Delirium is a common condition, occurring in 10-20% of all hospital admissions.⁽¹⁾ It is more likely to occur in elderly patients, particularly in those patients who already have some impairment of cognitive ability. It is a potentially preventable clinical syndrome among persons who are 65 years of age or older. Development of delirium often initiates a chain of events resulting in the loss of independence, an increased risk of morbidity and mortality, and increased health care costs due to prolonged hospital stay and care needs ^{(1, 2, 3, 4)}. Acute onset of delirium affects 10 to 30 percent of hospitalized patients with medical illness ⁽¹⁷⁾; more than 50 percent of persons in certain high-risk populations are affected. Conditions associated with delirium can at times be fatal; hence it i's important to investigate immediately.

The mortality rates among hospitalized patients with delirium range from 22 to 76 percent,^{(6, 18)} as high as the rates among patients with acute myocardial infarction or sepsis. The one-year mortality rate associated with cases of delirium is 35 to 40 percent.⁽⁷⁾
Delirium can be of acute onset or can be progressive over days or weeks. There can be a fluctuating level in consciousness during this period ranging from agitation to excessive sleepiness.⁽⁸⁾ Impairment of cognitive skills, like memory, language, self care and organization are seen during the early phase of delirium. Delirium is often unrecognized by the patient's physicians and nurses,^(1,7) in part because of its fluctuating nature, its overlap with dementia, lack of formal cognitive assessment. To make a diagnosis of delirium one must demonstrate each of the 4 mentioned features: fluctuating consciousness, change in cognition status, acute onset of symptoms, possible cause behind delirium onset e.g. - drugs, infections, electrolyte imbalance & other⁽²⁹⁾.

Delirium has a negative impact on prognosis and this has been confirmed in several recently published prospective studies that were mainly focussed on length of hospital stay, functional ability, cognitive function and mortality. Higher mortality rates after discharge have been reported repeatedly for patients who experienced an episode of delirium, up to 10% in the first year after delirium had occurred⁽⁹⁾. The average prevalence of delirium in older people in general hospitals is 20% (range 7 - 61%). For post fracture neck of femur the prevalence varies from 10% to 50%⁽³⁰⁾.

Symptoms of Delirium: Symptoms of delirium may range from attention impairment, memory loss/ impairment, apathy and withdrawal, sleep disturbances (reversal of the sleep-wake cycle is common), emotional lability, perceptual disturbances. Several focal neurological signs and symptoms may be present in delirium regardless of cause. They include gait problems; tremor; asterexis; myoclonus jerks, paratonia (e.g., gegenhalten) of the limbs and especially of the neck; difficulty reading and writing; and visuo-construction problems, such as copying designs and finding words⁽⁸⁾.

Certain signs and symptoms can help physicians distinguish between delirium and a preexisting psychiatric disorder. For example, visual hallucinations are an indicator of an underlying metabolic disturbance or adverse effect of medication or substance abuse. While visual hallucinations can occur in patients with primary psychiatric illnesses such as schizophrenia, they are much less common than auditory hallucinations.

Indicators of Delirium:⁽¹⁷⁾

• Cloudiness of conscious level
  
• Presence of acute medical illness
  
• Visual/ Auditory hallucinations
  
• Fluctuating levels of consciousness (Agitation/ Excessive sleepiness)
  
• Acute onset of psychiatric symptoms without prior history of psychiatric illness
  
• Acute onset of new or different psychiatric symptoms with history of prior psychiatric illness
  
• Patient described as "confused" or "disoriented"
  
• Diffuse slow waves or epileptiform discharges on EEG

Common causes of Delirium: There is an endless list of conditions leading to acute onset of delirium especially in elderly patients⁽¹⁵⁾. Some of the common medical problems leading to acute onset of confusion in elderly patients are

• Dementia
  
• Post Surgical status
  
• Cardiac
  
• Hip
  
• Transplant
  
• Infections: Chest, urinary, others
  
• Sepsis
  
• Abrupt discontinuation of alcohol or drugs
  
• Malnourishment: Anaemia
  
• Dialysis
  
• Parkinson's disease
  
• Post Stroke status
  
• Carcinoma including metastases⁽¹⁶⁾
  
• Fluid and electrolyte imbalance
  
• Heart failure
  
• Hypo/ Hyperthermia
  
• Diabetes (hypo- or hyperglycaemia)
  
• Thyroid problems
  
• Encephalitis
  
• Epilepsy: Post Ictal
  
• Alcohol withdrawal
  
• Gastrointestinal bleed
  
• Respiratory failure
  
• Subdural haematoma
  
• Brain Tumour
  
• Drugs: use of 3 or more medications; Steroids, Anti parkinsonian medications, anti cholinergics, benzodiazepines, other sedatives, etc.
  

