1. A hemodynamic monitor for a subject comprising: (a) a processor comprising software arranged to continuously analyse and process at least one of a blood pressure, arterial volume, and a plethysmographic signal obtained from the subject in order to derive a plurality of complementary parameters throughout monitoring of the subject (b) display means displaying images representing the derived plurality of complementary parameters, wherein the images comprise: (1) at least one image representing graphically at least one stress related hemodynamic parameter plotted against time to provide an early or immediate indication of a change in hemodynamic status, thereby indicating a requirement for an intervention (2) at least one image representing graphically at least one fluid responsiveness parameter plotted against time to provide an indication of hydration level and associated ventricular pre-load status of the subject to determine whether an intervention is required, wherein the intervention comprises modulating hydration level or modulating any other therapeutic administered to influence hydration or hemodynamic status of the subject characterised in that the at least one stress related hemodynamic parameter or the at least one fluid responsiveness parameter is displayed in a form of at least one image representing current changes in the parameter in combination with at least one image representing longer term changes in the parameter auto-scaled to duration of monitoring of the subject, or scaled to any representative longer period of time, wherein the at least one image displaying current changes in the parameter comprises an expanded view of a suitable portion of the auto-scaled or longer-scaled image thus facilitating monitoring of current changes in the parameter whilst simultaneously allowing monitoring of longer term changes in the parameter.