Prolonged lactate clearance is associated with increased mortality in the surgical intensive care unit.

BACKGROUND: Failure of arterial serum lactate to achieve normal levels has been associated with an increased mortality among medical and trauma patients. At our institution the ability of the patient to normalize arterial serum lactate has been utilized as an end point of resuscitation. In this study, we examine the correlation between length of time to lactate normalization and mortality.
METHODS: The charts of 95 consecutive surgical intensive care unit (SICU) patients requiring hemodynamic monitoring or therapy were reviewed retrospectively. Hemodynamic, demographic, and laboratory data were recorded. Patients were stratified by lactate normalization time, and a subgroup analysis of survivors and nonsurvivors was performed by univariate and multivariate analysis.
RESULTS: Patients not achieving a normal lactate level sustained a 100% hospital mortality rate. Those clearing between 48 and 96 hours sustained a 42.5% mortality rate. Patients normalizing in 24 to 48 hours had a 13.3% mortality rate, and those clearing in less than 24 hours had a mortality rate of 3.9%. Subgroup analysis by survival revealed differences in time to lactate clearance, initial blood pressure, and initial lactate on univariate analysis. On multivariate analysis only time of lactate clearance was found to differ.
CONCLUSIONS: Prolongation of lactate clearance is associated with increasing mortality. Failure of a patient to normalize lactate is associated with 100% mortality. Measurement of arterial serum lactate is a simple and effective predictor of outcome and end point of therapy.