The present invention relates to a method and a device for determining the hydro-dynamic properties of the fluid system surrounding the brain and the spinal cord, the so called cerebrospinal fluid system, whereby the method comprises continuous pressure measurement through a fluid contact passage and active infusion of artificial cerebrospinal fluid through another fluid contact passage to a number of pressure-flow levels, and analysis of the connections between the measured pressures and flows. The method uses an adaptive way of procedure which on each pressure-flow level takes account for the measure time and the patients fluctuations in physiologic signals for calculating in real time when the relation between the measure time and measure accuracy in pressure and flow on the actual pressure-flow level is sufficient and at an optimum, whereupon the investigation or examination is automatically proceeding to the next level according to a predetermined protocol. In this way, the method gives rise to an investigation with measurements having sufficient pressure and flow information on each level, which forms a base for determination in a correct manner, with an uncertainty estimate, of the patients hydrodynamic parameters. The device comprises a hose pump (1) for infusion of artificial cerebrospinal fluid in a bottle or bag (2), a standardized hose set including a pump hose (3) and pressure transducers (4) for continuous registration of the intracranial pressure, an invasive contact object (5) for creating fluid contact with the cerebrospinal fluid system and consisting of needles or a catheter, as well as a computer (12) with software for computerized collection and analysis as well as control of pump speed. The device uses a computerized implementation of the above-mentioned adaptive method in order to systematically and safely carry through a standardized protocol which generates pressure and flow information which the software of the measure system then uses for
