Delirium is an acute and relatively sudden (developing over hours to days) decline in attention-focus, perception, and cognition. In medical usage it is not synonymous with drowsiness, and may occur without it. Delirium is not the same as dementia (the two entities have different diagnostic criteria), though it commonly occurs in demented patients.
Delirium may be of a hyperactive variety manifested by 'positive' symptoms of agitation or combativeness, or it may be of a hypoactive variety (often referred to as 'quiet' delirium) manifested by 'negative' symptoms such as inability to converse or focus attention or follow commands. While the common non-medical view of a delirious patient is one who is hallucinating, most people who are medically delirious do not have either hallucinations or delusions. Delirium is commonly associated with a disturbance of consciousness (e.g., reduced clarity of awareness of the environment). The change in cognition (memory deficit, disorientation, language disturbance) or the development of a perceptual disturbance, must be one that is not better accounted for by a pre-existing, established, or evolving dementia. Usually the rapidly fluctuating time course of delirium is used to help in the latter distinction.
Delirium itself is not a disease, but rather a clinical syndrome (a set of symptoms), which result from an underlying disease or new problem with mentation. Like its components (inability to focus attention, confusion and various impairments in awareness and temporal and spatial orientation), delirium is simply the common symptomatic manifestation of early brain or mental dysfunction (for any reason).
Without careful assessment, delirium can easily be confused with a number of psychiatric disorders because many of the signs and symptoms are conditions present in dementia, depression, and psychosis. Delirium is probably the single most common acute disorder affecting adults in general hospitals. It affects 10-20% of all hospitalized adults, and 30-40% of elderly hospitalized patients and up to 80% of ICU patients.
Treatment of delirium requires treatment of the underlying causes. In some cases, temporary or palliative or symptomatic treatments are used to comfort patients or to allow better patient management (for example, a patient who without understanding is trying to pull out a ventilation tube that is required for survival).
Educational information is available for medical and non-medical persons with videos, management protocols, links to references, lectures, recent evidence from studies, implementation packets for hospitals, and even comments to families and loved ones for those witnessing someone going through a delirious episode See the Resources section.
In common usage, delirium is often used to refer to drowsiness, disorientation, and hallucination. In broader medical terminology, however, a number of other symptoms, including sudden inability of focus attention, and even (occasionally) sleeplessness and severe agitation and irritability, also define "delirium," and hallucination, drowsiness, and disorientation are not required.
The core features are:
Common features also tend to include:
It is a corollary of the above differential criteria that a diagnosis of delirium cannot be made without a previous assessment or knowledge of the affected person's baseline level of cognitive function.
Several valid and reliable rating scales now exist which can be used to accurately diagnose delirium. www.icudelirium.org
Since delirium may occur in very many grades of severity, all symptoms may occur with varying degrees of intensity. A mild disability to focus attention may result in only a disability in solving the most complex problems. As an extreme example, a mathematician with the flu may be unable to perform creative work, but otherwise may have no difficulty with basic activities of daily living. However, as delirium becomes more severe, it disrupts other mental functions, and may be so severe that it borders on unconsciousness or a vegetative state. In the latter state, a person may be awake and immediately aware and responsive to many stimuli, and capable of coordinated movements, but unable to perform any meaningful mental processing task at all.
Disorientation (another symptom of confusion, and usually a more severe one) describes the loss of awareness of the surroundings, environment and context in which the person exists. It may also appear with delirium, but it is not required, as noted. Disorientation may occur in time (not knowing what time of day, day of week, month, season or year it is), place (not knowing where one is) or person (not knowing who one is).
Cognitive function may be impaired enough to make medical criteria for delirium, even if orientation is preserved. Thus, a patient who is fully aware of where they are and who they are, but cannot think because they cannot concentrate, may be medically delirious. The state of delirium most familiar to the average person is that which occurs from extremes in pain, lack of sleep, or emotional shock.
Because most high level mental skills are required for problem solving, including ability to focus attention, this ability also suffers in delirium. However, this is a secondary phenomenon, since problem-solving involves many sub-skills and basic mental abilities, any of which may be impaired in a delirious patient.
