Transfusion Practice

Abstract

BACKGROUND:

Most clinical practice guidelines recommend restrictive red cell transfusion practices, with the goal of minimising exposure to allogeneic blood. The purpose of this review is to compare clinical outcomes in patients randomised to restrictive versus liberal transfusion thresholds (triggers).

OBJECTIVES:

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.

SEARCH METHODS:

Summary This study provides further evidence that Hb measurement alone is an inadequate transfusion trigger as it does not accurately measure changes in red cell volume (RCV), plasma volume (PV) and blood volume (BV). Slight and colleagues designed this study to record changes in the above at various time points in 30 adult patients scheduled for elective cardiac surgery. Procedures included coronary artery bypass and/or valve replacement surgery.

Summary Observing that nearly 37% of patients in their medical intensive care unit (ICU) received inappropriate red blood cell (RBC) transfusions (defined as outside evidence-based indications) investigators from the Mayo Clinic conducted this quality improvement intervention aimed at reducing potentially harmful and inappropriate transfusions. The authors developed an evidence-based RBC transfusion algorithm. After endorsement by key opinion leaders the algorithm was communicated widely to staff via a number of educational forums.

Summary Madjdpour, Heindl and Spahn present a very useful review of current estimations of red blood cell (RBC) transfusion efficacy, risks, side effects, indications and alternatives, particularly relating to the perioperative period. The authors briefly review the physiology of oxygen transport and the compensatory mechanisms in anemic patients and the effects of RBC transfusion on oxygen delivery and consumption (DO2 and VO2).

Summary This report updates and expands “Practice Guidelines for Blood Component Therapy” adopted by the American Society of Anesthesiologists in 1995 (abstract). A multidisciplinary 10-member Task Force conducted a literature review (1994-2005), obtained opinions from a panel of experts, conducted surveys of members on the strategies and draft guidelines, and sought input from open forums.

Summary Karkouti and colleagues present a clinical predictive rule to identify patients at risk of massive blood transfusion (defined as ≥5 units of RBCs transfused within one day of surgery) following cardiac surgery. A multivariate predictive rule and risk score was developed and validated. In 10,667 consecutive patients undergoing cardiac surgery at their institution 6,651 were assigned to a training set and 4,016 to a validation set.

Summary As there is little evidence to guide platelet transfusion in critically ill patients in intensive care, Arnold and colleagues conducted this retrospective study to provide a basis for establishing recommendations and defining best practice. They sought to identify platelet (PLT) transfusion indications, triggers and effect on PLT counts. 261 patients meeting study criteria were enrolled. 45% (118) were thrombocytopenic and of these, 27 received PLT transfusions.

Summary Despite the lack of evidence, transfusion of fresh frozen plasma (FFP) for an assumed coagulopathy based on abnormal laboratory coagulation values remains a frequent practice. In this prospective audit, investigators from the Massachusetts General Hospital sought to evaluate the effect of FFP transfusion on laboratory coagulation values and if there was any correlation between the pretransfusion prothrombin time (PT), international normalized ratio (INR) and evidence of bleeding.

              Summary   This multicenter randomized controlled trial found no indication of harm from a restrictive transfusion threshold in acutely ill extremely low birth weigh infants. 10 international centers participated in this trial comparing clinical outcomes in 451 extremely low birth weight infants (<1000 g) randomly assigned during the first two days of life to either a restrictive (low) or a liberal (high) transfusion threshold algorithm. Hemoglobin level transfusion thresholds varied according to age and level of respiratory support needed.