1. A monitoring device comprising: a part for acquiring a signal indicating a level of consciousness; a part for acquiring an arterial blood pressure signal; a display; and a processor or processors arranged to cause the display to display, in one operating mode and for simultaneous viewing, an image showing the blood pressure signal over time, an image showing cardiac output or stroke volume over time, an image showing systemic vascular resistance over time and an image showing the level of consciousness over time based on the signal indicating the level of consciousness.