Anemia of Critical Illness: A Concise Definitive Review in Critical Care

OBJECTIVES: Concise definitive review of anemia of critical illness. DATA SOURCES: Available literature on PubMed and MEDLINE databases. STUDY SELECTION: Available preclinical studies, clinical trials, observational studies addressing the diagnosis, pathophysiology, and treatment of anemia of critical illness were included. DATA EXTRACTION: Eligible studies were identified, and recommendations were summarized. DATA SYNTHESIS: Anemia of critical illness is highly prevalent, persists after ICU discharge and is associated with adverse outcomes. Most ICU patients have anemia of inflammation (high hepcidin, low erythropoietin, low erythroferrone, iron-restricted erythropoiesis) or iron deficiency anemia (low hepcidin). Dysregulation of iron homeostasis can also lead to the release of nontransferrin bound iron (catalytic iron), which catalyzes reactive oxygen species and is associated with organ failure in ICU patients. With significant advances in the understanding of the pathophysiology of anemia in the critically ill, new approaches to anemia management have emerged. Patient blood management, involving an evidence-based multidisciplinary approach with early diagnosis and diagnosis-specific treatment of anemia, optimizing hemostasis, and blood conservation including phlebotomy reduction, has become an increasingly important approach to patient care and represents a strategy that can result in improved patient outcomes in the critically ill. CONCLUSIONS: The high prevalence of anemia in ICU patients warrants a decisive shift from RBC transfusion as treatment to early proactive pathophysiology-based personalized treatment of anemia.