Admission hyperlactatemia: causes, incidence, and impact on outcome of patients admitted in a general medical intensive care unit

Purpose: The aim of this study was to evaluate the causes, incidence, and impact on outcome of admission hyperlactatemia in patients admitted to a general medical intensive care unit (ICU).

Methods: A retrospective cohort study was done in an 8-bed general ICU of tertiary care hospital over 15 months. Data regarding patient demographics, probable cause of hyperlactatemia, presence of shock, need for organ support, and ICU outcome were recorded. Patients were divided into 2 groups based on admission lactate levels as follows: high lactate (>2 mmol/L) and normal lactate (<2 mmol/L). Patients were compared in terms of need for organ support and ICU mortality.

Results: Admission hyperlactatemia was present in 199 of 653 (30.47%) patients. Shock was the commonest cause, 53.3% patients, followed by respiratory and renal failure in 26 (13.1%) and 16 (8%) patients, respectively. Mean ± SD lactate levels in survivors and nonsurvivors were 1.64 ± 1.56 and 4.77 ± 4.72 mmol/L, respectively (P = .000). Receiver operating characteristic curve for lactate was 0.803 (95% confidence interval [CI], 0.753-0.853). Sensitivity and specificity of lactate (>2 mmol/L) to predict ICU mortality was 74.8% and 77.8%, respectively. Odds ratio for dying in patients with hyperlactatemia was 10.39 (95% CI, 6.378-16.925) with a relative risk of 1.538 (95% CI, 1.374-1.721). On subgroup analysis, in patients without hypotension too, ICU mortality was significantly increased in patients with hyperlactatemia (1.3% vs 6.45%, P = .009).

Conclusions: Admission hyperlactatemia is common in a general ICU and is associated with increased mortality, irrespective of presence of hypotension. Shock was the commonest cause for hyperlactatemia, followed by respiratory and renal failures.