Journal supplements, anemia management, and evidence-based critical care medicine

T he practice of critical care medicine is evolving rapidly, and the availability of clinical evidence is developing at a similar pace. At Critical Care Medicine, we have sought to provide our readers with the latest data rapidly and to aid them as they practice evidence-based critical care medicine. To that end, in the past year, we have reduced our average time to publication (from final acceptance of the manuscript) from approximately 12 months to just 4 months, while always striving to maintain the highest quality in the articles that we publish. Critical Care Medicine has the highest editorial ratings of any journal devoted to critical care medicine, and we are very proud of the quality, efficiency, and speed of our review process. We owe a debt of gratitude to our peer reviewers and publisher for making this possible. In addition, our corporate sponsors, including Ortho Biotech Products, LP, the supporter of this supplement to Critical Care Medicine, have provided us with much of the financial assistance necessary to publish additional pages and make this happen. Finally, we commend our authors and contributors for their hard work in responding quickly to our questions and comments throughout the review and publication process. This supplement presents a good example of the speed at which critical care medicine is evolving. Anemia in critically ill patients has been an area of intense discussion and research in recent years. We are pleased to present eight articles, all previously published in Critical Care Medicine, seven of which were published in the past 3 years. These articles summarize not only what we have learned about anemia and its treatment in critically ill patients, but also what we have yet to learn. The intent of this compendium is to compile all of these articles into a single issue, allowing for a convenient overview of the evidence on the subject. Anemia is a common occurrence in the intensive care unit (ICU); the prospective study by von Ahsen et al. (1) found that nearly 75% of critically ill patients develop anemia in the ICU, and one third of patients receive red blood cell transfusions. Other studies have suggested an even higher prevalence of anemia and blood transfusions in the ICU (2). Frequent phlebotomy, acute blood loss, and preexisting chronic illness are all recognized risk factors for anemia in the ICU, but recent evidence implicates another common factor, blunted erythropoietin response. An inappropriately low erythropoietic response has previously been demonstrated in anemia of chronic diseases, including cancer, inflammatory arthritis, human immunodeficiency virus, and chronic kidney disease. The prospective studies by von Ahsen et al. (1) in adults and Krafte-Jacobs et al. (3) in children demonstrate that critically ill patients have a blunted endogenous erythropoietin response to either anemia or hypoxemia. In each study, the authors concluded that treatment with recombinant human erythropoietin, a common intervention for anemia of chronic diseases, might also be beneficial in critically ill patients. Blunted erythropoietic response to anemia in the ICU has also been demonstrated in patients with multiple traumatic injuries. Hobisch-Hagen et al. (4) recently reported their findings from a prospective, observational study in which critically ill trauma patients demonstrated hypoferremia and a blunted erythropoietic response to anemia. These results led the authors to conclude that trauma patients in the ICU have a clinical presentation that most closely resembles anemia of chronic disease. An understanding of the etiology and pathophysiology of anemia in the ICU facilitates choosing an optimal treatment strategy. The primary treatment for anemia in the ICU has, of course, been blood transfusion. Casutt et al. (5) sought to determine what factors influence oxygen delivery and consumption, the most important goals of blood transfusion. In cardiovascular surgery patients, they identified pretransfusion measures of oxygen delivery and oxygen consumption as predictors of transfusion response. In addition, this study confirmed prior evidence that allogeneic transfusion improves oxygen delivery but not oxygen consumption. The relationship between cardiovascular disease and anemia in the ICU is a complex one and has been an active area of research. Rady et al. (6) performed a cohort study in patients $75 years of age who were admitted to the ICU after cardiac surgery. The presence of anemia before or during ICU stay was among the factors that significantly increased the risk of morbidity and mortality in these patients. The authors recommended anemia avoidance to improve outcomes in elderly patients after cardiac surgery. Hebert et al. (7) recently reported on a subset of volume-resuscitated patients with cardiovascular disease from a multicenter, randomized, controlled trial. Critically ill patients were randomized to a restrictive transfusion strategy (“trigger” of hemoglobin (Hb), ,7 g/dL; target Hb, 7–9 g/dL) or a liberal transfusion strategy (Hb trigger, 10 g/dL; target, 10–12 g/dL). Overall mortality and morbidity was not significantly different between groups, but survival tended to decrease for patients with preexisting ischemic heart disease (especially those with acute myocardial infarction or unstable angina) in the restrictive transfusion strategy group, suggesting that critically ill patients with heart and vascular disease may benefit from higher Hb. This From Rush-Presbyterian-St. Luke’s Medical Center, Chicago, IL. Copyright © 2001 by Lippincott Williams & Wilkins