Prediction of intensive care unit mortality: Interest of serum lactates

Many prognostic indices have been developed to assess clinical status and predict the probability of death in the intensive care unit (ICU) but none have perfect sensitivity or specificity.

To evaluate the prognostic value of admission lactate in patients admitted to ICU.

A cohort, observational, prospective study was carried out in the intensive care unit (ICU) of Mongi Slim Hospital, la Marsa, over 12 months period. Arterial blood lactate (ABL) was measured in ICU admission (H0), then 6 hours (H6), 12 hours (H12), 24 hours (H24) and 48hours (H48) after admission. Prognostic scores were calculated 24 hours after the admission. We also recorded biological data, hemodynamic parameters, and the evolution during the stay in intensive care. Primary endpoint was ICU mortality.

We included 135 patients. The average age was 47.22 ± 16.88 years with a sex-ratio of 1.75. ICU mortality was 48%. The mean ABL at admission was 3.05 ± 2.63 mmol/l, higher in the dead group with a statistically significant difference. Prognostic value of lactate at admission was less powerful than severity indices in this study but remains excellent with an AUC >0, 7 defining « cut-off » values with a good sensitivity and specificity. In multivariate analysis, initial lactate > 2 mmol/l was found to be an independent predictive factor of ICU mortality with an Odd Ratio [IC 95%] =1.16 [1.07 - 3.6]; p=0.04.

Monitoring lactatemia in ICU could allow better identification of patients at high risk of death and the reassessment of therapeutic efficacy.