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

Intensive Care Medicine, 07/17/2012

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.

Results

  • 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.

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