The American College of Surgeons requires trauma centers to use six minimum criteria (ACS-6) for full trauma team activation: hypotension, gunshot wound to the neck or torso, Glasgow Coma Scale (GCS) score < 9, respiratory compromise, transfers receiving blood transfusion, or physician discretion. Our goal was to evaluate the effect of adding varying shock index (SI) thresholds to the ACS-6 in an adult trauma population with the hypothesis that SI would significantly improve sensitivity at the expense of an acceptable decrease in specificity