Why is Delirium
a high prevalence, and substantial morbidity and mortality, delirium,
or an acute confusional state, is frequently misdiagnosed by physicians.
Delirium occurs in 10 to 15% of hospitalized medical and surgical
adult patients. Prevalence rates vary greatly, depending on the
patient population: surgical (15 to 40%), critical care (20 to 40%),
psychiatric and neurological (20 to 30%), or general medicine (15
to 20%). Recent studies report mortality rates from 15 to 30%. Other
complications include falls, aspirations, pressure ulcers, immobility
are the Clinical features of Delirium?
is a clinical diagnosis for which there are three hallmark criteria:
1) disturbance of consciousness (i.e. reduced clarity of awareness
of the environment) with reduced ability to focus, sustain, or shift
attention, 2) a change in cognition (such as memory deficit, disorientation,
language disturbance) or the development of a perceptual disturbance
that is not better accounted for by a preexisting conditions such
as dementia; and 3) acute onset. Additionally, many delirious patients
are lethargic or stuporous. Thinking is disorganized resulting in
incoherent or rambling speech, and memory is impaired. Disorientation
to time and place follows, but disorientation to person is rarely
patients describe persecutory delusions, suspiciousness, bizarre
thoughts and images, and loose associations. Perceptual abnormalities
may include distortions, illusions, or frank hallucinations. Visual
illusions and hallucinations are most common, followed in frequency
by auditory and tactile illusions. Hallucinations occur less frequently
in the elderly than in middle-aged persons.
Does Delirium Differ From Dementia and Sundowning?
frequently mistake delirium for dementia. Whereas, with rare exception,
dementia presents insidiously, delirium presents as an acute loss
of global cognitive function in the setting of an acute medical
or surgical illness . However, dementia and delirium are not mutually
exclusive; it is common to find a demented patient with a superimposed
delirium. Distinguishing dementia from delirium superimposed on
dementia requires knowledge of the patients prior cognitive function.
The delirious patient with no history of dementia manifests new
cognitive deficits, whereas delirious patients with a prior dementia
demonstrates a manifests a worsening of baseline cognitive dysfunction.
If present, lethargy or stupor always indicate delirium, as these
physical signs are not manifestations of dementia. Because the symptoms
of delirium are exacerbated by sensory deprivation, delirium is
often equated with sundowning, a behavioral phenomenon of agitation
caused by sensory deprivation. However, delirium is a psychiatric
diagnosis with specific diagnostic features, and significant morbidity
and mortality, not a description of behavior.
are the Common Causes of Delirium?
acute illnesses can precipitate delirium: systemic disease outside
the central nervous system (metabolic, infectious, endocrine, cardiorespiratory,
and paraneoplastic syndromes); primary intracranial disease (infectious,
degenerative dementia, collagen vascular, mass lesion, trauma, and
stroke); exogenous toxic agents including some medications; withdrawal
from drugs; depression; and epilepsy. In the elderly, the most common
associated conditions are the use of psychotropic drugs, particularly
those with anticholinergic properties, urinary tract infections,
and the presence of an underlying dementing illness in combination
with an acute illness. Rather than a single cause, most patients
have two or more coexisting problems.
particularly psychotropic drugs, deserve special consideration as
causes of delirium. In addition to primary anticholinergic drugs,
many other medications, such as some of the antidepressants, have
anticholinergic properties. Among the neuroleptics, the phenothiazines
have prominent anticholinergic properties that may cause delirium.
Long-acting sedatives, such as chlordiazepoxide and diazepam, and
shorter-acting agents, such as triazolam, temazepam and lorazepam,
may cause delirium. Among the antihypertensives, the central alpha-receptor
blockers and the beta-receptor blockers are associated with the
greatest risk of delirium. Digitalis may cause delirium in the absence
of cardiotoxic effects.
is the Value of Laboratory Testing, Lumbar Puncture, or Electroencephalogram?
testing of delirious patients should include: complete blood count,
electrolyte panel, metabolic panel, thyroid function tests, urinalysis,
electrocardiogram and chest radiograph. CT or MRI Imaging studies
are indicated in patients with a history of or signs of head trauma,
those with focal neurologic symptoms or signs, and those without
a reasonable explanation for delirium. The lumbar puncture is indicated
in the delirious patient in the absence of an apparent precipitant.
