Providing universal access to blood supplies is a key objective for global health agencies. The World Health Organization is committed to establishing national blood systems in all countries to ensure that blood is available. Nevertheless, there is remarkably little evidence from randomised controlled trials on what types of patients benefit from blood transfusions, what blood products should be transfused, and how much patients should receive. Indeed, a 2008 systematic review of the association between blood transfusion and morbidity and mortality in high-risk hospitalised patients concluded that transfusions are associated with increased morbidity and mortality and urged that transfusion practices should be re-evaluated. Furthermore, even if a blood transfusion is indicated, there are risks associated with transfusion. Although in high-income countries blood is screened for infections, in some low-income countries, donated blood is not adequately screened and patients are at risk of contracting infections such as human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) through blood transfusions. The identification of strategies to minimise exposure to blood is therefore of considerable global health importance.
This collection of Cochrane Reviews summarises the evidence for the safety and effectiveness of interventions to reduce the need for blood transfusion. For some interventions the evidence is strong. For example, there is reliable evidence that the antifibrinolytic agent tranexamic acid safely reduces mortality in bleeding trauma patients and that antifibrinolytic drugs reduce bleeding and exposure to allogeneic blood transfusion in elective surgery. Given the increasing global burden of trauma and the risk of HIV, HBV, and HCV from blood transfusion in many parts of the world, a strong case can be made for ensuring universal access to tranexamic acid, which also happens to be an inexpensive treatment. Indeed, efforts to ensure universal access to safe blood without taking steps to reduce the need for blood transfusion seem inappropriate. Trials currently underway of tranexamic acid in post-partum bleeding may add further indications, and if so would strengthen the case for universal access. Cell salvage, which involves collecting the patient's own blood from surgical sites and transfusing it back into the patient, appears promising, but larger high-quality trials are needed. A review of transfusion thresholds suggests that giving less blood is safe and that blood transfusion is not essential unless haemoglobin levels drop below 7 or 8 g/dL, although further trials are needed to inform practice in patients with heart problems. For other interventions the jury is still out and further trials are needed. However, the evidence in this collection deserves careful consideration by all those who may have to give or receive a blood transfusion.
The Cochrane Reviews highlighted here have been prepared by the authors and editors of the Cochrane Injuries Group.
Antifibrinolytic drugs are widely used, particularly in cardiac surgery, and previous reviews have found them to be effective in reducing blood loss, the need for transfusion, and the need for re-operation due to continued or recurrent bleeding. In the past few years questions have been raised regarding the comparative performance of the drugs. The safety of the most popular agent, aprotinin, has been challenged, and it was withdrawn from world markets in May 2008 because of concerns that it increased the risk of cardiovascular complications and death. This review assesses the comparative effects of the antifibrinolytic drugs aprotinin, tranexamic acid, and epsilon aminocaproic acid on blood loss during surgery, the need for red-blood-cell transfusion, and adverse events, particularly vascular occlusion, renal dysfunction, and death.
Uncontrolled bleeding is an important cause of death in trauma victims. Antifibrinolytic treatment has been shown to reduce blood loss following surgery and may also be effective in reducing blood loss following trauma. This review aims to quantify the effect of antifibrinolytic drugs in reducing blood loss, transfusion requirement and mortality after acute traumatic injury.
Fibrin sealants (also referred to as biological glue or fibrin tissue adhesives) have gained increasing popularity as interventions to improve peri-operative (intra- and post-operative) haemostasis and diminish the need for allogeneic red-cell transfusion (blood from an unrelated donor). This review examines the efficacy of fibrin sealants in reducing peri-operative blood loss and allogeneic red-blood-cell transfusion.
Public concerns regarding the safety of blood transfusions have prompted reconsideration of the use of allogeneic blood transfusion, and a range of techniques have been designed to minimise transfusion requirements. This review examines the efficacy of desmopressin acetate (1-deamino-8-D-arginine-vasopressin) in reducing peri-operative blood loss and the need for red-blood-cell transfusion in patients who do not have congenital bleeding disorders.
'Cell salvage' or 'autotransfusion' involves the collection of a patient's own blood from surgical sites which can be transfused back into the same person during or after surgery, as required. This review assesses the evidence for the efficacy of cell salvage in reducing allogeneic blood transfusion and the evidence for any effect on clinical outcomes.
Platelet-rich plasmapheresis is a technique that involves a patient's own blood (autologous whole blood) being withdrawn via an intravenous catheter into a device that separates the blood by centrifugation into red blood cells, plasma, and a highly concentrated platelet solution. This concentrated autologous platelet solution is returned to the patient at the end of the operation to optimise blood clotting and minimise bleeding. This review examines the evidence for the efficacy of platelet-rich plasmapheresis in reducing peri-operative allogeneic red-blood-cell transfusion, and the evidence for any effect on clinical outcomes such as mortality and re-operation rates.
Most clinical practice guidelines recommend restrictive red-cell transfusion practices, with the goal of minimising exposure to allogeneic blood. This review aims to examine the evidence for the effect of transfusion thresholds on the use of allogeneic and/or autologous red-cell transfusion, and the evidence for any effect on clinical outcomes.
Treatment of haemorrhagic shock involves maintaining blood pressure and tissue perfusion until bleeding is controlled. Different resuscitation strategies have been used to maintain the blood pressure in trauma patients until bleeding is controlled. However, while maintaining blood pressure may prevent shock, it may worsen bleeding. This review assesses the effects of early versus delayed, and larger versus smaller volume of fluid administration in trauma patients with bleeding.
Acknowledgements: Ian Roberts, Co-ordinating Editor, and Emma Sydenham, Managing Editor, of the Cochrane Injuries Group for drafting the introductory text and selecting Cochrane Reviews for inclusion.
Image credit: Tek Image/Science Photo Library, M532/0683
Date published: 11 July 2012
Contact: Cochrane Editorial Unit (firstname.lastname@example.org)