To analyze the prognostic value of lactate levels for day-7 and in-hospital mortality, in septic patients with and without shock. In the period November 2011-December 2016, we enrolled 268 patients, admitted to our High-Dependency Unit with a diagnosis of sepsis. Lactate dosage was performed at ED-HDU admission (T0), after 2 h (T2), 6 h (T6) and 24 h (T24); lactate clearance was calculated at T2 and T6 [T2: ((LAC T0-LAC T2/LAC T0)*100)]; T6: [(LAC T0-LAC T6/LAC T0)*100]. The end-points were day-7 and in-hospital mortality. At every evaluation, the lactate level was higher in patients with shock than in those without (T0 3.8 ± 3.8 vs 2.4 ± 2.1; T6 2.9 ± 3.2 vs 1.6 ± 1.1; T24 3.0 ± 4.4 vs 1.4 ± 0.9 meq/L, all p < 0.001). Among patients with shock, an analysis for repeated measures confirmed a more marked lactate level reduction in survivors compared with non-survivors, both by day-7 and in-hospital mortality (p = 0.057 and p = 0.006). A Kaplan-MeIer analysis confirmed a significantly better day-7 survival in patients with T6 (with shock 86% vs 70%; without shock 93% vs 82, all p < 0.05) and T24 (with shock 86% vs 70%; without shock 93% vs 82, all p < 0.05) lactate ≤ 2 meq/L, compared with patients with higher levels. A T6 lactate clearance > 10% was more frequent among in-hospital survivors in the whole study population (57% vs 39%) and in patients with shock (74% vs 46%, all p < 0.05). Higher lactate levels and decreased clearance were associated with an increased short-term and intermediate-term mortality regardless of the presence of shock.
Keywords: Lactate; Lactate clearance; Prognosis; Septic shock.