Blood Banks Under Siege

Blood Banks Under Siege

CHEST Blood Banks Under Siege To the Editor: The article1 by Netzer et al in the October issue of CHEST asserts, essentially, that there is something ...

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CHEST Blood Banks Under Siege To the Editor: The article1 by Netzer et al in the October issue of CHEST asserts, essentially, that there is something seriously wrong with the principal product of our blood banks when transfused in acute lung injury (ALI)/ARDS patients. The product has indeed been degraded by its general availability as packed RBCs only and, additionally, there is an imputed problem with the buffy coat itself as a possible cause of ALI/ARDS. This in turn is driving the questionable necessity of leukoreduction. The clear statistical association between mortality and number of units transfused, both from this article and other sources, has driven the product unjustly into pariah status among therapeutic biologics. “Transfusion avoidance” strategies are even under study to see “how low can you go” before anemia impairs recovery. “Fake blood” is under development. At risk of belaboring the obvious, the number of packed RBCs transfused is more likely a measure of the seriousness of the patient’s condition. The article adds anxiety and confusion over the acceptability of anemia in resuscitation. The authors noted their study was inadequate as to a relationship of transfusion before the development of ALI/ARDS. Yet, they go on to state that the deleterious effects of transfusion were exerted “predominately” after the onset of ALI/ ARDS. This statement is intrinsically contradictory. The large fault with the article is that the design of the study provided for recruitment of patients already with ALI/ARDs. The same fault nearly destroyed the value of the large, recently reported Fluids and Catheter Treatment Trials2 by the National Institutes of Health, which demonstrated the definite, albeit narrow, value of a restricted fluids vs a liberal fluids strategy, also in already diagnosed ALI/ARDS cases. Patients with ALI/ARDS are seriously fluid overloaded and edematous as shown from an overweight condition calculated by the National Heart Lung and Blood Institute itself.3 Excessive parenteral isotonic fluid dilutes the extracellular fluid space and drives down the hemoglobin concentration. The nearly universal ICU anemia is thus factitious, and is the reason for the very high incidence of transfusion. Similarly, the anemia of the ICU that affects nearly all of the patients there more than 3 or 4 days is dilutional. Rather than concentrating on restriction of blood transfusion in the ICU patient, concentration on avoiding excessive IV fluids will do much to prevent or improve ALI/ARDS and the associated dilutional anemia. There is no “absence of (. . . physiologic . . .) evidence” that blood transfusion should be given when by conventional standards the patient’s anemia threatens his recovery. William S. Lyons, MD INOVA Fairfax Fairfax, VA The author has no conflict of interest to disclose. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml). 214

Correspondence

Correspondence to: William S. Lyons, MD, INOVA Fairfax, 3300 Gallows Rd, Fairfax, VA 22042; e-mail: [email protected] DOI: 10.1378/chest.07-3067

References 1 Netzer G, Shah C, Iwashyna TJ, et al. Association of RBC transfusion with mortality in patients with acute lung injury. Chest 2007; 132:1116 –1123 2 National Heart, Lung, and Blood Institute ARDS Clinical Trials Network. N Engl J Med 2006; 354:2564 –2575 3 Writing Committee of the Acute Respiratory Disease Network. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory disease syndrome. N Engl J Med 2000; 342:1301– 1308

Response To the Editor: We thank Dr. Lyons for his consideration of our study.1 We are in agreement with him that a general concern of any observational study of therapy is the potential for confounding by indication (ie, that blood transfusion is reflective of severity of illness and that increased mortality is associated with this rather than with the transfusion itself). For this reason, we took great care in our analysis to account for this by multiple methods (Tables 2 and 3 in our study), all of which resulted in consistent results.1 As Dr. Lyons points out, like the Fluid and Catheter Treatment Trial (FACTT), our study addresses the care of patients with established acute lung injury (ALI)/ARDS. These studies were not designed to address the care of patients before the development of ALI. It should be noted that in a study by Gong et al2 transfusion before the development of ALI/ARDS was associated with both an increased risk of developing ALI/ARDS as well as mortality from it. While the FACTT found that patients with ALI/ARDS are in significant positive fluid balance, we disagree with the assertion that this causes a “factitious” anemia seen in the ICU. Anemia in critically ill patients is common, and its causes are multifactorial, including decreased production of erythrocytes due to low erythropoietin production and bone marrow suppression, decreased RBC survival, and ongoing blood loss from phlebotomy (approximately 40 mL/d), procedures, and coagulopathy.3 It is our hope that future randomized clinical trials will help us to better discern the optimal transfusion strategy in patients with ALI/ARDS. Until this occurs, our study validated the results of prior observational studies as well as the landmark randomized clinical trial, the Transfusion Requirements in Critical Care Investigators (TRICC) trial.4 As Drs. Schorr and Corwin point out in their editorial,5 like all ICU interventions, transfusion is associated with risks and benefits that must be Correspondence