Transfus Apher Sci
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We review the experimental evidence showing systemic and microvascular effects of blood transfusions instituted to support the organism in extreme hemodilution and hemorrhagic shock, focusing on the use of fresh vs. stored blood as a variable. The question: "What does a blood transfusion remedy?" was analyzed in experimental models addressing systemic and microvascular effects showing that oxygen delivery is not the only function that must be addressed. ⋯ It is concluded that fresh RBCs are shown to be superior to stored RBCs in transfusion, however increased oxygen affinity may be a positive factor in hemorrhagic shock resuscitation. Although experimental studies seldom reproduce emergency and clinical conditions, nonetheless they serve to explore fundamental physiological mechanisms in the microcirculation that cannot be directly studied in humans.
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Thromboelastography (TEG) records the continuous profiles of whole blood coagulation by measurement of the viscoelastic changes associated with fibrin polymerization, and thereby provides a global assessment of haemostatic function. In the past decades there has been an increasing interest for TEG in clinical practice. In this paper we present the rationale for the method and a discussion of the possible application of TEG. ⋯ Currently TEG is used with standard coagulation tests to decrease the risk for bleeding and reduce the homologous blood transfusion in cardiac surgery with cardiopulmonary bypass and in liver surgery. Other applications are severe trauma, obstetric medicine, haemophilia and hypercoagulable conditions. Development of a modified TEG, using heparin in combination with reptilase and factor XIIIa, has the potential to monitor the effects of platelet inhibiting drugs. It should be kept in mind that the TEG is a global test of coagulation and therefore the need for additional haemostatic tests should be evaluated when applicable. The main advantage for TEG is an inexpensive patient near method for quick evaluation of the patient's global haemostatic system. Used by experienced hands, TEG is a valuable haemostatic test, the future of which is already present.
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Severe adverse events have been observed following the infusion of hemoglobin based oxygen carriers in patients subjected to elective orthopedic procedures, cardiopulmonary bypass surgery, and vascular surgical procedures. Along with all three of the hemoglobin based oxygen carriers, the patients received Ringer's D,L-lactate as the resuscitative fluid, Ringer's d,l-lactate in the excipient medium for the stroma free hemoglobin, and liquid preserved red blood cells that had been stored at 4 degrees C for longer than 2 weeks. ⋯ In a recent publication morbidity and mortality have been reported associated with the length of storage of red blood cells at 4 degrees C in patients subjected to reoperative cardiac surgery. Current clinical studies to assess the safety and therapeutic effectiveness of a hemoglobin based oxygen carrier (HBOC) must consider the effects of the composition of the resuscitation solution (Ringer's L-lactate), the composition of the excipient medium (Ringer's L-lactate or 0.9% NaCl) for the hemoglobin based oxygen carrier, and the length of storage of the liquid preserved red blood cells infused with the hemoglobin based oxygen carrier.
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Review
Role of nitric oxide in the prevention of severe adverse events associated with blood products.
The reduction in vitro of nitric oxide binding to the globin portion of hemoglobin (SNOHb) in fresh and liquid preserved red blood cells has been reported to be responsible for the severe adverse events (SAEs) associated with red blood cell transfusion. No in vivo data were reported that the reduction in SNOHb in red blood cells following transfusion was irreversible. In addition, no clinical data were reported that the reduction in SNOHb in red blood cells produced severe adverse events (SAEs) in recipients.
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The epidemiology of red cell transfusion is changing. Surgical use has decreased due to reduced transfusion triggers and better operative techniques. ⋯ The evidence for and against transfusion at different levels of anaemia is discussed. The appropriate level of haemoglobin at which to recommend transfusion depends on the indication for transfusion, the patient's co-morbidities and the quality of the red cells available.