Cumulative lactate load correlates with cumulative Sequential Organ Failure Assessment score and survival in intensive care unit patients

Background

Changes in lactate levels are used as a prognostic marker in critically ill patients. However, the relation between the time course of arterial blood lactate clearance and important outcome parameters such as ICU length of stay (LOS), incidence of organ failure and survival rate has not been established.

Methods

Case records from all ICU patients admitted between 2002 and 2004 were retrospectively identified in the ICU database. The Sequential Organ Failure Assessment (SOFA) score was calculated daily to assess the time course of organ failure. All lactate levels were extracted and the total cumulative lactate load (area under the curve above the upper normal level of 2.2 mmol/l; cum-lactate), and total cumulative SOFA score (cum-SOFA) were calculated and related to ICU LOS and final hospital survival. Values are the median (interquartile range).

Results

Observations in 1,711 ICU admissions were analyzed, age was 69 (57–77) years, cum-lactate was 420 (94–419 min· mmol/l) and cum-SOFA was 11 (4–38). Cum-SOFA was higher in patients with hyperlactatemia (cum-lactate > 0) during the ICU stay (n = 782; 24 (7–71)) than in those without (5 (3–20); P < 0.001). Cum-SOFA correlated with cum-lactate and with ICU LOS, and cum-lactate correlated with ICU LOS (all P < 0.001). In patients who died in the hospital (n = 329), cum-lactate (1,180 (203–3,427) min· mmol/l) and cum-SOFA (30 (10–95)) were higher than in hospital survivors (n = 1,382; 298 (73–1,154) min· mmol/l, and 22 (5–67); both P < 0.001). In emergency admissions, cum-lactate (484 (113–2,031)) and cum-SOFA (27 (8–78)) were higher than in planned admissions (131 (37–454)) and (4 (3–28); both P < 0.001), respectively.

Conclusion

In ICU patients, the cumulative area under the lactate curve correlates with the ICU LOS, cumulative SOFA score, and inhospital mortality. The prognostic value of cum-lactate requires prospective evaluation.