Blood transfusion platelets

Whole blood is seldom used ia modem blood transfusion. Blood is separated into its components. Transfusion therapy optimizes the use of the blood components, using each for a specific need. Red cell concentrates are used for patients needing oxygen transport, platelets are used for hemostasis, and plasma is used as a volume expander or a source of proteins needed for clotting of the blood. 

Transfusion-induced autoimmune disease has been a significant complication in the treatment of patients who require multiple platelet transfusions. Platelets and lymphocytes carry their own blood group system, ie, the human leukocyte antigen (HLA) system, and it can be difficult to find an HLA matched donor. A mismatched platelet transfusion does not induce immediate adverse reactions, but may cause the patient to become refractory to the HLA type of the transfused platelets. The next time platelets with an HLA type similar to that of the transfused platelets are transfused, they are rejected by the patient and thus have no clinical efficacy. Exposure to platelets originating from different donors is minimized by the use of apheresis platelets. One transfusable dose (unit) of apheresis platelets contains 3-5 x 10 platelets. An equal dose of platelets from whole blood donation requires platelets from six to eight units of whole blood. Furthermore, platelets can be donated every 10 days, versus 10 weeks for whole blood donations. 

In contrast to hemodialysis that uses ultrafiltration membranes, plasma separation (also called plasmapheresis) requires microfiltration membranes with a pore size from 0.2 to 0.6 pm, in order to transmit all proteins and lipids, including LDL cholesterol (2000kDa) and retain completely platelets (2 pm diameter), red blood cells (8 pm diameter) and white blood cells. Thus, membrane plasmapheresis can yield high-quality platelet-free plasma and red cells can be either continuously returned to the donor or saved in another bag for blood transfusion. But it is important, in the case of plasma collection from donors, to minimize the membrane area, in order to reduce the cost of disposable hollow-fiber filters and to avoid the risk of hemolysis (free hemoglobin release) due to RBC damage by contact at the membrane if the pressure difference across the membrane is too high. 

Adverse effects. Haemorrhage occurs but is less of a problem with low doses of heparin it remains a particular risk in patients treated after failed fibrinol5 c therapy for acute myocardial infarction. Platelet transfusion after cessation of abciximab is necessary for refractory or life threatening bleeding. After transfusion, the antibody redistributes to the transfused platelets, reduces the mean level of receptor blockade and improves platelet function. Thrombocytopenia may occur from 1 hour to days after commencing treatment in up to 1% of patients. This necessitates platelet counts at 2-4 hours and then daily if severe, therapy must be stopped and, if necessary, platelets transfused. EDTA-induced pseudothrombocytopenia has been reported and a low platelet count should prompt examination of a blood film for agglutination before therapy is stopped. 

In a phase III trial in 190 patients with metastatic melanoma, sequential chemotherapy with dacarbazine, cisplatin, and vinblastine plus interferon alfa and aldesleukin modestly increased the response rates and produced considerably more frequent and severe adverse effects than chemotherapy alone (128). In particular, severe episodes of anemia and thrombocytopenia that required blood or platelet transfusions were 2-6 times more frequent in the chemotherapy group. 

Thrombocytopenia is a well-known consequence of hemodilution. It also occurs in blood transfusions, in which thrombocytopenia constitutes a more frequent chnical problem than abnormahties of coagulation (33). If the platelet count falls below 40 x 10 /1, platelet concentrates should be transfused. 

PlPlAl-negative platelets are used to treat neonatal alloimmune thrombocytopenic purpura, a rare, transient, but severe thrombocytopenia in the newborn due to platelet destruction by maternal antibody (1). The mother is usually a PlPlAl-negative person who has produced anti-PIPIAI as a result of previous blood transfusions or pregnancy. The antibody crosses the placenta and destroys the PIPIAI-positive platelets of the neonate. 

In patients with significant blood loss, blood transfusion may be indicated. This is generally in the form of packed red blood cells. The criteria for blood transfusion are controversial, but a hematocrit of 25% generally is accepted. In the individual patient, the decision is often determined by the overall chnical status and the ability of the patient to compensate for the reduction in oxygen-carrying capacity associated with an acute anemia. Additional blood component therapy with fresh frozen plasma or platelets is also based on the needs of the individual patient. Aggressive fluid therapy often must be continued in the postoperative period because fluid will continue to sequester in the peritoneal cavity, bowel wall, and lumen. 

Work carried out at the Theodor Kocher Institute was supported by grants from the Swiss National Science Foundation (31-42336.94) and Hoffmann-La Roche Ltd. The supply of bufly coats for the isolation of platelets by the Central Laboratory of the Blood Transfusion Service of the Swiss Red Cross is gratefully acknowledged. 

Mathias CJ, Welch MJ (1984) Radiolabelling of platelets. Semin Nucl Med 14 118-127 McAfee JG, Subramanian G, Gagne G (1984) Technique of leukocyte harvesting and labeling problems and perspectives. Semin Nucl Med 14 83-106 Mollison PL, Engelfriet CP, Contreras M (1987) The transfusion of platelets, leukocytes, haemo-poietic cells and plasma components. In Blood transfusions in clinical medicine. Blackwell, Oxford, pp 7-27... 

What should be considered in the elution of DEHP from PVC medical devices are fat-soluble agents and blood products into which DEHP may be eluted at high concentrations. The amount of DEHP that eluted into blood products stored in PVC bags was measured. When the amounts of DEHP in red blood cell products, whole blood products, blood platelet products, and blood plasma products were compared, a high concentration of DEHP was detected in whole blood products. This means that the sample matrix affects the elution of DEHP. We also analyzed blood products stored in PVC bags and found that the amount of DEHP eluted increased with the storage period, and the exposure to DEHP in an amount that exceeded tolerable dairy intake (TDI) value was noted after only one blood transfusion even if the blood product had not reached the expiration date. In addition, we established a method for the simultaneous analysis of DEHP and MEHP with high sensitivity and accuracy and... 

Blood components transfusion platelets, erythorocytes (when necessary) ... 

If blood or platelet transfusion are necessary for the above immunodeficiency disorders they must always be irradiated to prevent the risk of life-threatening Graft versus host disease (GVHD). 

A 76-year-old woman with seizures secondary to ischemic stroke developed status epilepticus despite treatment with clonazepam. She was given intravenous levetiracetam 1000 mg/day and 2 days later developed pancytopenia, with a hemoglobin concentration of 9.8 g/dl, a platelet count of 83 x 10 A, and a white blood cell count of 5.7 x 10 /1. These changes worsened during the next 4 days and she required blood transfusion. Levetiracetam was withdrawn and 2 days later the blood cell count improved. When rechallenge with oral levetiracetam 0.5 g/day 1 year later pancytopenia rapidly recurred. 

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