Beware of transfusion-related confounders in studies on packed red blood cells.

206 AJCC AMERICAN JOURNAL OF CRITICAL CARE, May 2007, Volume 16, No. 3 www.ajcconline.org Beware of Transfusion-Related Confounders in Studies on Packed Red Blood Cells Gould and colleagues provide an excellent review of the limitations of packed cell transfusion in the intensive care unit. I applaud their efforts to painstakingly summarize evidence on a topic of widespread occurrence that is easily overlooked. Although new studies offer data on the judicious use of packed cells in different patient cohorts, one should be wary of potential residual confounders of transfusion-related consequences in these studies. These confounders may be hypothermia secondary to rapid infusion, fluid overload due to improper patient selection and technique, dilutional coagulopathies, infusion technique–associated hemolysis, route of administration, and guideline transfusion bedside compatibility check. Varieties of “lapse errors” exist and these errors vary with the urgency and repetition of situational parameters and potentially can be confounders with higher transfusions. In the developing world, based on my experience at various tertiary care hospitals in India, I have found that critical care units are understaffed and that healthcare staff have poor understanding of the evidence regarding infusion rates, choice of blood product, patient selection, and so on. The need for prospective trials to account for potential confounders and the need for formulation and dissemination of effective transfusion guidelines cannot be overemphasized. NISHITH K. SINGH, MD All India Institute of Medical Sciences New Delhi, India