A study on serum lactate levels as a prognostic marker of sepsis

Abstract

Background: Sepsis and septic shock are a leading cause of mortality worldwide. An elevated serum lactate level is an early maker of sepsis induced hypoperfusion. This study evaluates the clinical utility of lactate clearance and serum lactate levels in sepsis as a prognostic marker in these patients.Materials and Methods: An observational study was conducted over a period of 1 year and 109 ICU patients diagnosed with sepsis or septic shock were included. Mortality analysis was done using Chi- square test and unpaired t test. ‘p’ value < 0.05 was considered as statistically significant. Correlation coefficients were calculated for comparison of blood lactate levels with mean arterial pressure, serum creatinine and heart rate. The area under the receiver operating characteristic curve (AUROC) analysis was carried out for lactate levels at various time intervals, lactate/albumin ratio and lactate clearance to predict in house mortality; with AUROC closer to 1.0 being significant.Results: Out of the 109 patieents studied, significant mortality was an associated with higher blood lactate levels on admission (p<0.05) as well as those taken at 6 hrs, 12hrs and 24 hrs after admission to intensive care unit (p<0.05). The decreased clearance of lactate and higher lactate/serum albumin ratio was associated with significant mortality (p<0.05). The blood lactate was found to have a positive correlation with heart rate, respiratory rate and serum creatinine and a negative correlation with mean arterial pressure. AUROC for lactate at 24 hrs post admission to ICU were superior as compared to those at 12hrs, 6 hrs post admission and that measured at the time of admission. AUC for lactate as tool for predicting mortality was found to be superior as compared to that of AUC (95%CI) of lactate clearance which was 0.68 (0.17-0.22) and lactate: albumin ratio 0.66 (1.9-2.48)Conclusion: Successive lactate measurement serves as a better prognostic tool in patients with sepsis and septic shock as compared to initial lactate clearance and lactate: albumin ratio. Thus serum lactate levels could be used in patient assessment, for stratification of sepsis patients in intensive care units and in goal directed therapy for improving outcomes and for predicting prognosis.