Delirium in the Intensive Care Unit

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Crit Care Nurs Q
Vol. 26, No. 3, pp. 172–178
c○ 2003 Lippincott Williams & Wilkins, Inc.
Delirium in the Intensive
Care Unit
Margaret Cole Marshall, MS, MA, APRN, BC;
Mark D. Soucy, PhD, APRN, BC
Delirium in the intensive care unit (ICU) is a complex, common, and problematic condition that
interferes with healing and recovery. It leads to higher morbidity and mortality and extended hospital
stays. The aging population older than 65, and more likely to develop delirium, is the fastest
growing population in the United States and is increasingly seen in the ICU. Delirium is often unrecognized
and misdiagnosed, which leads to mistreatment or lack of appropriate treatment. This
article discusses the definition of delirium, pathogenesis, clinical practice guidelines, newer assessment
tools for ICU, and nursing interventions directed toward prevention and early identification
of delirium. Key words: assessment tools, critical care patient, delirium, nursing interventions,
pathogenesis, prevention, risk factors
WHILE all patients in the intensive care
unit (ICU) have very serious and lifethreatening
conditions, those with advanced
age bring with them additional challenges
as they experience physiological changes related
to growing older. Older patients in the
ICU environment, having special procedures,
following anesthesia and surgical interventions,
all have a risk for delirium, which results
in a poorer prognosis and an extended
hospital stay as well as an increased financial
burden. 1
This article defines delirium and will address
its pathogenesis, types of delirium and
behavior manifested related to the type of
delirium, prodromal symptoms, risk factors,
preventive measures, nursing interventions,
and assessment tools.
From the Department of Family Nursing Care, School
of Nursing, University of Texas Health Science Center,
San Antonio, TX.
Corresponding author: Margaret Cole Marshall, MS, MA,
APRN, BC, Department of Family Nursing Care, School
of Nursing, University of Texas Health Science Center,
7703 Floyd Curl Dr, MC 7951, San Antonio, TX 78229–
3900 (e-mail: PeggyMarshall@bigplanet.com).
172
DEFINITION OF DELIRIUM
Delirium in the ICU is a common and problematic
condition that leads to higher morbidity
and mortality and extended hospital
stays. 2,3 Delirium is a condition that can be
either unrecognized or misdiagnosed. 1,2,4–6,7
Eli and colleagues 8 report that 66% to 84%
of delirium in elderly hospitalized patients is
unrecognized by clinicians, and that 94% of
patients demonstrated the hypoactive type.
Delirium has been described as a sundown
syndrome, ICU psychosis, acute confusion,
ICU syndrome, encephalopathies, and cognitive
impairment. Thirty percent of patients in
surgical ICUs and 40% to 50% of patients after
hip surgery manifest delirium. Three months
after a patient is diagnosed with delirium, a
mortality rate between 23% and 33% is documented.
In a 1-year follow-up, there was up
to 50% mortality rate of patients diagnosed
with delirium. 9 Up to 60% of older hospitalized
patients develop delirium as a complication
during their hospital course. Delirium is
listed as a target for quality of care improvement
for the elderly population. 8 As the population
ages, more ICU beds are filled by elderly
patients requiring risk assessment and
early intervention. 1

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Delirium can manifest in 2 varieties, hyperactive
and hypoactive. Advanced age has been
identified as a risk factor. Those who have a
better premorbid cognitive and physical condition
recover or have a more favorable outcome.
Delirium is seen as an abrupt cognitive
decline from a previous level of functioning
due to a medical condition and/or a substance.
“A delirium is characterized by a disturbance
of consciousness and a change in
cognition over a short period of time.” 10 Although
the same symptom presentation is
seen, delirium is diagnosed based on etiology:
Delirium due to a general medical condition,
substance-induced delirium, delirium due to
multiple etiologies, and delirium not otherwise
specified (NOS) when the etiology is
undetermined. The disturbance of consciousness
and cognition must not be associated
with a developing dementia. 10
SYMPTOMS OF DELIRIUM
Delirium is indicative of cerebral dysfunction.
