• cardiac surgery;
  • preservation;
  • red blood cells

summary Effective, prolonged ex vivo storage of red blood cells is an essential requirement for inventory management of each nation’s blood supply. Current blood storage techniques are the development of a century of research. Blood undergoes metabolic and structural deterioration during prolonged ex vivo storage. Current regulatory requirements for the limit of blood storage do not consider oxygen delivery or clinical outcomes. Recently, concern that stored blood may produce adverse outcomes in recipients has sparked renewed interest in studies that can evaluate the clinical impact of fresh vs. stored blood. In 2008, a retrospective study of outcomes among transfused patients undergoing cardiac surgery suggested that blood stored for more than 14 days prior to transfusion led to higher perioperative mortality compared with blood stored for less than 14 days. Here, we critically examine the details of the above-mentioned study. Numerous substantial flaws in data analysis and presentation may have led to an erroneous conclusion about the effect of blood storage age and perioperative mortality. Given the fundamental importance of a safe and adequate blood supply to national healthcare, the question of the proper storage age for blood should be studied using a prospective study design.