Anemia of critical illness – stemming from blood loss, underlying disease, and treatments causing bone marrow suppression – is common in children admitted to the pediatric intensive care unit (PICU). Although red blood cell (RBC) transfusion is a standard treatment for critically ill children, infections, lung injury, hemodynamic compromise, and immunosuppression are possible side effects of this therapy. Despite the potential seriousness of these risks, no multicenter data exists on anemia and transfusions in the PICU. Therefore, a recent study by Bateman et al focused on PICU interventions, such as blood conservation protocols and erythropoietin therapy, to assess the epidemiology of anemia and RBC transfusion in children with extended PICU stays.

To achieve this, the authors designed a multicenter, prospective observational study taking place in 30 PICUs in the United States and Canada. A total of 977 children <18 years of age, were consecutively enrolled from September 8, 2004 through March 29, 2005. The authors note that although this group of children represents only about 20% of PICU admissions, these patients account for a disproportionate use of PICU resources. The authors, therefore, specifically sought to capture outcomes and complications associated with transfusion therapy in this group. In total, 49% of children received one or more RBC transfusions during their stay, with 6% receiving transfusion after discharge.

To examine the effect of transfusion on outcome, the study compared complications that occurred on day three or later in two groups: those transfused on PICU day 1 or day 2 (N=363) and those with no transfusions during their PICU stay (N=494). Children in the transfused group were characterized by (1) higher rates of anemia on PICU admission,(2) higher severity of illness (PRISM III) score, (3) higher daily average blood loss, (4) greater likelihood of shock, (5) more surgical procedures, and (6) greater frequency of cardiovascular disorders. In addition, the transfused group was younger in comparison to the non-transfused group. Logistic regression analysis was used to compare the odds of complications for those who did or did not undergo transfusion. The group receiving transfusion had an increased risk of death and cardiac arrest (odds ratio 20.0; 95% CI 2.6 - 166.7); a higher rate of nosocomial infections (OR 1.9; 95% CI 1.2 - 3.0); and more cardiac and respiratory dysfunction (OR 2.1; 95% CI 1.5 - 3.0). Also, children receiving transfusion experienced longer overall stays in the PICU (9.3 vs. 7.5 days), and 12 of 15 deaths occurred in children who received four or more transfusions. No further details about the deaths were provided. However, it raises the question as to whether transfusion is a marker for rather than an initiator of poor outcome.

Since transfusions (74%) predominantly occurred within the first 48 hours of the PICU stay, this study provides evidence against the efficacy of erythropoietin administration and emphasizes the need for a greater focus on blood loss prevention. Indeed, the authors emphasize that blood loss from blood draws accounted for the majority of total blood loss occurring during the PICU stay in all age groups. The authors also emphasize that anemia, especially those with hemoglobin levels <5 g/dL, represents an independent risk factor for death in children. They suggest, as have other studies, that a reasonable transfusion threshold be <7 g/dL of hemoglobin in otherwise stable children. Clinical variability and severity such as the presence of shock and cardiovascular disease may require a higher transfusion threshold. Importantly, the high incidence of death among children who received four or more transfusions warrants further studies to establish effective guidelines for transfusion strategies.

Bateman ST, Lacroix J, Boven K, Forbes P, Barton R, Thomas NJ, Jacobs B, Markovitz B, Goldstein B, Hanson JH, Li HA, Randolph AG; Pediatric Acute Lung Injury and Sepsis Investigators Network. Anemia, blood loss, and blood transfusions in North American children in the intensive care unit. Am J Respir Crit Care Med. 2008 Jul 1;178(1):26-33.

NAAC Expert Commentary:
One of the major uncertainties in the field of transfusion medicine emphasized during this decade has been how to optimize the use of transfusion therapy to maximize clinical utility and minimize adverse impact. The study by Bateman et al places further scrutiny on this dilemma. They note that although anemia is common in PICU patients, little is known about its etiology and the use and efficacy of transfusion therapy. The authors add that the majority of blood loss in PICU patients is due to phlebotomy. They also note that several complications, including death, cardiac arrest, and nosocomial infections are more common in the transfused group. However, this study is not designed to prove whether transfusion causes these complications or whether use of transfusion, especially multiple units, is a marker for sicker children. It is clear, based on the information in this paper, and until further studies are forthcoming, that efforts should be made to reduce blood draws to a minimum and to use blood transfusion therapy judiciously.

Last Updated: January 7, 2009