Current status of red-cell preservation and availability in relation to the developing national blood policy

Restrictive and liberal red cell transfusion strategies in adult patients: reconciling clinical data with best practice

Red blood cell (RBC) transfusion guidelines correctly promote a general restrictive transfusion approach for anemic hospitalized patients. Such recommendations have been derived from evaluation of specific patient populations, and it is important to recognize that engaging a strict guideline approach has the potential to incur harm if the clinician fails to provide a comprehensive review of the patient’s physiological status in determining the benefit and risks of transfusion. We reviewed the data in support of a restrictive or a more liberal RBC transfusion practice, and examined the quality of the datasets and manner of their interpretation to provide better context by which a physician can make a sound decision regarding RBC transfusion therapy. Reviewed studies included PubMed-cited (1974 to 2013) prospective randomized clinical trials, prospective subset analyses of randomized studies, nonrandomized controlled trials, observational case series, consecutive and nonconsecutive case series, and review articles. Prospective randomized clinical trials were acknowledged and emphasized as the best-quality evidence. The results of the analysis support that restrictive RBC transfusion practices appear safe in the hospitalized populations studied, although patients with acute coronary syndromes, traumatic brain injury and patients at risk for brain or spinal cord ischemia were not well represented in the reviewed studies. The lack of quality data regarding the purported adverse effects of RBC transfusion at best suggests that restrictive strategies are no worse than liberal strategies under the studied protocol conditions, and RBC transfusion therapy in the majority of instances represents a marker for greater severity of illness. The conclusion is that in the majority of clinical settings a restrictive RBC transfusion strategy is cost-effective, reduces the risk of adverse events specific to transfusion, and introduces no harm. In anemic patients with ongoing hemorrhage, with risk of significant bleeding, or with concurrent ischemic brain, spinal cord, or myocardium, the optimal hemoglobin transfusion trigger remains unknown. Broad-based adherence to guideline approaches of therapy must respect the individual patient condition as interpreted by comprehensive clinical review.

Red blood cell storage: how long is too long?

Red blood cells (RBCs) undergo biochemical and structural changes during storage, commonly referred to as the "storage lesion." Evidence suggests that the longer the RBC product is stored, the less effective is the transfused blood. Many studies linking morbidity to transfusion have not considered duration of RBC storage as a variable that may modulate the effect. In addition, the effects of supply and demand and RBC inventory management strategies have been incompletely investigated. It is possible to envision a blood management system based on modern inventory management strategies that could greatly reduce storage duration.

Controversies in RBC Transfusion in the Critically Ill

Transfusion practice has been under great scrutiny over the last 2 decades. The examination of transfusion risks and benefits have been particularly important in the critically ill patient population. This review will examine some of the important controversies still surrounding the use of RBC transfusion in the critically ill patient.

Clinical consequences of red cell storage in the critically ill

Red cell (RBC) transfusions are a potentially life-saving therapy employed during the care of many critically ill patients to replace losses in hemoglobin to maintain oxygen delivery to vital organs. During storage, RBCs undergo a series of biochemical and biomechanical changes that reduce their survival and function. Additionally, accumulation of other biologic by-products of RBC preservation may be detrimental to recipients of blood transfusions. Laboratory studies and an increasing number of observational studies have raised the possibility that prolonged RBC storage adversely affects clinical outcomes. In this article, the laboratory and animal experiments evaluating changes to RBCs during prolonged storage are reviewed. Subsequently, the clinical studies that have evaluated the clinical consequences of prolonged RBC storage are reviewed. These data suggest a possible detrimental clinical effect associated with the transfusion of stored RBCs; randomized clinical trials further evaluating the clinical consequences of transfusing older stored RBCs are required.

A pilot trial evaluating the clinical effects of prolonged storage of red cells

The clinical consequences of prolonged storage of red cells have not been established. In this pilot study, we evaluated whether it would be feasible to provide a continuous supply of red cells stored <8 days. In addition, we examined the potential benefits attributed to "fresh" as compared to standard red cells in 66 critically ill and cardiac surgical patients. Nine patients were issued red cells but were not transfused. From the 57 remaining patients, the number of units transfused averaged 5.5 +/- 8.43 red cell units in the experimental group compared to 3.3 +/- 3.27 red cell units in the standard group (P = 0.25). The median storage time was 4 days in the experimental group compared to 19 days in the standard group (difference of 15 days; interquartile range of 12-16 days; P < 0.001). Overall, 73% of patients received red cells with storage times that corresponded to the treatment allocation more than 90% of the time. The group receiving red cells <8 days old tended to be older on average (68 +/- 8.54 yr versus 63 +/- 15.30 yr; P = 0.13) and have more comorbid illnesses (85% versus 65%; P = 0.09). In total, 27% of patients in the experimental group died or had a life-threatening complication as compared to 13% in the standard group (P = 0.31). There were no differences in prolonged respiratory, cardiovascular, or renal support after randomization (P > 0.05). A large clinical trial comparing red cell storage times is feasible and warranted given the limited available evidence.

Effect of different resuspension media on the post-thaw characteristics of frozen blood

Red blood cells frozen by the low-glycerol fast-freezing technique were thawed, deglycerolized and resuspended in various media. The use of ACD-saline for resuspension markedly reduced in vitro haemolysis such that the red cells could be transfused up to 5 d after thawing. At this time the cells contained satisfactory levels of potassium and organic phosphates, while bacterial contamination was negligible. For the past 4 years we have operated a small bank of previously frozen red blood cells which were thawed and resuspended in this way. Over 3500 units have been transfused after 1--5 d post-thaw storage without untoward effects.

Autologous blood transfusion

Autologous blood transfusion is a procedure in which blood is removed from a donor and returned to his circulation at some later time. Autologous transfusion can be performed in three ways: (1) preoperative blood collection, storage, and retransfusion during surgery; (2) immediate preoperative phlebotomy with subsequent artificial hemodilution and later return of the phlebotomized blood; and (3) intraoperative blood salvage and retransfusion. All three methods of autologous transfusion offer a potentially superior method of blood transfusion which eliminates many of the problems and complications associated with the banking and administration of homologous donor blood.

Lymphocyte response to blood transfusion in man: a comparison of different preparations of blood

The appearance of atypical lymphocytes in post-transfusion blood, their incorporation of tritiated thymidine in tissue culture and the elimination of cytotoxic antibody production, have been used as markers to show that frozen red cells are the least immunogenic when compared with dextran sedimented blood and whole blood donations. The absence of atypical lymphocytes and failure to produce lymphocytotoxic antibodies after transfusion of frozen cells is highly significant (P is less than 0.001) when compared with whole blood donations.

Effect on cytotoxicity antibodies in potential transplant recipients of leucocyte-poor blood-transfusion

In a controlled clinical trail, 40 uraemic patients received only leucocyte-poor blood (L.P.B.) while 30 uraemic controls received whole blood and ordinary packed red blood-cells (R.B.C.). Alloimmunisation by HL-A antibodies was found in 15% of the study group and 52% of the control group. Thus, L.P.B. was significantly less likely to produce alloimmunisation than ordinary whole blood or R.B.C. transfusion. Frozen R.B.C may produce even less alloimmunisation, but the advantages of L.P.B. include lower cost, prolonged storage, and ready availability in emergencies.