There are several risk factors for the development of delirium. Some of these are fixed (e.g. coexisting dementia and frailty), whilst some are modifiable. Modifiable risk factors are highlighted in Fig. 13.1. Identification (and minimisation) of these may help to prevent an episode of delirium. Once delirium is established, there is no specific treatment other than identification and removal of the contributing factors.

Typically, predisposing non-modifiable factors (dementia, serious illness, frailty) interact with precipitating, modifiable factors (sedatives, infections, surgery, electrolyte abnormalities) for delirium to develop. The commonest risk factors for delirium include age 65 years or older (who constitute 50–60% of all non-ambulatory patients in typical EDs), cognitive impairment (past or present) and/or dementia, current hip fracture (10% present with delirium, with 16–62% incidence postoperatively) [12] and any severe illness (a clinical condition that is deteriorating or is at risk of deterioration). Other important precipitating agents for delirium include anticholinergic and antiparkinsonian drugs; inflammation from trauma, infection or surgery; any acute stress mediated by increased cortisol levels; hypoxia, hypoglycaemia, fluid, electrolyte and other metabolic derangements; and hypotension and hypothermia.

There are no ‘routine’ investigations for delirium in the ED, and based on a thorough history, collateral information, clinical presentation and physical examination, the following investigations may be employed as needed: haemoglobin, cell count and differential, urea, creatinine and electrolytes, bone profile, chest X-ray, urine dipstick and culture (can be helpful to exclude UTI—see Chap. 16) and CT brain (2–7% pickup rate for a significant neurological lesion) [13].

Once delirium has been detected, management is directed towards addressing the underlying precipitating factors as described in Fig. 13.1.

The most important step in the ED to improve delirium recognition and management is to institute routine screening for the condition and support it by appropriate processes that prevent its development. For example, avoidance of benzodiazepines or anticholinergics may help prevent an episode of delirium in susceptible older people. Medicines with anticholinergic effects are a frequent cause of delirium in older people, and ‘anticholinergic burden’ is a good means of understanding this risk [14]. Other considerations such as maintaining orientation to surroundings, meeting needs for nutrition and fluids, promoting mobility within the limitations of physical condition and providing visual and hearing adaptations for patients with sensory impairments have been shown to reduce the incidence of delirium in hospital settings (Hospital Elder Life Programme; OR 0.6, CI 0.39–0.92) [15]. These principles could be applied as feasible in the ED although there are no related studies. Appropriate management of pain, constipation, retention of urine and avoiding ‘lines and tubes’ that restrict mobility also benefits the older person. Environmental considerations include noise insulation, natural lighting, sympathetic décor, signage and low trolley.