Transfusion
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Patients who present with fulminant hepatic failure due to Wilson's disease may develop hemolytic anemia and renal insufficiency. In this entity, acute hepatocellular necrosis triggers the release of copper ions into the circulation, which leads to toxic effects on red cell metabolic pathways and hemolysis. ⋯ Plasma exchange allows a rapid reduction in elevated serum copper levels in patients with fulminant Wilson's disease. This leads to an amelioration of hemolytic anemia and provides clinical stabilization until liver transplantation can be performed.
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In subjects who have undergone acute preoperative normovolemic hemodilution (ANH), intraoperative hemorrhage is generally treated by immediate return of autologous blood collected during ANH. Simply increasing blood oxygen content by hyperoxic ventilation (HV, inspiratory fraction [FIO2] 1.0) might compensate for the acute anemia, allow further ANH, and delay onset of autologous blood return. ⋯ In anesthetized dogs ventilated with room air and hemodiluted to a Hb of 7 g per dL, simple oxygen therapy by HV (FIO2 1.0) rapidly improves tissue oxygenation and permits extended hemodilution to Hb of 5.8 g per dL until the HV-induced effects are lost.
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Intravenously administered perfluorocarbon (PFC) emulsions increase oxygen solubility in plasma. PFC might therefore temporarily replace red cells (RBCs) lost during intraoperative hemorrhage. In patients who have undergone hemodilution, the return of autologous blood may be delayed by the administration of PFC, and autologous RBCs may be saved for transfusion after surgical bleeding is stopped and PFC is cleared by the reticuloendothelial system. ⋯ Bolus intravenous administration of 60-percent (wt/vol) perflubron emulsion and further hemodilution from a Hb of 7 g per dL to one of 3 g per dL were as effective as autologous RBC transfusion in maintaining tissue oxygenation during volume-compensated blood loss designed to mimic surgical bleeding.
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To investigate how a delay between pretransfusion platelet count measurement and actual platelet transfusion affects the assessment of platelet transfusion responses, the rate of reduction in platelet counts was determined in 30 patients with relatively uncomplicated thrombocytopenia. ⋯ The rate of reduction in platelet count can have a significant impact on the evaluation of platelet transfusion responses when there is a delay between pretransfusion measurement of platelet count and the initiation of platelet transfusion. In addition, the rate of platelet reduction determined from this study can be used to confirm an accelerated rate of platelet consumption in thrombocytopenic patients.
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North American transfusion guidelines do not stipulate a time limit between drawing the specimen for pretransfusion testing and giving the transfusion to patients who have not received a transfusion or been pregnant in the preceding 3 months. British guidelines suggest that separated plasma and serum can be stored at -30 degrees C for up to 6 months, but they draw attention to the paucity of evidence concerning the use of stored samples. In Australia, transfusion guidelines recommend a maximum of 10 days' validity for pretransfusion specimens, which requires the patient to present for pretransfusion testing within 10 days of admission or to undergo retesting after admission, which in turn necessitates additional time in the hospital before operation. The study was performed to document the safety of using for pretransfusion testing a blood sample collected more than 10 days before surgery. ⋯ For patients who have not been transfused or pregnant in the previous 3 months, it is safe to crossmatch blood for transfusion by using a sample collected well in advance of elective surgery and stored at -30 degrees C.