Comparing biomarkers of traumatic shock: the utility of anion gap, base excess, and serum lactate in the ED

Background: Biomarkers such as serum lactate, anion gap (AG), and base excess (BE) have been shown to be of use in determining shock in patients with seemingly normal vital signs. We seek to determine if these biomarkers can be used interchangeably in patients with trauma in the emergency setting based on their test characteristics and correlation to each other. Methods: A prospective observational cohort study was undertaken at an urban level 1 trauma center. Baseline vital signs, point-of-care BE, AG, and serum lactate were recorded in all patients who presented for trauma. Correlation was determined by linear regression model. Overall test characteristics and relative risk were calculated. Results: One hundred patients were enrolled. The median age was 30 years (interquartile range, 24-42 years), and 89% were male. Fifty-three percent of injuries were blunt trauma. Pearson correlation of serum lactate to BE was -0.81 (r(2) = 0.66; 95% confidence interval [CI], 0.53-0.75; P<.001), that of BE to AG was -0.71 (r(2) = 0.5; 95% CI, -0.80 to -0.57; P < .01), and that for serum lactate to AG was 0.71 (r(2) = 0.5; 95% CI, 0.57-0.80; P < .01). Conclusions: This study demonstrates that the biomarkers have similar test characteristics which may make them interchangeable as indicators for the presence of occult shock in patients with trauma. Lactate and BE correlate well with each other; however, AG was not as strongly correlated with either. (C) 2015 Elsevier Inc. All rights reserved.