[Prognostic value of lactate clearance in the first 6 hours of intensive medicine course]. / Valor pronóstico del aclaramiento de lactato en las primeras 6 h de evolución en medicina intensiva.

OBJECTIVE: Analyze the clinical usefulness of lactate clearance (CL6) immediately after admission to the intensive care unit (ICU) in the first 6 hours. SETTING: Surgical-ICU. Centro de Asistencia del Síndicato Médico of Uruguay. DESIGN: Prospective, analytic and observational study performed between December 1, 2004 and March 31, 2006 in patients over 18 years whose arterial lactate level is higher than 2 mEq/l on admission to the ICU. Lactate clearance (CL6) was defined as the quotient between admissions (L0) minus the six hour lactate level (L6) divided by the admission lactate level. Sensitivity, specificity, positive and negative prognostic value for different CL6 cutoff were analyzed. The optimal CL6 was considered as the cutoff with the highest sum of sensitivity plus specificity. RESULTS: One hundred and eight patients were included; 64 patients died (mortality intra-ICU 59.3%). ICU mortality related variables, identified by Cox regression analysis, were CL6 (HR=0.458; CI 95%, 0.239-0.876), L0 (HR=1.16; CI 95%, 1.033-1.303) and SAPSII (HR=1.019; CI 95%, 1.006-1.034). A CL6 equal to or lower than 0.4 was considered as optimal cutoff with a positive prognostic value of 74% and negative prognostic value of 61%. It was also associated with lower survival adjusted by the SAPSII value and L0. CONCLUSIONS: In critically ill surgical patients, whose CL6 on admission was over 2 mEq/l, lactate clearance in the first six hours could be useful to predict the ICU outcome.