Confusion States in the Elderly — Investigation and Management

Confusion States in the Elderly — Investigation and Management Fifteen–Twenty High-Yield Points Definition and classification

Confusion in an older patient is a presentation, not a diagnosis. Disorders causing confusion fall into three groups: (i) acute disorders related to acute illness, drugs and environment (delirium); (ii) slowly progressive cognitive impairment (dementia); (iii) impaired cognition associated with affective disorders and psychoses.

Cognitive impairment in the elderly usually results from multiple interacting processes rather than a single cause. Old age alone never causes dysfunctional cognitive impairment.

Delirium is an acute or subacute alteration in mental status. Prevalence is about 15% on admission in hospitalised older patients and incidence during admission may be up to one-third. It may persist for days to weeks and is therefore common in post-acute care.

The key features of delirium are: disturbance of consciousness (reduced clarity of awareness with reduced ability to focus, sustain or shift attention) and a change in cognition not better accounted for by dementia, developing over hours to days and fluctuating, with evidence of a physical cause.

The Confusion Assessment Method (CAM) requires features 1 and 2 plus either 3 or 4: (1) acute onset and fluctuating course, (2) inattention, (3) disorganised thinking, (4) altered level of consciousness. Level of consciousness is graded alert, vigilant, lethargic, stupor or coma.

Delirium is subtyped as hyperalert (hyperactive), hypoalert (hypoactive) or mixed. The hypoactive form is commoner in the elderly and is the form most often missed.

The 4AT is a rapid screening tool with sensitivity 0.88 and specificity 0.88 in people aged 65 and over across emergency, medical, stroke and surgical settings.

Three questions guide the diagnosis: Is the onset acute? Are physical factors contributing? Are psychological factors contributing?

Common causes of delirium: metabolic disorders (hypoxia, hypercarbia, hypo- or hyperglycaemia, hyponatraemia, azotaemia); infections; reduced cardiac output (dehydration, acute blood loss, myocardial infarction, heart failure); small cortical stroke; drugs and drug intoxication including alcohol; hypo- or hyperthermia; acute psychoses; transfer to unfamiliar surroundings, especially where sensory input is reduced; and, easily forgotten, faecal impaction and urinary retention.

Anaesthesia poses a special risk. Predisposing factors include impaired sensory function and sensory deprivation, sleep deprivation, immobilisation and transfer to an unfamiliar environment.

Assessment comprises: focused history and physical examination (including assessment for delirium and depression and identification of comorbidities such as sensory impairment), functional status assessment, mental status examination, and selected laboratory studies to exclude reversible causes.

A collateral history is mandatory to establish the pre-morbid baseline and the tempo of change.

Baseline investigations: full blood count, urea and electrolytes, calcium, glucose, liver and renal function, thyroid function, vitamin B12, CRP, urinalysis and culture, chest radiograph, ECG, and pulse oximetry. Blood cultures if febrile.

A full drug review is the single highest-yield investigation. Every medication that may be worsening cognition should be stopped or avoided.

Brain imaging should not be done automatically in every patient with cognitive impairment. CT is indicated for focal neurological signs, head injury, anticoagulation, suspected subdural haematoma, or an unexplained failure to improve.

Lumbar puncture is reserved for suspected CNS infection; EEG for suspected non-convulsive status epilepticus, which in the elderly may present purely as confusion.

Treat the underlying cause and correct every contributing factor simultaneously — hypoxia, sepsis, dehydration, pain, constipation, urinary retention, and drug toxicity.

Non-pharmacological measures come first: preparing older patients for changes in location, placing familiar objects in the surroundings, and maximising sensory input with adequate lighting, clocks and calendars. Restore spectacles and hearing aids; encourage early mobilisation; promote normal sleep-wake cycles; involve family.

Avoid physical restraints in hospitalised older patients with delirium or dementia unless essential for safety and medical care. Avoid psychoactive drugs where they can be avoided.

If drug treatment is unavoidable because of danger to self or others, use the lowest effective dose of a single antipsychotic for the shortest possible time, with regular review. Benzodiazepines are reserved for alcohol or benzodiazepine withdrawal, where they are the treatment of choice. Melatonin or melatonin receptor agonists reduce the prevalence of delirium and length of ICU stay and improve sleep quality.