The authors describe an association between increased risk of ARDS in critically ill patients and administration of an average of one additional red blood cell unit. Unfortunately, the quality of the red blood cells used with respect to storage time, additives and leukodepletion, and the administration of other blood products could not be assessed. It is a prospective, but only
observational study without any randomization or control. Therefore, bias and confounding cannot be excluded. However, the study does at least not provide arguments for a liberal transfusion strategy.
– Volker Kretschmer