This is a single-center, prospective study in 37 septic patients examining the issue of whether red blood cell (RBC) transfusion improves (decreases) the lactate/pyruvate (L/P) ratio, as measured by means of a microdialysis catheter placed in the subcutaneous adipose tissue. Additionally, the authors assessed the influence of leukoreduction and storage time of transfused erythrocytes on the redox status of subcutaneous adipose tissue. The authors found that RBC transfusion significantly decreased the L/P ratio, while leukoreduction and storage time of transfused RBCs had no influence on the LP ratio. The authors concluded that RBC transfusion improves tissue oxygenation and has a beneficial effect on microdialysis-assessed tissue L/P ratio. They recommend that L/P ratio be considered as a transfusion trigger.

However, only 37 patients were included and RBC transfusion was not associated with a decrease in lactate levels. In fact, the only metabolite that really increased its absolute value after RBC transfusion was pyruvate. As a consequence, although no significant variations in the lactate microdialysis sampling were observed, the L/P ratio actually decreased. Because the lactate levels remain unaltered after RBC transfusion, the clinical implications of this study need to be clarified by additional controlled studies.

– Santiago Ramón Leal-Noval