Management of the polytrauma patient with or without TBI in the prolonged field care (PFC) setting especially when prolonged damage control resuscitation (pDCR) is required represents an extraordinary challenge. While there is a desire to develop new therapeutic agents to improve survival and mitigate tissue injury and organ failure, we have not yet developed tools which assist in helping providers maximize use of supportive treatments such blood transfusion, volume expansion, vasopressor use, etc. in a precision manner for goal directed therapy (GDT). The use of goal GDT has been demonstrated to be life saving for both surgical and medical populations with severe hemodynamic compromise but is difficult to implement with current invasive and noninvasive tools because of their lack of precision or form factor and expense. This proposal will scale testing of two novel noninvasive measures that could allow forreal-time use of GDT in the PFC/pDCR setting. These include: 1) Resonance Raman Spectroscopy (RRS) to measure tissue hemoglobin oxygen saturation (StO2) of the buccal mucosa as a substitute for central or mixed venous hemoglobin oxygen saturation (ScvO2) and potentially lactate, and 2) Dynamic Respiratory Impedance Volume Evaluation (DRIVE) of the limb as a substitute for ultrasound of the inferior/superior vena cava and central venous pressure (CVP). RRS-StO2 uses a special wavelength of light to determine how much oxygen a tissue is receiving. DRIVE uses a small amount of electricity passed through tissue to measure blood volume moving in and out of the tissue during breathing.