Strange beliefs may also be held during a delirious state, but these are not considered fixed delusions in the clinical sense as they are considered too short-lived (i.e., they are temporary delusions - such as thinking that a nurse is a person from his/her past trying to cause injury). Interestingly, in some cases sufferers may be left with false or delusional memories after delirium, basing their memories on the confused thinking or sensory distortion which occurred during the episode of delirium. Other instances would be inability to distinguish reality from dreams.
Abnormalities of affect which may attend the state of delirium may include many distortions to perceived or communicated emotional states. Emotional states may also fluctuate, so that a delirious person may rapidly change between, for example, terror, sadness and jocularity.
Delirium, like mental confusion, is a very general and nonspecific symptom of organ dysfunction, where the organ in question is the brain. In addition to many organic causes relating to a structural defect or a metabolic problem in the brain (analogous to hardware problems in a computer), there are also some psychiatric causes, which may also include a component of mental or emotional stress, mental disease, or other "programming" problems (analogous to software problems in a computer).
Delirium may be caused by severe physical illness, or any process which interferes with the normal metabolism or function of the brain. For example, fever, pain, poisons (including toxic drug reactions), brain injury, surgery, traumatic shock, severe lack of food or water or sleep, and even withdrawal symptoms of certain drug and alcohol dependent states, are all known to cause delirium.
In addition, there is an interaction between acute and chronic symptoms of brain dysfunction; delirious states are more easily produced in people already suffering with underlying chronic brain dysfunction.
A very common cause of delirium in elderly people is a urinary tract infection, which is easily treatable with antibiotics, reversing the delirium.
A mnemonic acronym for the myriad causes of Delirium is 'I WATCH DEATH'
Too many to list by specific pathology, major categories of the cause of delirium include:
The most common behavioral manifestation of acute brain dysfunction is delirium, which occurs in up to 60% to 80% of mechanically ventilated medical and surgical ICU patients and 50% to 70% of non-ventilated medical ICU patients. During the ICU stay, acute delirium is associated with complications of mechanical ventilation including nosocomial pneumonia, self-extubation, and reintubation. ICU delirium predicts a 3- to 11-fold increased risk of death at 6 months even after controlling for relevant covariates such as severity of illness. Of late, delirium has been recognized by some as a sixth vital sign, and it is recommended that delirium assessment be a part of routine ICU management. The elderly may be at particular risk for this spectrum of delirium and dementia. A firm understanding of the pathophysiologic mechanisms of delirium remains elusive despite improved diagnosis and potential treatments. www.icudelirium.org
Palliative or symptomatic treatment of delirium is sometimes necessary to make a patient comfortable. Distressing symptoms of delirium are sometimes treated with antipsychotics, preferably those with minimal anticholinergic activity, such as haloperidol or risperidone, or else with benzodiazepines, which decrease the anxiety felt by a person who may also be disoriented, and has difficulty completing tasks. Conversely, recent research however suggests that delirium may in fact be exacerbated by benzodiazepines. Bearing this in mind, any drug does not address the underlying cause of delirium, and may mask changes in delirium which themselves may be helpful in assessing the patient's underlying changes in health, their use is difficult. Other evidence also suggests that non-pharmacological measures may also be effective in decreasing the incidence of delirium. Because delirium is a mere symptom of another problem which may be very subtle, the wisdom of treatment of the delirious patient with drugs must overcome natural skepticism, and requires a high degree of skill.
Benzodiazepines are usually used in the treatment of delirium associated with alcohol withdrawal.
There have been reports that cholinesterase inhibitors might be effective in treating delirium, but there is little evidence for this.
Further information and resources, including guidelines from other countries are also available on the European Delirium Association website www.europeandeliriumassociation.com
There is a powerful presentation including delirium on the older peoples mental health website www.olderpeoplesmentalhealth.csip.org.uk/lets-respect/presentation-slides.html which includes further statistics relating to delirium in older adults in hospitals in England. Also further resources on delirium are available on this site.