Acidosis predicts mortality independently from hyperlactatemia in patients with sepsis

RATIONALE AND OBJECTIVES: Acidosis and hyperlactatemia predict outcome in critically ill patients. We assessed BE and pH for risk prediction capabilities in a sub-group of septic patients in the MIMIC-III database. METHODS: Associations with mortality were assessed by logistic regression analysis in 5586 septic patients. Baseline parameters, lactate concentrations, pH, and BE were analyzed at baseline and after 6 hours. MEASUREMENTS AND MAIN RESULTS: We combined acidosis (defined as either BE 2.3 mmol/L; n = 2125) and high-risk (both acidosis and lactate >2.3 mmol/L; n = 1167). Mortality was 14%, 20% and 38% (p 2.3 mmol/L (AUC 0.60 95%CI 0.58-0.62; p<0.001) alone. Hyperlactatemia alone was only moderately predictive for acidosis (AUC 0.60 95%CI 0.59-0.62). CONCLUSIONS: Acidosis and hyperlactatemia can occur independently to a certain degree. Combining acidosis and hyperlactatemia in a model yielded higher predictiveness for ICU-mortality. Septic patients with acidosis should be treated even more aggressively in the future.