ORIGINAL ARTICLE Prehospital Serum Lactate as a Predictor of Outcomes in Trauma Patients: A Retrospective Observational Study Francis Guyette, MD, Brian Suffoletto, MD, Jose-Luis Castillo, MD, Jorge Quintero, MD, Clifton Callaway, MD, PhD, and Juan-Carlos Puyana, MD Background: Lactate is associated with morbidity and mortality; however, the value of prehospital lactate (pLA) is unknown. Our objective was to determine whether pLA improves identification of mortality and morbidity independent of vital signs. Methods: We measured pLA in 1,168 patients transported by rotorcraft to a Level I trauma center over 18 months. The primary outcome was in-hospital mortality; secondary outcomes were emergent surgery and multiple organ dysfunction syndrome (MODS). Covariates include age, sex, prehospital vital signs, and mental status. We created multivariable logistic regression models and tested them for interaction terms and goodness of fit. Cutoff values were established for reporting operating characteristics using shock (defined as shock index 0.8, heart rate 110, and systolic blood pressure 100), tachypnea (RR 30), and altered sensorium (Glasgow Coma Scale score 15). Results: In-hospital mortality was 5.6%, 7.4% required surgery and 5.7% developed MODS. Median lactate was 2.4 mmol/L. Lactate was associated with mortality (odds ratio [OR], 1.23; p  0.0001), surgery (OR, 1.13; p  0.001), and MODS (OR, 1.14; p  0.0001). Inclusion of pLA into a logistic model significantly improved the area under the receiver operator curves from 0.85 to 0.89 for death (p  0.001), 0.68 to 0.71 for surgery (p = 0.02), and 0.78 to 0.81 for MODS (p = 0.002). When a threshold lactate value of 2 mmol/L was added to a predictive model of shock, respiratory distress, or altered sensorium, it improved sensitivity from 88% to 97% for death, 64% to 86% for surgery, and 94% to 99% for MODS. Conclusion: The pLA measurements improve prediction of mortality, sur- gery, and MODS. Lactate may improve the identification of patients who require monitoring, resources, and resuscitation. Key Words: Prehospital, Lactate, Trauma. (J Trauma. 2011;70: 782–786) T raditional trauma triage uses physiologic variables, in- cluding vital signs, which often do not predict need for surgical resources or outcomes. 1,2 Blood pressure and heart rate may change later in shock when compensatory mechanisms fail in hemorrhagic shock. Compensated shock is not easily recog- nizable by prehospital providers. 2– 6 Delayed identification of hypoperfusion may lead to triage of some patients away from specialized trauma centers and to inadequate or delayed resus- citation, which is strongly associated with increase in infection, multiple organ dysfunction (MOD), and mortality. 3,7,8 Serum lactate is a byproduct of anaerobic metabolism, is a circulating biomarker of organ oxygen supply/demand mismatch, and is directly related to mortality in patients with sepsis, myocardial infarction, and trauma. 9,10 Trends in serum lactate levels can also monitor the effectiveness of resuscita- tion, even in patients with normal vital signs. 10,11 Currently, technological advances have led to the production of hand- held, point of care (POC) lactate analyzers that produce fast, reliable, and valid measurements. 12 Use of POC lactate is now feasible in the out-of-hospital setting, but the additional value of prehospital lactate (pLA) for predicting in-hospital outcomes is unknown. Importance If increased pLA identifies patients who go on to have clinically significant outcomes after trauma, then it may assist prehospital triage by directing transport to regionalized trauma centers for more aggressive early resuscitation. If pLA improves identification of outcomes independent of clinically available prehospital variables, then it could be especially useful to risk stratify patients who do not show any initial signs of physiologic perturbation. Ultimately, protocols designed to intervene with earlier resuscitation based on pLA may have a protective effect in trauma-associated mortality. Goals of This Investigation This study sought to determine the additional value of pLA as a biomarker for mortality and morbidity in patients presenting to prehospital providers with acute trauma. We investigated the odds ratios of in-hospital outcomes in pa- tients with increased pLA compared with and adjusting for traditional covariates using multivariable logistic regression models. We then explored the improved sensitivity of iden- tifying outcomes when pLA above a threshold of 2 mmol/L was added to other traditional prehospital markers of shock, respiratory distress, and altered sensorium. PATIENTS AND METHODS We conducted an observational cohort study of consec- utive trauma patients transported to a single hospital by an air Submitted for publication October 18, 2010. Accepted for publication January 18, 2011. Copyright © 2011 by Lippincott Williams & Wilkins From the Departments of Emergency Medicine (F.G., B.S., J.Q., C.C.) and Surgery (J.-C.P.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Department of Emergency Medicine (J.-L.C.), Fundacion Valle del Lili, Cali, Colombia. Presented as a poster at the 68th Annual Meeting of the American Association for the Surgery of Trauma, October 1–3, 2009, Pittsburgh, Pennsylvania. Supported, in part, by the Fogarty International Center NIH Grant No. 1 D43 TW007560-01. Address for reprints: Francis X. Guyette, MD, Department of Emergency Medi- cine, University of Pittsburgh, Iroquois Building, Suite 400A, 3600 Forbes Avenue, Pittsburgh, PA 15261; email: guyettef@upmc.edu. DOI: 10.1097/TA.0b013e318210f5c9 782 The Journal of TRAUMA ® Injury, Infection, and Critical Care • Volume 70, Number 4, April 2011