This large study identified a nearly linear relationship between lactate level and mortality.

To analyze the relationship between blood lactate levels and mortality in patients with suspected infection, researchers reviewed charts from 2596 patients who were admitted from the emergency department (ED) with suspected infection (inferred from administration of antibiotics in the ED) and who had blood lactate levels measured in the ED.

Overall in-hospital mortality was 14.4%, and the median initial lactate level was 2.1 mmol/L. The initial lactate level was >4 mmol/L in 17.6% of patients. Mortality rose continuously across a continuum of incremental lactate elevations, ranging from 6% in patients with lactate levels <1.0 mmol/L to 39% in patients with levels of 19 to 20 mmol/L.

Comment: We can draw two important conclusions from this study. First, patients with suspected infection who have lactate levels <4 mmol/L still are at risk of dying, so physicians should not base their evaluation of illness severity and patient risk solely on lactate level. Second, mortality risk increases with increasing lactate level, making resuscitation of patients with higher levels a priority.

Source: Journal Watch Emergency Medicine