1. A system, for determining an estimated intracranial pressure (ICP) of a first patient, comprising: a processing module that: receives a first input based on a first plurality of measurements of a first physiological parameter of the first patient, the first physiological parameter correlating with ICP; receives a second input based on a second plurality of measurements of a second physiological parameter of the first patient, the second physiological parameter correlating with ICP; processes the first and second inputs based on an ICP model; and outputs data indicative of the estimated ICP of the first patient; wherein the ICP model is chosen from a plurality of potential ICP models, each of the potential ICP models having an associated mapping function that maps values of said first and second physiological parameters to at least one dissimilarity value, each of said at least one dissimilarity value representing a dissimilarity between an estimated ICP value or function and an observed ICP value or function.