Patients will be assessed on a four hourly basis, and any uncontrolled symptoms will be recorded. The main symptom of interest is agitation ("delirium"), which has multiple causes, including dehydration and kidney failure. Uncontrolled symptoms will be appropriately treated, e.g. patients with pain will be given painkillers. Equally, problems relating to the fluids given by a drip will also be recorded. Involvement in the study will not interfere with the patient's general care, and there will be no additional blood or other tests.