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Red cell transfusions for treating anaemia in the absence of bleeding

BMJ 2015; 350 doi: (Published 24 March 2015) Cite this as: BMJ 2015;350:h1463
  1. Timothy S Walsh, professor of critical care
  1. 1Department of Anaesthesia, Critical Care and Pain Medicine, Royal Infirmary of Edinburgh, Edinburgh University, Edinburgh EH16 4SA, UK
  1. twalsh{at}

Use a restrictive strategy in most patient groups

Transfusion of donated (allogeneic) red blood cells is life saving for patients with major bleeding, such as after major trauma or childbirth. However, probably less than 15% of the 85 million units of blood transfused globally each year are used to treat haemorrhagic shock; most are given to patients experiencing blood loss during surgery, or with chronic medical conditions or haematological malignancies.1 In these situations the circulating blood volume is either normal or can be restored with other fluids such as crystalloid solutions. For these patients it is uncertain when the benefits of supplementing oxygen carrying capacity by transfusing allogeneic blood outweigh the risks. In a linked updated meta-analysis Holst and colleagues (doi:10.1136/bmj.h1354) explore this issue by comparing more liberal with more restrictive transfusion practices and suggest that in many clinical situations a restrictive transfusion strategy does no harm and reduces patients’ exposure to potentially hazardous blood products.2

Red blood cells transport oxygen to cells. Non-anaemic adults transport about 1 litre of oxygen from the lungs to tissues every minute but use only 0.25 litres, creating a wide “safety margin.” When tissues acutely need more oxygen (for example during exercise), the cardiac output and the proportion of oxygen extracted from blood increase to maintain supply. The “anaerobic threshold,” …

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