombocytes (thrombocytopoenia) or that have functionally abnormal thrombocytes (thrombocytopathy). Thrombocytes, leukocytes removed, are the standard product for the treatment of thrombocytopoenia and/or thrombocytopathy, if transfusion is appropriate. Generally, an administration is of 50 x 109 thrombocyte per 10 kg is sufficient (5 donor unites for one adult). Prophylactic thrombocyte transfusion is appropriate for patients with thrombocytopoenia as a result of bone marrow insufficiency and a thrombocyte amount in the peripheral blood < 10 x 109/L. Higher threshold values are recommended for newborns, namely:
Top Method of administration The presence of the swirling phenomenon must be checked before thrombocytes are distributed by the transfusion laboratory. The product must not be administered if there is an absence of swirling or the presence of (large) aggregates. Precaution It is advisable that every blood product be administered as rapidly as possible after arrival at the Department. Where possible, blood products should be administered during the day (for the monitoring of transfusion reactions). Blood product checks and identity The unit must always be carefully inspected prior to the transfusion to ensure it is intended for the patient concerned. At the bedside, check the identity and the ABO-blood group/Rhesus (D) factor of the patient, the data on the label of the blood product concerning ABO-blood group/Rhesus (D) factor, the expiry date, product code, and, if available, the result of the compatibility study. Before the administration the transfusion bag should also be visually checked for leakage and the presence of coagulants, contaminants or discolouration. Administration system An infusion for the administration of blood products may only be filled with physiological saline (NaCl 0.9%). A filter of 170 – 200 µm must be included in the administration system. For the administration, mix with blood products made decoagulant with citrate. NEVER use Ringers lactate or other calcium-containing fluids. Medicines must never be added to blood products or be connected to the infusion. A double lumen catheter (whereby the blood product is administered by the other line) must be employed when central lines are used for parenteral feeding. If no separate infusion line is available, then an already inserted line can be used (after pre-rinsing and after-rinsing with physiological saline) to transfuse erythrocytes or plasma. Thrombocytes must never be transfused with a used administration system. The administration system must be thoroughly rinsed with physiological saline both before and after every unit. Micro-aggregate filter (40 µm) may not be included in the administration system with thrombocyte transfusions. A peripheral administration system must preferably be replaced within 6 hours after the last transfusion Administration rate The infusion rate for all blood products must be slow during the first 10 minutes. The patient must be continuously observed for the occurrence of transfusion reactions with this. If these do not occur, then the administration rate can be adjusted as follows:
Warming of erythrocyte products The warming of erythrocyte products is exclusively indicated for extremely rapid transfusions (for adults, 50 – 100 ml/min). An especially validated blood warming apparatus is used for this, by which the supply hose is warmed. The bag with erythrocytes was not be warmed by immersing it in warm water. Thawing of plasma Fresh frozen plasma must be thawed at a maximum of 37 oC in equipment that is intended (validated) for such use. It should be occasionally turned during the thawing. If a water bath is used for the thawing, then the plasma must first be wrapped in a plastic liner. Plasma must NEVER be thawed in a domestic microwave oven. The plasma should be administered as rapidly as possible (maximum of 2 hours) after thawing. Handling transfusion reactions If cold chills, fever, blood pressure reductions, anaphylactic shock or shortness of breath occurs, then the blood product must be disconnected and the infusion transferred over to physiological saline in order to keep open the access to the bloodstream. A physician must be alerted. See transfusion reactions. Transfusion reactions must always be reported to the blood transfusion laboratory (transfusion reaction form). Administration The patient’s dossier must indicate which product code the administered blood products have, as well as the unit identification numbers. The dossier must also indicate which transfusion reactions may possibly have arisen. There is a statutory requirement that these data must be stored for a minimum of 10 years. Top Storage conditions The thrombocytes have a shelf life of 5 – 7 days when stored on a shaking apparatus in a thrombocyte storage cabinet where the temperature is between 20 and 24 °C. The shaking should be repeated as rapidly as possible after receipt at the hospital. If the product has not been stored shaking, then it must be administered as rapidly as possible (but at the latest within 6 hours) after release. The ambient temperature until the transfusion must not fall under 18 oC (thus, do not place in the refrigerator). The shelf life is 6 hours once the product has been injected. The screening for bacteriologic contamination, which is introduced immediately after preparation, may not show any growth of bacteria at the moment of release by the blood bank. When storing in the hospital, it must be possible to prevent a product from being released when the blood bank has reported that the culture is possibly positive. Compatibility Considering that ABO blood groups also arise with thrombocytes, thrombocytes must preferably be ABO identical or ABO compatible in order to be transfused. If the thrombocytes are suspended in 100% plasma, then this donor plasma must preferable by ABO compatible with the erythrocytes of the recipient, in particular when the product is administered to children. Matching tests or ABO compatibility research are not necessary. Erythrocytes are present in a thrombocyte product. Transfusion of thrombocytes from a Rhesus (D) positive donor to a Rhesus (D) negative patient can therefore be a provocation for the formation of antibodies against the Rhesus (D) antigen. If the prevention of anti-Rhesus (D) antibodies is indicated (in women up to 45 years of age) and if no Rhesus (D) negative thrombocytes are available, then there must be consideration given to intramuscular (or, with thrombocytopoenia/thrombocytopathy, subcutaneous) administration of 375 IU anti-Rhesus (D) Immunoglobulin. Evaluation of thrombocyte transfusions In particular, when the result of thrombocyte transfusion is doubted, it is worth recommending that the results of thrombocyte transfusion be evaluated by determination of the thrombocyte number in peripheral blood before, approximately 1 hour and/or approximately 24 hours after the transfusion (1 hour and 24 hour follow-up values, respectively). The follow-up values can be used to calculate the ‘corrected count increment’ (CCI):
A thrombocyte transfusion is considered to be effective with:
The clinical picture is also of importance for the evaluation of the results of thrombocyte transfusions.
Top Indication for HLA-selected or HPA-selected thrombocytes There is an indication for HLA-compatible or HPA-compatible thrombocytes if a thrombocyte transfusion of ABO-compatible random donors gives an insufficient 1 hour CCI-value at least twice, as well as when HLA-antibodies or HPA-antibodies have been demonstrated and clinical factors that are associated with elevated thrombocyte consumption have been ruled out. If not all of the points mentioned above have been fulfilled, then consideration can be given to a test transfusion of thrombocytes, with a determination of a 1 hour CCI. There must be timely consultation about HLA-compatible or HPA-compatible thrombocytes that occurs between the treating physician/head of the blood transfusion laboratory from the hospital and the transfusion physician from the regional Sanquin Blood Bank. This is in connection with the time required in order to select an appropriate donor, call this donor up, examine the donor, perform the extraction and test the product. Undesirable effects Undesirable effects that may occur during or after a transfusion include fever with or without cold chills, bacterial contamination, TRALI, GVHD, post-transfusion purpura (PTP), and infectious diseases. The product rarely induces (primary) HLA-immunisation without pre-existing antibodies against leukocytes. Considering the leukocyte removal, the product is considered to be as CMV-free as thrombocytes from anti-CMV antibody tested donors. Thrombocyte products
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