The purpose of this study was to determine the utility of an initial serum lactate measurement for identifying high risk of death in patients admitted to the ICU.
In a cohort study at a tertiary-care nontrauma medical–surgical ICU, we included all ICU admissions (May 2007 to February 2008) from a prospectively collected ICU database. Patients' gender, age, admission physiologic measurements, lactic acid, and APACHE IV score were noted. Outcome was acute phase death (death within 3 days of admission) and inhospital death. Outcome was stratified by the initial serum lactic acid level in three groups: low, 0.0 to 2.0; intermediate, 2.1 to 3.9; high, 4.0 mmol/l or above.
Total of 882 patients were included in the study, acute phase death rates were 2.5%, in the low group, 5.1% in intermediate group and 8.1% in the high group, whereas inhospital mortality rates were 13.9%, 28.6%, and 38.7%, respectively. Acute-phase deaths and inhospital deaths increased linearly with lactate. An initial lactate ≥ 4.0 mmol/l was associated with at least a threefold higher odds ratio for both acute-phase deaths 2.8 (95% CI = 1.1 to 7.3) and inhospital mortality 3.4 (95% CI = 2.0 to 5.8).
An initial lactate ≥ 4.0 mmol/l substantially increases the probability of acute-phase death and inhospital mortality in critically ill patients.