Although a lumbar puncture should always be performed when the cause
of delirium is inapparent, many elderly patients with localized
infections, such as a urinary tract infection, develop delirium
without spread of the infection to the central nervous system. The
electroencephalogram may be useful in diagnosing delirium. However,
the electroencephalogram is not pathognomonic of delirium, nor can
it distinguish delirium from dementia. Diffuse slowing can be seen
with either condition. In patients in whom no organic basis for
delirium is apparent, a completely normal EEG would suggest that
the patients symptoms may be due to a functional psychiatric illness.
Should Delirium be Treated?
and nonpharmacologic modalities are equally important in managing
delirium. Of most relevance are (1) the treatment of the specific
underlying illness, (2) general support of fluid and electrolytes,
(3) nonpharmacologic interventions, and (4) the use of psychotropic
medications. First, the physician must determine whether the patient
is critically ill, as reflected by cardiorespiratory status and
level of consciousness. Irregular respiratory patterns, particularly
apneic episodes, and stupor may necessitate intensive cardiac and
respiratory monitoring. All unnecessary medications with potential
adverse effects on the central nervous system must be discontinued.
Infections, which frequently precipitate delirium will require antibiotics
and patients with and fluid and electrolytes will require corrective
presence or absence of nonpharmacologic factors will influence the
course of delirium. Continuity of care provided by staff familiar
to the delirious patient greatly allays agitation. Patients should
be given their eyeglasses and hearing aides, and staff should employ
simple and repetitive instructions regarding tests and other procedures.
Verbal reminders of the setting and time should be used regularly.
Physical restraints, in particular, should be avoided as they may
induce fear and anger, exacerbating motor restlessness. They should
be used only when necessary to facilitate evaluation and treatment.
There will almost never be an indication for all four extremities
to be restrained in the elderly.
should Psychotropics be Used to Treat Delirium?
goals of pharmacologic therapy are to reverse psychotic signs and
symptoms, to stop potentially dangerous behavior, and to calm the
patient sufficiently to conduct the necessary evaluation and treatment.
Unfortunately, there are no controlled clinical studies on which
to base the choice of psychotropic medication for delirious elderly
patients. Well designed clinical trials of psychotropic drugs, particularly
neuroleptics, have been conducted in patients with functional psychoses
and dementia, but not in delirious patients. Nevertheless, clinical
experience and knowledge of the pharmacologic properties of alternative
psychotropic agents provide a rationale for drug selection. First,
no psychotropic medication should be given unless necessary to accomplish
the aforementioned goals. For example, the lethargic delirious patient
with due to a hyperglycemic hyperosmolar state requires fluid and
electrolytes, not a psychotropic medication. Second, medications
with anticholinergic effects should be avoided if possible because
of the cholinergic deficits present in delirium. Thus, chlorpromazine
and thioridazine may cause more harm than benefit in delirious patients.
most instances, the drug of choice is haloperidol or a similarly
potent antipsychotic. Unlike the sedative-hypnotics, haloperidol
is unlikely to oversedate the patient, and its antipsychotic properties
are useful in treating delusions, paranoia, and perceptual disturbances.
The exception to haloperidol use are patients in withdrawal states,
in whom sedative-hypnotics are the drugs of choice.
dose and route of administration of haloperidol are important. Intramuscular
haloperidol reaches peak absorption in 30 to 60 minutes, whereas
the peak absorption after oral haloperidol may be 2 to 6 hours.31
The delayed onset of action may result in patients being given a
second dose of haloperidol or, even more regretfully, another psychotropic
drug before the first dose of haloperidol has had an opportunity
to take effect. Therefore, when haloperidol is used, intramuscular
or intravenous treatment is recommended initially in all but the
mildest case. The dose of haloperidol required in elderly delirious
patients is dictated by the severity of the patient's symptoms.
Although typically doses ranging from 0.5 to 5 mg once or twice
per day are sometimes necessary, the initial dose should be in the
lower range from 0.5 to 2 mg. When oral doses of halperidol are
used, administration of a single dose in the early evening is recommended
to allow for the slow absorption.