Base excess is an accurate predictor of elevated lactate in ED septic patients

Background: Prior studies showed that lactate is a useful marker in sepsis. However, lactate is often not routinely drawn or rapidly available in the emergency department (ED).

Objective: The study aimed to determine if base excess (BE), widely and rapidly available in the ED, could be used as a surrogate marker for elevated lactate in ED septic patients.

Methods: This was a prospective and observational cohort study. From March 2009 to March 2010, consecutive patients 18 years or older who presented to the ED with a suspected severe sepsis were enrolled in the study. Lactate and BE measurements were performed. We defined, a priori, a clinically significant lactate to be greater than 3 mmol/L and BE less than -4 mmol/L.

Results: A total of 224 patients were enrolled in the study. The average BE was -4.5 mmol/L (SD, 4.9) and the average lactate was 3.5 mmol/L (SD, 2.9). The sensitivity of a BE less than -4 mmol/L in predicting elevated lactate greater than 3 mmol/L was 91.1% (95% confidence interval, 85.5%-96.6%) and the specificity was 88.6% (95% confidence interval, 83.0%-94.2%). The area under the curve was 0.95.

Conclusion: Base excess is an accurate marker for the prediction of elevated lactate in the ED. The measurement of BE, obtained in a few minutes in the ED, provides a secure and quick method, similar to the electrocardiogram at triage for patients with chest pain, to determine the patients with sepsis who need an early aggressive resuscitation.