Embodiments of the present disclosure relate to determining changes in a vasculature by analyzing changes in one or more attributes of a plethysmographic signal. According to certain embodiments, an apparatus may obtain plethysmographic signals prior to and subsequent to the administration of a vasoactive stimulus. The apparatus may include a processing unit configured to analyze and to compare attributes of the plethysmographic signals. The processing unit may correlate any changes in signal attributes to a change in a physiological condition of the vasculature (e.g., vascular tone/compliance). The apparatus may also include a display unit configured to present any changes in the vasculature as well as any alarms in response to a trigger from the processing unit.
