Evidence and triggers for the transfusion of blood and blood products

Abstract

SummaryAllogeneic red cell transfusion is a commonly used treatment to improve the oxygen carrying capacity of blood during the peri-operative period. Increasing arterial oxygen content by increasing haemoglobin does not necessarily increase tissue oxygen delivery or uptake. Although the evidence-base for red cell transfusion practice is incomplete, randomised studies across a range of clinical settings, including surgery, consistently support the restrictive use of red cells, with no evidence of benefit for maintaining patients at higher haemoglobin thresholds (liberal strategy). A recent meta-analysis of 7593 patients concluded that a restrictive transfusion strategy was associated with a reduced risk of healthcare-associated infections (pneumonia, mediastinitis, wound infection, sepsis) when compared with a liberal transfusion strategy. The degree to which the optimal haemoglobin concentration or transfusion trigger should be modified for patients with additional specific risk factors (e.g. ischaemic heart disease), remains less clear and requires further research. Although most clinical practice guidelines recommend restrictive use of red cells, and many blood transfusion services have seen marked falls in overall usage of red cells, the use of other blood components such as fresh frozen plasma, platelets, and cryoprecipitate has risen. In clinical practice, administration of fresh frozen plasma is usually guided by laboratory tests of coagulation, mainly prothrombin time, international normalised ratio and activated partial thromboplastin time, but the predictive value of these tests to predict bleeding is poor.

Diagnostic criteria for pre-operative anaemia-time to end sex discrimination

“…The need to diagnose and manage pre‐operative anaemia is supported by the AAGBI, NHS Blood and Transplant, the British Society of Haematology and the National Institute for Health and Care Excellence (NICE) . However, the current standard of care for anaemic patients during surgical admission is management by red blood cell transfusion . Despite its effectiveness in ‘topping up’ haemoglobin, red cell transfusion does not address the underlying cause of the anaemia.…”

Assessment of the prescription of red blood cell concentrates in the pediatric age group

“…Normovolemic patients were shown to tolerate Hb concentrations between 5 and 6 g/dL. 3 Regardless of the cause of anemia (decreased production of red blood cells, hemolysis or bleeding), 4 the goal of transfusion is to normalize the transport of oxygen 2 and, therefore, the transfusion trigger has different values in different situations, ranging from Hb 7 g/dL in clinically stable children, [5][6][7][8] with acute bleeding 9 and sepsis but no shock; 10 to 7-8 g/dL in the postsurgical period, [11][12][13][14] and 10 g/dL in case of severe sepsis or septic shock. 15,16 Despite this knowledge, several services still adopt different transfusion protocols even for patients in similar clinical contexts, so that higher triggers relate to a greater frequency of transfusion reactions.…”

“…3,7,8,17,18 Transfusion is a mortality risk factor in critically ill children 19 and may cause immune and non immune-mediated reactions including, more frequently: febrile nonhemolytic transfusion reaction, hemolytic reaction, alergies, volume overload and infections. 1,2,5,20 Microcirculatory changes can also occur, 5,21 as well as increased incidence of cancers. 22 Reactions may occur in 0.95% 23 to 3.8% of cases.…”

Transfusion in critical care – a UK regional audit of current practice

“…The UK guidelines and the most recent Surviving Sepsis guidelines both suggest a threshold of 70 g.l À1 [4,[10][11][12] (Table 2). However, the Surviving Sepsis guidelines have a clause that effectively allows clinicians to exclude almost all critically ill patients.…”