Kopterides P et al. – Tissue oxygenation is affected by red blood cell (RBC) transfusion in critically ill septic patients. Monitoring of tissue lactate/pyruvate (LP) ratio by microdialysis may represent a useful method for individual clinical management.Methods
- The authors 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<0.05) and (T1b) 17.90 (IQR; 14.45–22.75; P<0.001), while there was also significant interindividual variation.
- Post–transfusion LP ratio changes at T1a [r=–0.42; 95 % confidence interval (CI),–0.66 to–0.098; P=0.01] and T1b (r=–0.68; 95 % [CI],–0.82 to–0.44; P<0.001) were significantly correlated with the pre–transfusion LP ratio, but not with baseline demographic characteristics, vital signs, severity scores, hemoglobin level and blood lactate.
- RBC storage time and leukocyte reduction had no influence on the tissue metabolic response to transfusion.