Patients in the intensive care unit (ICU) frequently develop anemia and around 40% of patients receive blood transfusion.1,2 The Transfusion Requirements in Critical Care (TRICC) trial; one of the landmark studies in the ICU; found similar mortality rates when patients were transfused to keep Hb between 70 and 90 g/L compared with more liberal transfusions aiming to keep Hb > 100 g/L.3 A trend toward greater mortality rates was observed with liberal blood transfusions especially in patients older than 55 years and had an Acute Physiology and Chronic Health Evaluation (APACHE) II scores less than 20.
However, in a post hoc analysis, a non-significant trend favoring liberal blood transfusion was observed in patients with ischemic heart disease, although patients with unstable angina and myocardial infarction were excluded at baseline.4
The findings of this study have been recently questioned because RBCs are now leuco-depleted and the impact of RBC storage-related changes may have accordingly changed.5,6 A Cochrane systematic review concluded that more evidence is needed to guide clinicians, especially for patients with cardiac diseases.7,8
A new randomized multicenter pilot study involving six ICUs in the United Kingdom was recently published in Critical Care Medicine journal.9 The authors in this study compared hemoglobin concentration (Hb), RBC use, and patient outcomes when restrictive or liberal blood transfusion strategies are used to treat anemic (Hb ≤ 90 g/L) critically ill patients of age ≥ 55 years requiring ≥ 4 days of mechanical ventilation in the ICU. One hundred patients were randomized to restrictive transfusion strategy targeting 71–90 g/L (n=51) and to liberal transfusion strategy targeting 91–110 g/L (n=49) for 14 days or the remainder of ICU stay, whichever was longest.
No major differences in organ dysfunction, duration of ventilation, infections, or cardiovascular complications were observed during intensive care and hospital follow-up. Mortality at 6 months trended toward higher rates in the liberal group (55%) than in the restrictive group (37%); relative risk was 0.68 (95% CI, 0.44–1.05; p = 0.073). After adjustment using a survival model, the trend remained.
The authors of this study conclude that there was a non-significant trend toward lower mortality with restrictive transfusion strategies. Larger randomized controlled studies are needed to further assess the risk-to-benefit balance of RBC transfusions in sicker older critically ill patients.
1. Walsh TS, Saleh EE. Anaemia during critical illness. Br J Anaesth.
2. Hayden SJ, Albert TJ, Watkins TR, et al. Anemia in critical illness: insights into etiology, consequences, and management. Am J Respir Crit Care Med.
3. Hébert PC, Wells G, Blajchman MA, et al. A multicenter, randomized,controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group. N Engl J Med.