The identification of transfusion-transmitted infectious diseases, such as human immunodeficiency virus, in the past two decades has led to intense scrutiny of the blood supply. This attention has led to extensive screening of blood for infectious agents and a reexamination of transfusion practices. Shifts in practice have included a reduction in the transfusion threshold, a focus on blood conservation, and prestorage leukoreduction. During the last decade, we also witnessed a shift toward evidence-based transfusion practice, with an unprecedented number of clinical trials conducted to measure the benefit of red blood cell transfusion in terms of mortality and morbidity. These studies produced unexpected results, suggesting that red blood cell (RBC) transfusion may lack the predicted clinical benefit or even cause harm to the critically ill patient. This review will examine the clinical evidence for the benefit/harm of RBC transfusions and the possible adverse effects associated with changes in the RBC product that occur during storage. Anemia is a common occurrence in the critically ill; an estimated 30% of patients have hemoglobin of 100 g/L during their admission to an intensive care unit (ICU) (1). The most common therapeutic measure used to correct anemia is RBC transfusion; 25% to 37% of patients receive RBC products during their ICU stay in Canadian (2) and European hospitals (1), respectively. The rate of RBC transfusion in some studies reached 85% in patients spending 1 wk in an ICU, with “nosocomial anemia” from frequent blood sampling being a major contributing factor to transfusion (3). In a recent prospective observational cohort study (4), “reduced physiologic reserve” was the most common indication for transfusion (69%) in the critically ill. In contrast, only 31% of patients studied received a transfusion for hemorrhage (4).

Effects of storage on efficacy of red cell transfusion: when is it not safe?

Inhibition of erythrocyte Ca2+-ATPase by activated oxygen through thiol- and lipid-dependent mechanisms.

ObjectiveTo investigate the effects of endotoxin on adhesion of human red blood cells to human vascular endothelial cells under conditions of flow.DesignProspective, randomized, controlled in vitro study.SettingsUniversity-affiliated cell biology laboratory.SubjectsHuman erythrocytes and human vascu

Endotoxin promotes adhesion of human erythrocytes to human vascular endothelial cells under conditions of flow

Inhibition of the erythrocyte (Ca2+ + Mg2+)-ATPase by nonheme iron.

Red cell aging and active calcium transport

The effect of the thiol-oxidizing agent diamide on erythrocyte (Ca+2 + Mg+2)-ATPase activity was measured in normal and glucose-6-phosphate-dehydrogenase-deficient (G6PD-) cells. Although the enzyme activity before the oxidative stress was similar in both groups, diamide induced a markedly greater inhibition in the enzyme activity in the G6PD- cells than in the normal controls. These data indicate dependence of erythrocyte (Ca+2 + Mg+2)-ATPase, in part, on the redox status of the cell. The increased vulnerability of (Ca+2 + Mg+2)-ATPase to oxidative stress in G6PD- may be of pathophysiological relevance to their premature destruction in oxidant-induced hemolysis.

Vardiella Lavi

Papers

Erythrocyte (Ca+2 + Mg+2)-ATPase activity: increased sensitivity to oxidative stress in glucose-6-phosphate dehydrogenase deficiency.