Serum lactate and base deficit as predictors of mortality and morbidity

Objectives: To determine whether lactate levels and base deficits in critically ill surgical intensive care unit (SICU) patients correlate and whether either measure is a significant indicator of mortality and morbidity. Methods: A review was made of 137 SICU patients who had serial lactate and blood gas measurements. Patients were stratified by absolute lactate and base deficit values as well as time to lactate clearance. Results: Initial and 24-hour lactate level was significantly elevated in nonsurvivors versus survivors (P = 0.002). Initial base deficit was not significantly different; 24-hour base deficit did achieve statistical significance (P = 0.02). Subgroup analysis among trauma patients (n = 36) and major abdominal surgery (n = 101) confirmed the significant correlation between lactate levels and survival. There was poor correlation between initial and 24-hour lactate and base deficit among all patients (r = -0.3 and -0.5). Mortality if lactate normalized within 24 hours was 10%, compared with 24% for >48 hours and 67% if lactate failed to normalize. Physical status at discharge was related to initial lactate (P = 0.05), as well as to lactate clearance time (P = 0.01). Conclusions: Elevated initial and 24-hour lactate levels are significantly correlated with mortality and appear to be superior to corresponding base deficit levels. Lactate clearance time may be used to predict mortality and is associated with outcome at discharge. Initial base deficit is a poor predictor of mortality and did not correlate with lactate levels except in trauma nonsurvivors. In addition to being used as an endpoint for resuscitation, lactate may be predictive of certain morbidities and patient outcome at discharge.