Critical care : the official journal of the Critical Care Forum
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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.
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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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Blood transfusions remain common practice in the critical care and surgical settings. Transfusions carry significant risks, including risks for transmission of infectious agents and immune suppression. Transmission of bacterial infections, although rare, is the most common adverse event with transfusion. ⋯ Numerous studies have been performed to examine the role of leukoreduction in decreasing these transfusion-related complications but results remain contradictory. We review the infectious risks associated with blood transfusion and the most recent data on its immunologic effects, specifically on cancer recurrence, mortality, and postoperative infections in surgical patients. We also review the use of leukoreduction in blood transfusion and its role in preventing transfusion-transmitted infections and immunomodulatory complications.