Elevated adipose tissue lactate to pyruvate (L/P) ratio predicts poor outcome in critically ill patients with septic shock: a microdialysis study.

BACKGROUND: Sepsis is a disease affecting tissue metabolism; in vivo microdialysis (MD) is a bedside technique enabling researchers to monitor tissue metabolic changes. We conducted this study aiming to evaluate the relationship between lactate to pyruvate (L/P) ratio, a sensitive marker of tissue oxygenation and perfusion, and mortality in critically ill septic patients. METHODS: We enrolled 105 patients with septic shock hospitalized in the mixed intensive care unit of a tertiary hospital. A MD catheter was inserted in the subcutaneous adipose tissue of the upper thigh and interstitial fluid samples were collected and analyzed for glucose, lactate, pyruvate, and glycerol. RESULTS: Multivariate regression analysis showed that among variables registered on day 1, APACHE II and SOFA scores, blood lactate and microdialysis-assessed tissue L/P ratio were independently associated with 28-day mortality. Even in patients with normal ( 25) L/P ratios showed that the latter survived significantly less (P=0.02; log-rank test). CONCLUSION: Elevated adipose tissue L/P ratio is associated with poor outcome in critically ill patients with septic shock. Microdialysis deserves to be further studied as a research tool in the multi-modal monitoring of septic critically ill patients.