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).

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.

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.

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.

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.