The beginning stages of this process
are seen in the prodromal symptoms. These
symptoms include anxiety, restlessness, insomnia,
and disturbing dreams and these usually
start at night. The 2 types of delirium
are hypoactive and hyperactive. Patients can
have a mixture of both types, which means
that at one point they can appear hypoactive,
and then at another point appear to
be hyperactive. Hypoactive delirium includes
slowed speech, slowed movements, sluggishness,
apathy, depression, and lethargy. Hyperactive
delirium includes excessive activity,
rapid pressured speech, rage, fear, rapid
movements, and increased reaction to any
stimuli. 4 The hypoactive type may not be recognized
as they appear to not present the
physical danger of injury that the hyperactive
type does.
The symptoms start abruptly with changes
in level of consciousness and awareness
fluctuating, including impaired attention,
with distractibility. Cognition changes include
memory problems, disorientation, and rambling
or incoherent speech, while percep-
Delirium in the Intensive Care Unit 173
tual difficulties are manifested in hallucinations,
particularly visual ones. Other disturbances
include sleep-wake cycles, rapid shifts
in emotions, fear, anger, irritability, and depression.
When the underlying medical condition
is not treated, death can result. Medically
ill patients who develop delirium are more
at risk for medical complications and significant
morbidity. 11 A number of reasons why
delirium is misdiagnosed in the ICU have been
identified by Armstrong. 1 These include the
following: (1) it is an expected event in the
ICU and so it is not identified, (2) it is seen
as secondary to other issues in the ICU and
therefore may be overlooked, 1 (3) women are
identified as depressed when seen (probably
delirium, hypoactive type) and men are given
“no diagnosis” as it is easier to label women
than men in this setting. Trzepacz 12 reports
that the nonpsychiatric literature is less specific
about criteria and have included dementia
as part of the delirium category.
Confusion
Confusion is a group of behaviors, including
inattention and memory difficulties: disruptive
behaviors such as aggressiveness, combativeness,
and delusions, with an inability
to perform activities of daily living. It is a
nonspecific term. 13 Confusion and disorientation
are 2 different cognitive components.
Disorientation refers to place, person, and
time. Confusion includes alterations in memory,
judgment, decision making, and problem
solving. 13 In the elderly, confusion can be
seen as symptomatic of delirium or depression.
Confusion may also be seen in major
depression and psychoses. Treating the underlying
physical disorder can reverse or eliminate
the delirium whether it is related to a
urinary tract infection or perhaps an adverse
drug reaction. 14
Agitation and anxiety
From a medical standpoint, agitation appears
to be viewed in a different light than
from a psychiatric perspective. Agitation is

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174 CRITICAL CARE NURSING QUARTERLY/JULY–SEPTEMBER 2003
seen as important because in the critical
care area it very often leads to posttraumatic
stress disorder, delirium, and post-ICU depression.
Agitation is now receiving more attention
as an important area in ICUs. Agitation
is seen as both increased violent movement
and strong emotion. 15 It is characterized by
restlessness, fidgeting, attempts at removing
dressings, catheters and other tubes, disorientation,
inattention, and inability to follow
commands. 15 This agitation produces abnormal
vital signs, with blood pressure, respirations,
and pulses rising to dangerous levels.
Multiple causes are seen as producing agitation,
including anxiety, delirium, pain, confusion,
and withdrawal. Agitation is seen as a
result of hypoxia, drugs, inadequate pain management,
hypotension, brain injury, anxiety,
and the ICU environment with its accompanying
noise, bright lights, and other continuous
stimuli. 15 Delirium is seen from a medical
standpoint as uncontrolled agitation. Delirium
found in the ICU is in 15% to 40% of ICU
patients and results in a poorer prognosis and
a significant mortality rate of 10% to 33%. 15
Agitated behavior as seen in delirium is problematic
as these patients self-extubate and remove
catheters, leading to increased morbidity,
mortality, and length of stay. 16
PATHOGENESIS
Delirium is considered as a dysfunction
in multiple brain regions. As yet, underlying
pathogenesis is still unclear. 12 Trzepacz states
that since a variety of etiologic factors can
give rise to delirium, it is a syndrome rather
than a disease. Trzepacz identifies some of the
subtypes as hyperactive vs hypoactive, cortical
vs subcortical, anterior vs posterior cortical,
right vs left hemispheric, psychotic vs
nonpsychotic, and acute vs chronic. Certain
drug withdrawals such as alcohol or barbituates
and those that can induce anticholinergic
toxicity produce a hyperactive type of
delirium. Certain metabolic dysfunctions such
as hepatic insufficiency produce a hypoactive
delirium. Brain metabolism may be primary
to this process of delirium and altered
neurotransmitters may be secondary or re-
sults from interference in brain metabolism. 12
Multiple hypotheses have been suggested as
causative for delirium. Engel and Romano
concluded a reduction in cerebral oxidative
metabolism as causative for cognitive impairment.
