Arterial Blood Lactate Concentrations as a Prognostic Predictor in Critically Ill Patients: in Comparison with APACHE II Scores

Park, Won Sun; Koh, Shin Ok; Kim, Jae Hyung; Na, Sung Won

Abstract

BACKGROUND: Disordered lactate metabolism which is due to tissue hypoxia and hypoperfusion is frequently encountered in critically ill patients. These patients suffer from a high hospital mortality rate and are at great risk of developing multiple organ failure. The present study was designed to evaluate the prognostic value of blood lactate as a determinant of mortality in comparison with the APACHE II score.
METHODS
29 adult ICU patients participated in this study. Blood lactate concentrations, arterial blood gas analysis, hemodynamic data and APACHE II scores were collected on the first and last days of ICU stay. These data were compared between survivor and non-survivor groups.
RESULTS
On the day of admission, blood lactate concentrations and APACHE II scores of non-survivors were 48.5 +/- 27.0 mg/dl and 18.5 +/- 5.9, while those of survivors were 23.7 +/- 12.9 mg/dl and 6.7 3.1. On the day of discharge, arterial blood lactate concentrations and APACHE II scores of non-survivors were 143.2 +/- 54.0 mg/dl and 28.2 +/- 6.0, while those of survivors were 14.9 +/- 7.1 mg/dl and 4.7 +/- 2.2. There was a significant positive correlation between high arterial blood lactate concentration and fatal outcome in critically-ill patients. There was also a significant positive correlation between arterial blood lactate concentration and APACHE II score. Furthermore, decreases in arterial blood lactate levels during the course of ICU stay may indicate a favorable outcome. The mortality increased abruptly in critically-ill patients with an initial arterial blood lactate concentration higher than 40 mg/dl.
CONCLUSIONS
The result shows that arterial blood lactate concentration can serve as a reliable prognostic predictor and clinical guide to therapy in critically ill patients.