Infections are the single most common cause of acute onset of delirium in elderly patients followed by medications changes or withdrawal and electrolyte imbalances.⁽¹⁰⁾

Screening Tools for Delirious Elderly Patients:

Common screening tools used for early assessment of "Delirious" patients are

• Folstein mini mental state examination (MMSE)⁽¹¹⁾: It screens for deficits in orientation, attention, memory, language, and visuoconstruction abilities. Using the MMSE several times during the course of delirium can be a way to assess improvement. Comparison with an MMSE performed before the onset of the delirium is ideal.
  
• Confusion Assessment Method (CAM)⁽¹²⁾: Includes following features
  · Acute change in mental state and fluctuating course
  · Inattention
  · Disorganised thinking
  · Altered level of concoiusness
  (The diagnosis of delirium requires the presence of features 1 and 2 and either 3 or 4)
  
• Delirium Rating Scale (DRS)
  
• Memorial Delirium Assessment Scale (MDAS)
  
• DSM-IV diagnostic criteria^{(13, 16)}
  

Differentiating Features of Delirium and Dementia

Investigations in a Delirious patient:

• Full Blood count with differential
  
• Urea and electrolyte, Serum Calcium levels
  
• Serum Glucose
  
• Renal and liver function tests
  
• Thyroid function studies
  
• Urine analysis
  
• Urine and Blood drug screen - to diagnose toxic causes
  
• Thiamine and vitamin B-12 levels
  
• Blood/ Urine Cultures
  
• ESR/ CRP
  
• Imaging Studies: Chest X- ray, CT scan Brain/ MRI Brain
  
• EEG: shows slowing of the posterior dominant rhythm and increased generalized slow-wave activity are observed on electroencephalogram (EEG) recordings
  
• Other Tests includes: ECG, Pulse oxymetry, Lumbar Puncture.

Management of Acute Delirium state: The patient should be nursed in a good sensory environment and with a reality orientation approach, and with involvement of the multi-disciplinary team⁽²⁹⁾. When delirium is diagnosed or suspected, the underlying causes should be sought. Despite every effort, no cause for delirium can be found in approximately 16% of patients⁽¹⁹⁾. The initial steps in managing patients with delirium are to conduct a careful review of the medical history, physical examination findings, laboratory evaluations, and any drugs the patient is using, including over-the-counter agents, illicit drugs, and alcohol. Information from patients' current and past medical history, as well as the physical examination, should guide the initial work-up. Often the aetiology will be fairly obvious from the history and basic laboratory tests⁽²⁰⁾.

Symptomatic treatment for acute delirium may include the use of antipsychotic drugs to control agitation and hallucinations, and to clear the sensorium. Haloperidol has been studied most often in the symptomatic management of delirium ⁽²¹⁾ but risperidone^{(22, 23)} and olanzapine,⁽²⁴⁾ which are newer, atypical antipsychotics have been the subjects of a few case reports. Two small studies^{(23, 25)} with olanzapine suggested that this drug might be a useful alternative in the treatment of delirium.

Fluid and nutrition management should be done carefully especially in cases of dyselectrolytemia and in alcohol related delirium. Appropriate antibiotics should be initiated after proper culture and sensitivity results in case of UTI, chest infections, sepsis.
An environmental modification^{(26, 27, 28)} is an important part of management for delirious patients.

• Reorientation techniques or memory cues such as a calendar, clock, and family photos may be helpful.
  
• The environment should be made stable, quiet, and well-litghted. Support from a familiar nurse and family should be encouraged.
  
• Family members and staff should explain proceedings at every opportunity, reinforce orientation, and reassure the patient.
  
• Sensory deficits should be corrected, if necessary, with eyeglasses and hearing aids.
  
• Physical restraints should be avoided⁽³¹⁾. Delirious patients may pull out intravenous lines, climb out of bed, and may not be compliant. Perceptual problems lead to agitation, fear, combative behaviour, and wandering.
  

Do’s and Don’ts in a Delirious patient:⁽²⁹⁾

Preventing Complications of Delirium:⁽²⁹⁾, Common complications encountered in delirious patients are

• Falls and related injuries
  
• Pressure sores
  
• Nosocomial infections
  
• Functional impairment
  
• Continence problems
  
• Over sedation
  
• Malnutrition
  

Restraining of patients has shown to be of no benefit (31), Readjusting the height of bed, if necessary providing mattress on the floor should be used rather than restraining the patient. Pressure sore risk assessment should be made mandatory for all delirious patients as soon as they are admitted. Provision of pressure relieving mattress, preventing malnutrition, regular toileting and prompt treatment of UTI's should prevent pressure sores and avoid their complications⁽²⁹⁾.

Delirium can be a frightful experience for patient and family members⁽³²⁾. Patients may fear that they are losing their minds and reassuring them is an important part of the treatment plan. Educating patients and family members about delirium and its association with underlying medical conditions is important. Considerable morbidity and mortality is associated with delirium. Patients with delirium generally have longer hospital stays and more medical complications, such as infections, pressure ulcers, and malnutrition. Mortality is also higher in patients with delirium, probably as a result of more severe underlying medical pathology. Counselling and support have shown to upbeat the morale of previously delirious patients and relatives⁽³²⁾.

REFERENCES