Anaesthesia
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As compared with European practice, the American approach to resuscitation from traumatic haemorrhage de-emphasises pre-hospital interventions in favour of rapid transport to definitive care; limits initial surgical interventions under the damage control model; uses crystalloid as the initial fluid of choice; and follows an empiric 1:1:1 approach to transfusion with red cells, plasma and platelets in hemodynamically unstable and actively bleeding patients. The use of bedside visco-elastic testing to guide coagulation support is not as widespread as in Europe, while the early administration of tranexamic acid is more selective.
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Understanding the complex immunological consequences of red cell transfusion is essential if we are to use this valuable resource wisely and safely. The decision to transfuse red cells should be made after serious considerations of the associated risks and benefits. ⋯ Red cell transfusions should be acknowledged as immunological exposures, with consequences weighed against expected benefits. This article reviews immunological consequences and the emerging evidence that may inform risk-benefit considerations in clinical practice.
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Peri-operative coagulation monitoring should begin with the assessment of individual bleeding risk using a standardised bleeding history before the surgical procedure. Laboratory testing should be performed if this history is abnormal or peri-operative bleeding is anticipated. ⋯ In bleeding patients, routine coagulation tests should be requested, but one should be aware of the major limitations that exist. Delay whilst waiting for these laboratory results, which, in turn, aggravates coagulopathy, bleeding, blood product requirements, length of surgery and overall morbidity and mortality.
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The aetiology and management of haemostatic abnormalities in critical care patients are considered in this narrative review. The mechanisms of normal haemostasis and derangements that occur as a result of sepsis and organ dysfunction are discussed. Finally, the management of haemostatic abnormalities as they relate to critical care practice are considered, including the management of heparin-induced thrombocytopenia.
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There is a considerable difference between the mechanism of action of the lysine analogues, tranexamic acid and epsilon-aminocaproic acid, and the serine protease inhibitor aprotinin. Aprotinin acts to inactivate free plasmin, but with little effect on bound plasmin, whereas the lysine analogues are designed to prevent excessive plasmin formation by fitting into plasminogen's lysine-binding site to prevent the binding of plasminogen to fibrin. Aprotinin is associated with a reduction in bleeding and transfusion requirements following major surgery, and has a dose-response profile, compared with no dose-response effect in the one study investigating tranexamic acid in cardiac surgical patients. Following its withdrawal in 2007, which is explained in detail in this review, the regulators have now licensed aprotinin for myocardial revascularisation only, which is relatively low-risk for bleeding.