Infection - a downside of blood transfusion therapy

Around a third of critically ill patients are given transfusion of packed red cells but there is an ever-growing body of research evidence to suggest that blood transfusion may not be as beneficial to all patients as was once supposed. 

Some studies, for example, have revealed that patients given transfusion might be more susceptible to hospital-acquired (nosocomial) infection, a notion that is revisited in a recently published retrospective study of over 2000 intensive care patients. The case records of all 2432 adult patients admitted to a 24-bed ICU over a period of 2 years were retrieved for this study. 

Of these 2432 patients, 609 received at least one red-cell transfusion. Infection acquired after admission to the unit occurred in 10.5 % of patients given transfusion compared with only 4.9 % of those not transfused. This confirms previous work that has revealed an association between red-cell transfusion and increased risk of infection. 

New findings from this study relate to the relationship between transfusion and causative organism of infections and the question as to whether or not transfusion is associated with particular susceptibility to some invading organisms. 

In fact nearly all bacterial species, both Gram positive and Gram negative, were cultured more frequently in those transfused than those not transfused, suggesting that the increased rate of infections in transfused patients reflects a generalized increased susceptibility to infection. However, this increased susceptibility was found to be particularly marked for one bacterial species, Acinetobacter spp. 

This species accounted for just 2 % of bacterial infections in the non-transfused group compared with 15 % in the transfused group. Study investigators state that the particular vulnerability of transfused patients to Acinetobacter spp, suggested for the first time by results of their study, requires confirmation and is worthy of further investigation. 

On a more general note red-cell transfusion was found to be independently associated with not only increased risk of infection but also increased length of stay in intensive care (i.e. prolonged illness) and increased risk of death before discharge from ICU. 

In discussion of their findings the authors of this study speculate that the adverse effects of red-cell transfusion revealed by this and a number of other studies might be mitigated by the use of freshly donated red cells. Current practice is to transfuse red cells that have been stored for up to 30 days after donation.