Prognostic value of admission serum lactate concentrations in intensive care unit patients.
BACKGROUND
Although blood lactate concentrations have an established prognostic value in circulatory shock or after cardiac arrest, their relationship with morbidity and length of stay in general intensive care unit (ICU) populations has not been well defined.


METHODS
This study included all 433 patients (246 surgical and 187 medical) consecutively admitted to the Department of medico-surgical intensive care. Hyperlactataemia was defined as a serum lactate concentration > or = 2 mEq/l.


RESULTS
On admission, 195 patients (45%) had hyperlactataemia. Hyperlactataemic patients had higher Acute Physiology and Chronic Health Evaluation (APACHE) II (13.3 +/- 6.9 vs 10.0 +/- 5.2) and Sequential Organ Failure Assessment (SOFA) (5.3 +/- 3.3 vs 3.3 +/- 2.3) scores than patients with normal lactate concentrations (both p < 0.01). There was no overall difference in length of ICU stay (LOS) between the two groups but survivors in the hyperlactataemic group had a longer LOS than survivors in the normal lactate group, whereas hyperlactataemic non-survivors had a shorter LOS than normal lactate non-survivors. Mortality was 9% in patients with normal lactate concentrations and 23% in hyperlactataemic patients. The mortality rate increased with increasing lactate concentrations, from 17% in patients with lactate concentrations from 2-4 mEq/l to 64% in those with concentrations more than 8 mEq/l. Non-survivors had higher lactate concentrations than survivors on admission, and after 24 and 48 hours. Risk factors for developing hyperlactataemia that were present on admission were SOFA score > 5, mean arterial blood pressure less than 70 mmHg, blood sugar greater than 110 mg/dl, and current use of vasopressors.


CONCLUSIONS
Our study documents a direct relationship between the serum lactate level on ICU admission and not only the risk of death in ICU but also the length of ICU stay. Hyperlactataemic survivors have a longer LOS and non-survivors a shorter LOS than normal lactate survivors and non-survivors, respectively.
Soliman
H M
HM
Department of Intensive Care, Erasme Hospital, Université Libre de Bruxelles, Belgium.
Vincent
J-L
JL
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003422:Critical Care; D016638:Critical Illness / Q000401:mortality*; D003955:Diagnostic Tests, Routine; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis
D019344:Lactic Acid