First, what does a critical care unit look like? What happens behind those critical care doors (Fig. 8.1)? If asked, most people will describe a critical care unit as a place of ‘wires, tubes and machines’. Anecdotally, most nurses at interview for critical care posts will say that you can care for one patient as opposed to six, giving all the care required. So what do we know from the evidence about critical care, and how can it help us?