Any disease or toxic agent capable of reducing
the supply or utilization of substrates
for brain metabolic activity could produce
delirium. Blass and Plum took that hypothesis
a step further and stated that a reduced
rate of cerebral oxidative metabolism reduces
acetylcholine synthesis resulting in cholinergic
deficiency and thus leads to delirium. Itil
and Fink postulate that reduced cerebral oxidative
metabolism and reduction in specific
neurotransmitters, namely acetylcholine, is
pathogenic to this process. Kral’s view states
that acute confusional states in the elderly are
a reaction to stress with elevated levels of
cortisol and deleterious effects on anatomical
substrates of attention and information processing.
Last, Geschwind’s hypothesis is that
confusional states are global disorders of attention
and the result of acute lesions in the
anatomical substrates of attention. 4
On a continuum, the first behavior observed
is anxiety. Anxiety is a subjective
emotional experience noted by apprehension
and observed by objective symptoms of autonomic
system arousal. 16 This manifests in
restlessness. This then escalates to confusion
and agitation. If not addressed early, it becomes
a full-blown case of delirium. For some
patients, subclinical delirium or prodromal
symptoms may be observed for 1 to 3 days
before full criteria are met for delirium. These
symptoms are restlessness, anxiety, irritability,
distractibility, and sleep disturbances. 11 The
night nurse may be the first person to notice
a change in mental status and sleep pattern because
of a disturbance in the wake-sleep cycle
and sundowning phenomena. Sundowning
is observed when a patient may be alert
and oriented during the day, but as the sun
goes down, the patient becomes confused
and disoriented. 17,18 “There are many roads to
decompensation for an impaired brain.” 19 The
earlier the identification and intervention into
changes in dysfunctional behavior, a more favorable
outcome can be accomplished.

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CAUSATIVE AND RISK FACTORS FOR
DELIRIUM
A number of organic causative factors
for delirium have been determined: primary
cerebral diseases, which include infections,
stroke, and trauma, systemic disease that affect
the brain, which are metabolic diseases,
infections, and cardiovascular disease, intoxication
with exogenous substances, such as
drugs, and withdrawal from substances of
abuse, alcohol, and sedative-hypnotic drugs. 4
Delirium is a common mental disorder encountered
in general hospital practice with
the elderly as the elderly are more at risk
for delirium. 20 In those patients older than
70, 30% to 50% show signs of delirium while
hospitalized. In the elderly, delirium can be
the presenting symptom of acute physical
illness, and if not recognized, can lead to
death. The elderly are more prone to this
disorder because of the effects of aging, disease
of the brain, reduced neurotransmitters,
particularly acetylcholine, reduced vision and
hearing, chronic diseases, sleep deprivation,
stress, and failure to adapt to residing in unfamiliar
environments. 4
In the elderly, there can be multiple factors
that play a role in the development of delirium.
Because those older than 65 years usually
have other medical conditions, they are
usually on at least 6 to 8 medications before
coming into the hospital. These drugs may
include agents such as digoxin, antiparkinsonian,
antipsychotics, antidepressants, diuretics,
and sedative-hypnotics. Polypharmacy
and drug interactions can induce delirium.
Physical conditions that induce delirium include
congestive heart failure, pneumonia,
urinary tract infections, cancer, uremia, dehydration,
sodium depletion, and cerebral
infarction. 4
CLINICAL PRACTICE GUIDELINES
Several groups describe clinical practice
guidelines in the critical care area to ensure
best practice. Clinical practice guidelines are
usually created by a multidisciplinary group of
clinicians using scientific literature for guiding
Delirium in the Intensive Care Unit 175
decision making. The Institute of Medicine,
Society of Critical Care Medicine (SCCM),
American College of Critical Care Medicine
(ACCM), and the American Psychiatric Association
(APA) all have guidelines. For instance,
pain is a serious issue with critically ill patients.
