title: Association between blood lactate levels, Sequential Organ Failure Assessment subscores, and 28-day mortality during early and late intensive care unit stay: a retrospective observational study.
abstract: OBJECTIVE
  To evaluate whether the level and duration of increased blood lactate levels are associated with daily Sequential Organ Failure Assessment (SOFA) scores and organ subscores and to evaluate these associations during the early and late phases of the intensive care unit stay.
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  Mixed intensive care unit of a university hospital.
  
  
  METHODS
  134 heterogeneous intensive care unit patients.
  
  
  METHODS
  None.
  
  
  RESULTS
  We calculated the area under the lactate curve above 2.0 mmol/L (lactateAUC>2). Daily SOFA scores were collected during the first 28 days of intensive care unit stay to calculate initial (day 1), maximal, total and mean scores. Daily lactateAUC>2 values were related to both daily SOFA scores and organ subscores using mixed-model analysis of variance. This was also done separately during the early (<2.75 days) and late (>2.75 days) phase of the intensive care unit stay.Compared with normolactatemic patients (n = 78), all median SOFA variables were higher in patients with hyperlactatemia (n = 56) (initial SOFA: 9 [interquartile range 4-12] vs. 4 [2-7]; maximal SOFA: 10 [5-13] vs. 5 [2-9]; total SOFA: 28 [10-70] vs. 9 [3-41]; mean SOFA: 7 [4-10] vs. 4 [2-6], all p < .001). The overall relationship between daily lactateAUC>2 and daily SOFA was an increase of 0.62 SOFA-points per 1 day.mmol/L of lactateAUC>2 (95% confidence interval, 0.41-0.81, p < .00001). During early intensive care unit stay, the relationship between lactateAUC>2 and SOFA was 1.01 (95% confidence interval, 0.53-1.50, p < .0005), and during late intensive care unit stay, this was reduced to 0.50 (95% confidence interval, 0.28-0.72, p < .0005). Respiratory (0.30, 0.22-0.38, p < .001) and coagulation (0.13, 0.09-0.18, p < .001) subscores were most strongly associated with lactateAUC>2.
  
  
  CONCLUSIONS
  Blood lactate levels were strongly related to SOFA scores. This relationship was stronger during the early phase of intensive care unit stay, which provides additional indirect support for early resuscitation to prevent organ failure. The results confirm that hyperlactatemia can be considered as a warning signal for organ failure.
authors.affiliation: Department of Intensive Care, Erasmus MC University Hospital Rotterdam, The Netherlands.
authors.forename: Tim C
authors.initials: TC
authors.lastname: Jansen
authors.forename: Jasper
authors.initials: J
authors.lastname: van Bommel
authors.forename: Roger
authors.initials: R
authors.lastname: Woodward
authors.forename: Paul G H
authors.initials: PG
authors.lastname: Mulder
authors.forename: Jan
authors.initials: J
authors.lastname: Bakker
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D042241:Early Diagnosis; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009102:Multiple Organ Failure / Q000401:mortality / Q000517:prevention & control*; D009426:Netherlands / Q000453:epidemiology; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016019:Survival Analysis
chemical_list: D015415:Biomarkers; D019344:Lactic Acid