Arterial lactate level is associated with mortality rate in unscheduled surgical intensive care admissions

Background: Lactate is a widely used biomarker for patients with conditions such as infection or trauma. The value of lactate level in risk stratification is rarely investigated for patients admitted to the surgical Intensive Care Unit (ICU), regardless of diagnosis.Purposes: This study examines whether arterial lactate levels at the approximate time of admission can predict short-term mortality in all unscheduled surgical ICU patients.Materials and Methods: A retrospective cohort study of all unscheduled surgical ICU admissions from July 2010 to June 2013 was conducted. Patients were stratified into low (<2.0 mmol/L), intermediate (2.0–3.9 mmol/L), and high (≥4.0 mmol/L) lactate groups according to initial lactate measurements. The primary endpoint was 28-day mortality.Results: Of 1404 eligible admissions, 163 (11.6%) of them died within 28 days. Admission lactate levels were significantly higher in nonsurvivors than in survivors (P < 0.001). Multiple regression analysis showed that both intermediate and high lactate levels were independent risk factors for mortality. Patients with a high lactate level had an odds ratio (OR) of 1.81 (95% confidence interval [CI] 1.12–2.91; P = 0.015) relative to patients with a low lactate level. Patients with an intermediate lactate level had an OR of 1.73 (95% CI 1.07–2.79; P = 0.025) relative to patients with a low lactate level. Other independent predictors of mortality included Acute Physiology and Chronic Health Evaluation II score, existence of malignancy, and thrombocytopenia.Conclusion: An admission arterial lactate level of 2.0 mmol/L or higher at the time of ICU admission can be used to identify high-risk surgical patients