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Transfusion for Anaemia in Critically Ill Patients Depends on Clinical Condition and Comorbidities

A DGReview of :"Anaemia and red blood cell transfusion in the critically ill patient"
Blood Reviews

11/10/2003
By Mary Beth Nierengarten


The decision to treat anaemia with transfusion of allogeneic stored red blood cells (RBCs) in critically ill patients is currently based on clinical judgement because there are no universal triggers that indicate the need for transfusion.

In a review of anaemia and RBC transfusion in critically ill patients, SA McLellan, MD, Royal Infirmary of Edinburgh, Scotland, and colleagues provide a summary of the current evidence on the prevalence and causes of anaemia in this patient group, indications for RCB transfusion, and the efficacy of transfusion.

Because of differences in case-mix and severity of anaemia among intensive care units throughout the world, the prevalence of anaemia in critically ill patients varies, however, studies show that many patients are anaemic on admission to the ICU, are at risk of developing anaemia the longer they stay in the ICU, and remain anaemic when discharged from the ICU.

Although several factors play a role in the development of anaemia in critically ill patients, including blood loss, decreased RBC production, and increased RBC destruction, current evidence suggests that whole blood loss (primarily from phlebotomy) and blunted erythropoietic response are the main determinants.

In the absence of well-founded clinical indicators for RBC transfusion (except in emergency situations like major haemorrhage), current indication for transfusion must balance the risks of acute anaemia against the risks of RBC transfusion. Patients differ in their ability to tolerate anaemia depending on their overall clinical condition and whether they have comorbid conditions, such as cardiovascular disease. Establishing the need for RBC transfusion therefore varies and is based on clinical judgement.

Guidelines suggest that transfusion is strongly indicated when the Hb values of critically ill and perioperative patients fall to below 70 g/L, but not justified if Hb values are above 100 g/L. Transfusion for patients with Hb between 70 and 100 g/L should be based on clinical indicators, with Hb between 70 and 90 g/L probably the threshold for managing most critically ill patients who are stable. For patients with significant cardio-respiratory disease, the appropriate Hb concentration on which to base the decision to transfuse has yet to be established.

The authors conclude that "potential RBC shortages and continuing concerns about blood safety mean that guidelines based on sound evidence of clinical effectiveness are urgently required." Although some data is now available that provide some guidance on when transfusion is warranted, no evidence is yet available on when to transfuse critically ill patients with comorbid conditions, such as ischaemic heart disease or severe lung disease.

Blood Rev 2003;17:4:195-208. "Anaemia and red blood cell transfusion in the critically ill patient"

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