Incidence and significance of elevated lactate in the identification of critically ill patients

Background: The frequency and characteristics of patients with critical lactate values (> 4.0 mmol/L) is unknown. Methods: The laboratory database was reviewed for adult patients with non-point of care lactate values over a 6-month period. Results: There were 6914 lactate values, including 625 (9.0 %) critical values. Medical records were reviewed in 100 patients with critical and non-critical lactate values. Patients with critical vs. non-critical values had more metabolic acidosis (n = 70/100 vs. 22/100, p < 0.01), hypotension or tachycardia (n = 62/100 vs. 29/100, p < 0.01), and a higher 1-month mortality (n = 42/100 vs. 7/100, p < 0.01). Few patients (n = 10/100) with a critical value were not in the emergency department or intensive care unit. Conclusions: Critical lactate values are associated with a longer duration of hospitalization and increased mortality. However, the incremental value of critical lactate values was low, as most patients had abnormal vital signs and laboratory parameters. Requiring notification of lactate values > 4.0 mmol/L would be unlikely to augment clinical care.