Aspects of the invention relates to systems and methods for detecting volume status, volume overload, dehydration, hemorrhage and real time assessment of resuscitation, as well as organ failure including but not limited cardiac, renal, and hepatic dysfunction, of a living subject using non-invasive vascular analysis (NIVA). In one embodiment, a non-invasive device, which includes at least one sensor, is used to acquire vascular signals from the living subject in real time. The vascular signals are sent to a controller, which processes the vascular signals to determine at least one hemodynamic parameter, such as the volume status of the living subject. In certain embodiments, the vascular signals are processed by a spectral fast Fourier transform (FFT) analysis to obtain the peripheral vascular signal frequency spectrum, and the volume status of the living subject may be determined by comparing amplitudes of the peaks of the peripheral vascular signal frequency spectrum.
