The initial management of the multiple trauma victim requires evaluation for potential hemorrhage and ongoing monitoring to assess the efficacy of resuscitation and avoid complications related to hemorrhagic shock. A variety of strategies exist to assess circulatory status, including hemodynamic monitoring, tissue perfusion measurement, and use of serum markers of metabolism. We review available technologies used to assess fluid status and tissue perfusion in patients with blood loss or hemorrhagic shock, discuss how these methods can be used effectively and efficiently during initial trauma resuscitation to guide therapy and disposition, and suggest directions for future research to improve outcomes by providing more appropriate and timely care and avoiding unnecessary complications.