**3.1.3 Hip fracture**

Hip fracture patients are at increased risk of delirium because of the trauma associated with the injury and the rapid progression to hospitalization and surgery, in addition to the pain and loss of function (Schor et al., 1992; Williams et al., 1985). Delirium has been reported to be seen in 20%–40% of patients with hip fracture at the time of hospital admission (Magaziner et al., 1989; Gustafson et al., 1991; Marcantonio et al., 2002 ).

A Review of the Etiology Delirium 193

uncertainty for depression as a precipitating factor for delirium (National Clinical Guideline

Precipitating factors are the acute insults that trigger the mechanisms resulting in delirium (Fong et al., 2009; Inouye, 1999). Factors that have been reported to precipitate delirium are: anemia (Joosten et al., 2006), hypoxaemia (Kazmierski et al., 2010), Intensive Care Unit admission (Branco et al., 2011), electrolyte abnormalities (Korevaar et al., 2005), sleep deprivation (Weinhouse et al., 2009), pain, bladder catheter use, drugs and surgery (Burns et al., 2004). Biochemical abnormalities such as hyponatremia and hypokalemia and hyperuricemia and low body mass index and sensory impairment reflects the severity of the

Inouye and Charpentier performed a study to establish a predictive model for development of delirium and identified 5 independent precipitating factors for delirium in the elderly: use of physical restraints, malnutrition, more than 3 medications added, use of bladder catheter and any iatrogenic event (Inouye & Charpentier, 1996). Among the predisposing

The incidence of post-operative delirium ranges from 5% to 15%(Deiner& Silverstein, 2009). Certain high-risk groups have increased rates of delirium. Delirium has been reported in 16.3% after cardiac surgery (Kazmierski et al., 2010). Rates as high as 30.2% after hip surgery (Lee et al., 2011) and 50% have been reported in elderly patients (Inouye et al., 1993; Dasgupta & Dumbrell, 2006). Factors that increase the risk of delirium in surgical patients include electrolyte disturbances, increased age, dementia, low cardiac output, perioperative hypotension, postoperative hypoxia, and use of anticholinergic drugs. (Michaud et al., 2007; Norkiene et al., 2007). Pandharipande et al. found that 70% of the combined surgical and trauma ICU patients had at least one episode of delirium (Pandharipande et al., 2007).

Delirium is characterised by a global cerebral dysfunction resulting in a generalized reduction in cerebral oxidative metabolism and an imbalance of several neurotransmitters in the brain. Any drug that interferes with these neurotransmitter systems or with the supply or use of substrates for metabolism of the central nervous system can cause delirium (Gray et al., 1999; Moore & O'Keeffe, 1999; Nayeem & O'Keeffe, 2003). For a drug to be clearly implicated as an etiological factor in delirium, the administration of the drug should precede the onset of symptoms of delirium within a short time duration and withdrawal of the drug should result in a return to baseline cognitive functioning (Moore

The causal association of drugs to delirium is most clear for anticholinergic drugs with muscarine receptor affinity (White et al., 2007). Antihistaminics, antipsychotics, tricyclic antidepressants, digoxin, frusemide, isosorbide dinitrate, warfarin, dipyridamole, codeine,

underlying precipitating cause of delirium (Elie et al., 1998; Mussi et al., 1999).

factors, surgery and drugs will be discussed in this section.

Center; Steiner, 2011).

**3.2.1 Surgery** 

**3.2.2 Drugs** 

& O'Keeffe, 1999).

**3.2.2.1 Anticholinergic drugs** 

**3.2. Precipitating factors** 

The most common of delirium in hip fracture patients were reported as drugs that have central nervous system effects, infections, fluid-electrolyte disturbances, metabolic/ endocrine disturbances, intracranial processes, cardiopulmonary compromise and/or drug withdrawal and sensory/environmental causes (Brauer et al., 2000).
