Review article: risks of anemia and related management strategies: can perioperative blood management improve patient safety?
OBJECTIVE
Anemia in both acute and chronic conditions is associated with an increased risk of organ injury (brain, heart, kidney) and mortality. Thus, anemia is not "safe". Impairment of tissue oxygen delivery likely contributes as a central mechanism; however, the existing treatments for anemia (i.e., transfusion, erythropoiesis stimulating agents, blood substitutes) have not produced a demonstrable improvement in patient outcomes despite their efficacy to increase blood oxygen content. Indeed, transfusion of red blood cells (RBCs) has been attributed to increase mortality in non-bleeding patients. Thus, the pathophysiology of anemia-induced morbidity and mortality and its treatments are complex and incompletely understood. New knowledge continues to emerge regarding the cellular mechanisms that maintain oxygen homeostasis during anemia. Nevertheless, the application of this knowledge has not yet led to improvements in patient outcomes. As both anemia and transfusion are associated with increased mortality, utilization of multimodal patient blood management strategies may be effective in avoiding both of these predictors of adverse outcomes. We propose to review new strategies to avoid both anemia and transfusion with the goal of improving patient outcomes and safety.


RESULTS
We reviewed several approaches that utilize patient blood management to improve patient outcomes, including 1) characterization of biomarkers of anemia-induced tissue hypoxia to identify appropriate patient-specific treatment thresholds or hemoglobin (Hb) triggers; 2) development of adequately powered clinical trials that will help to define appropriate guidelines for the perioperative treatment of anemia and optimal Hb thresholds for transfusion of RBCs in specific patient populations; and 3) demonstration that an established blood conservation program (ONTraC) can reduce RBC transfusion and its associated adverse outcomes.


CONCLUSIONS
Anemia is associated with increased morbidity and mortality. Ongoing initiatives to treat anemia and optimize patient blood management may improve patient outcomes. A broader application of these approaches may improve the overall safety of anesthesia and surgery for patients with anemia.
Department of Anesthesia, Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada. hareg@smh.ca
Gregory M T
GM
Hare
John
J
Freedman
C
C
David Mazer
D000208:Acute Disease; D000740:Anemia / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D000758:Anesthesia / Q000009:adverse effects / Q000379:methods; D000818:Animals; D001803:Blood Transfusion / Q000379:methods*; D002908:Chronic Disease; D006706:Homeostasis; D006801:Humans; D017063:Outcome Assessment, Health Care; D010100:Oxygen / Q000378:metabolism; D019990:Perioperative Care / Q000379:methods*; D013514:Surgical Procedures, Operative / Q000379:methods; D065227:Transfusion Reaction
D010100:Oxygen