The effect of ethanol on lactate and base deficit as predictors of morbidity and mortality in trauma

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Objective—The objective of this study was to assess the predictive value of lactate and base deficit in determining outcomes in trauma patients who are positive for ethanol. Methods—Retrospective cohort study of patients admitted to a level 1 trauma center between 2005 and 2014. Adult patients who had a serum ethanol, lactate, base deficit, and negative urine drug screen obtained upon presentation were included. Results—Data for 2482 patients were analyzed with 1127 having an elevated lactate and 1092 an elevated base deficit. In these subgroups, patients with a positive serum ethanol had significantly lower 72-hour mortality, overall mortality, and hospital length of stay compared with the negative ethanol group. Abnormal lactate (odds ratio [OR], 2.607; 95% confidence interval [CI], 1.629– 4.173; P = .000) and base deficit (OR, 1.917; 95% CI, 1.183–3.105; P = .008) were determined to be the strongest predictors of mortality in the ethanol-negative patients. Injury Severity Score was found to be the lone predictor of mortality in patients positive for ethanol (OR, 1.104; 95% CI, 1.070–1.138; P=.000). Area under the curve and Youden index analyses supported a relationship between abnormal lactate, base deficit, and mortality in ethanol-positive patients when the serum lactate was greater than 4.45 mmol/L and base deficit was greater than −6.95 mmol/L. Conclusions—Previously established relationships between elevated lactate, base deficit, and outcome do not remain consistent in patients presenting with positive serum ethanol concentrations. Ethanol skews the relationship between lactate, base deficit, and mortality thus resetting the threshold in which lactate and base deficit are associated with increased mortality.