title: Comparing biomarkers of traumatic shock: the utility of anion gap, base excess, and serum lactate in the ED.
abstract: 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.
authors.affiliation: Department of Emergency Medicine, Lincoln Medical and Mental Health Center, Bronx, NY.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Caputo
authors.affiliation: Department of Emergency Medicine, Lincoln Medical and Mental Health Center, Bronx, NY.
authors.forename: Marc
authors.initials: M
authors.lastname: Kanter
authors.affiliation: Department of Emergency Medicine, Lincoln Medical and Mental Health Center, Bronx, NY.
authors.forename: Robert
authors.initials: R
authors.lastname: Fraser
authors.affiliation: Department of Surgery, Division of Trauma, Lincoln Medical and Mental Health Center, Bronx, NY.
authors.forename: Ronald
authors.initials: R
authors.lastname: Simon
mesh_terms: D000136:Acid-Base Equilibrium; D000328:Adult; D015415:Biomarkers / Q000097:blood; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000097:blood*; D016014:Linear Models; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D012774:Shock, Traumatic / Q000175:diagnosis*; D017693:Sodium Bicarbonate / Q000097:blood*; D055986:Vital Signs; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019344:Lactic Acid; D017693:Sodium Bicarbonate