Base excess and arterial lactate as early prognostic markers in severe sepsis patients

Introduction

The development of therapeutic goals depends on accurate evaluation of the supply of oxygen to organs and tissues. But tissular oxygenation and perfusion are difficult to measure and have a labile behavior. This study has an objective to evaluate the clinical utility of base excess (BE) and arterial lactate (AL) as early markers of morbidity and mortality in patients with severe sepsis assisted in the emergency department.

Methods

A contemporary cohort study involving adult patients with severe sepsis attending the emergency department in a tertiary hospital. We use the criteria of the SCCM/ACCP consensus conference to standardize the diagnosis of severe sepsis.

Results

A total 203 patients were enrolled, with mean age 74 ± 13.6 years; 51.7% of these patients were male. The hospital mortality rate was 65%. The mean AL was 3.0 ± 2.2 and the mean BE was -5.8 ± 6.8. Comparing survivors and non-survivors, the discriminative variables were age, APACHE II score and SOFA score, number of organ dysfunctions, AL ≥ 5 mmol/l, BE ≤ -4 mmol/l, lungs as site of infection, plus systolic and mean arterial pressure. The correlation between AL and BE using Pearson's coefficient of correlation showed an R² value of 0.40 (P < 0.0001). The Kaplan–Meier curve for AL ≥ 5 mmol/l was discriminative (log rank 0.002), but the same did not occur with BE ≤ -4 mmol/l (log rank 0.126). Logistic regression has shown that the variables considered as independent risk factors were age (P < 0.0001; OR 1.059 and 95% CI 1.028–1.091) and the number of organic dysfunctions (P < 0.0001; OR 2.115 and 95% CI 1.448–3.090).

Conclusion

AL ≥ 5 mmol/l and BE ≤ -4 mmol/l could discriminate survivors from non-survivors. Only the Kaplan–Meier curve from AL has reached statistic significance and the correlation between AL and BE was weak. Neither of these variables (AL and BE) were considered independent risk factors for death in this population of severe sepsis patients.