Red blood cell transfusion affects microdialysis-assessed interstitial lactate/pyruvate ratio in critically ill patients with late sepsis

The aim of this study was to explore the effect of red blood cell (RBC) transfusion on microdialysis-assessed interstitial fluid metabolic parameters in septic patients. We conducted a retrospective study of 37 patients with severe sepsis/septic shock requiring transfusion of one to two RBC units. Interstitial fluid metabolic alterations were monitored by a microdialysis catheter inserted in the subcutaneous adipose tissue. Samples were collected before (T0) and after transfusion at two time-points: T1a and T1b; median post-transfusion times of 120 [interquartile range (IQR); 45–180] and 360 (IQR; 285–320) min. Lactate, pyruvate, glycerol and glucose concentrations were measured with a bedside analyzer, and the lactate/pyruvate (LP) ratio was calculated automatically. RBC transfusions decreased the LP ratio from (T0) 18.80 [interquartile range (IQR); 14.85–27.45] to (T1a) 17.80 (IQR; 14.35–25.20; P