 The Brooke Army Medical Center can use near-infrared diffuse optical spectroscopy to provide functional physiologic tissue and organ information without ionizing radiation and without withdrawing any blood, in a cost-effective and rapid manner. Monitoring for the onset of circulatory shock in a wounded soldier on the battlefield is typically performed by measurement of arterial blood pressure, arterial oxygen saturation, or simple auscultation of the pulse. Shock is typically recognized by non-specific signs and subjective symptoms such as cold clammy skin, pallor, weak thready pulse, unstable vital signs, and diminished mentation. 