display means is a flat screen panel and incorporates an upper panel of images 21 identical to that shown in fig1 and discussed above both trend displays left hand panels 22 and acute change displays with an expanded y axis over a 2 minute time period right hand panels 23 are utilised the display means incorporates a second panel 24 including an image of the raw analogue blood pressure signal 25 this signal is useful as an indication of the quality of the right heart signal an indication of current systolic 26 and diastolic 27 blood pressure is also presented relevant outputs may also be displayed derived from this data such as the change in cardiac output reflected in the signal 28 this display may be switched for an event response panel 14 in certain instances such as the event response panel shown in fig1 the display means also incorporates a third panel including the preload fluid responsiveness parameter pulse pressure variation pvv 29 this can be switched for stroke volume variation as desired svv 210 both a trend display 211 and acute changes display 212 are utilised the trend display shows pvv plotted over time 10 minutes in this instance and the acute changes display shows pvv per beat using an expanded y axis both the trend display and acute changes display incorporate a target zone a shaded band in this case 213 to provide an indication of the desired pvv value namely around 10 15 the respiratory variation is a useful indicator of the signal quality of the right heart venous return preload status hemodynamic parameters are derived from the patient 39 s existing arterial pressure waveform using the pulseco algorithm.