Critical care : the official journal of the Critical Care Forum
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Preoperative anemia in a surgical patient predisposes to poor outcomes and allogeneic blood transfusions. As an alternative to transfusions, pharmacologic management of preoperative anemia with recombinant human erythropoietin (rHuEPO) has been well studied in many different types of surgery. rHuEPO, when used alone or in combination with preoperative autologous blood donation before elective surgery, stimulates erythropoiesis and helps to avoid or reduce the need for allogeneic blood transfusions. The clinical evidence on preoperative use of rHuEPO in orthopedic, cardiac, and cancer surgery, as well as in bloodless surgery, is reviewed.
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The decision to transfuse a hospitalized patient must balance the known risks of transfusion with the need to provide adequate tissue oxygenation and the appropriate utilization of blood as a scarce resource. The minimum tolerated hemoglobin level is not well established, and considerable variation exists in intensivists' transfusion practices. ⋯ Evidence from randomized trials also indicates that withholding transfusions may result in improved outcomes. Arbitrary numeric hemoglobin triggers, however, cannot supercede intervention based on individual physiologic need and clinical circumstances.
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Despite the increasing availability of data supporting more restrictive transfusion practices, the risks and benefits of transfusing critically ill patients continue to evoke controversy. Past retrospective and observational studies suggested that liberal transfusion strategies were more beneficial in patients whose hematocrit levels fell below 30%. An expanding body of literature suggests that an arbitrary trigger for transfusion (the '10/30 rule') is ill advised. ⋯ Based on the available evidence, transfusion in the critically ill patient without active ischemic heart disease should generally be withheld until the hemoglobin level falls to 7 g/dl. Transfusions should be administered as clinically indicated for patients with acute, ongoing blood loss and those who have objective signs and symptoms of anemia despite maintenance of euvolemia. The hemoglobin level at which serious morbidity or mortality occurs in critically ill patients with active ischemic heart disease is a subject of continued debate but it is likely that a set transfusion trigger will not provide an optimal risk-benefit profile in this population.
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The quality and economy of critical care could both be improved if blood losses due to phlebotomy and sampling from indwelling catheters for unnecessary diagnostic testing were curtailed. Practice guidelines can help to break bad diagnostic 'habits', such as fever work-ups that require substantial blood to be drawn yet typically yield little useful information. ⋯ Several devices allow blood that would otherwise be wasted during sampling to be returned to the patient aseptically. Point-of-care testing uses microliter quantities of blood, has acceptable precision, and can provide valuable diagnostic information while being minimally invasive.
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Anemia is a common problem in critically ill patients. It is caused, in part, by blood loss related to phlebotomy for diagnostic testing, occult gastrointestinal bleeding, renal replacement therapies, surgical intervention, and traumatic injuries. Reduced red cell life span and nutritional deficiencies (iron, folate, vitamin B12) may be other contributing factors. ⋯ The percentage of patients transfused in the ICU is inversely related to admission hemoglobin and directly related to age and severity of illness. Patients with an increased length of stay in the ICU are also at increased risk for receiving blood transfusions. Studies are needed to improve our understanding of the pathophysiology of ICU-acquired anemia, to determine the efficacy of blood transfusions in critical care, and to investigate alternatives to blood transfusion for the treatment of anemia in the ICU.