Patients experiencing pain may manifest
restlessness, agitation, and confusion.
Guidelines for pain management address sedation,
analgesia, and neuromuscular blockade
in the ICU. Assessment of pain is very important
and needs to be done on a regular
basis. “The restlessness associated with critical
illness must nearly always, by necessity, be
quelled with sedation and analgesia.” 21 Maintaining
comfort and safety for the critically ill
patient, particularly those on mechanical ventilation,
is a central goal. 22
Practice guidelines for the treatment of patients
with delirium are also published by
APA. 10 These guidelines provide (1) immediate
interventions for urgent medical conditions,
(2) identification and treatment of
delirium, (3) means to ensure safety, and (4)
suggestions to improve the patient’s functioning.
These include environmental and supportive
interventions. Somatic interventions
include making recommendations for medication,
using haldol and droperidol 23 as the
most frequently used, but other antipsychotic
drugs may also be recommended. Under the
guidelines for monitoring and ensuring safety,
the patient must be evaluated for suicidal and
violent potential in order to protect the patient
and others. Restraints are not recommended
as they can increase agitation and
injury to the patient and they must only be
used as a last resort for patient safety in a limited
fashion. These patients require close observation
by caregivers. The nurse needs to
assess risk for falls and self-harm. Since symptoms
in patients with delirium fluctuate, frequent
monitoring is needed to assess for agitation,
aggressive behavior, sleep disturbances,
delusions, and hallucinations. Treatment is determined
by the manifest behaviors of the
patient. Mental status assessments are done
frequently (at least once a shift) to assess fluctuations,
or to see if symptoms are abating, resolving,
or getting worse. 11

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ASSESSMENT TOOLS
Formal assessment tools used in the ICU
for delirium include Hart’s Cognitive Test for
Delirium, the Abbreviated Cognitive Test for
Delirium, Dr. Inouye’s Confusion Assessment
Method (CAM), and the updated version
specifically for ventilator-dependent patients,
Dr. Ely’s CAM-ICU. 24 The importance of a
nonpsychiatric clinician (nurses) able to administer
the CAM and CAM-ICU in under 5
minutes is a plus. The CAM is used for patients
who can respond verbally. The CAM-ICU involves
showing pictures instead of conversation,
which is necessary for patients on mechanical
ventilators. The 4 areas covered are
acute onset or fluctuating course, inattention,
disorganized thinking, and altered levels of
consciousness. 8,25 Another test using nonverbal
measures that reflects impaired cognition
is the behavioral rating scale called the Clinical
Assessment of Confusion-A (CAC-A). 26 All
tools test for orientation, observing if there is
a change in behavior or alertness, lethargy, or
agitation, and observing if the patient is attentive
and can follow commands are the other
categories tested. Disorganized thinking is assessed
by observing if the patient speaks incoherently,
is rambling, or indulges in irrelevant
conversation.
When a patient is admitted to the ICU, nursing
assessment includes taking a history of
medical and psychiatric conditions. For instance,
does the patient, if older than 65 years,
have the beginning stages of dementia, which
puts him or her at increased risk for delirium?
What medications have they been taking,
including a history of herbal and over-thecounter
medications? Herbal medicines have
the potential for polypharmacy and drug interactions
that can cause morbidity and mortality
during the perioperative period. 27 Often
overlooked is a history of alcohol abuse and
when was the last drink. Alcohol is the most
common substance abused by the elderly,
along with prescription drugs of a sedativehypnotic
and anxiolytic type. Polypharmacy
puts patients at risk for drug interactions
and confusion. 13 Assess the patient’s baseline
mental status. In the ICU, delirium usually develops
over 2 to 3 days, and so observing and
documenting baseline behavior that reflects
cognitive status is important. What are the
changes in their life and what are the recent
adjustments or adaptations they have had to
make?
NURSING INTERVENTIONS
Nursing management first starts with looking
for and recognizing symptoms of delirium,
particularly those at risk. Preventive measures
can be implemented by the nurse, observing
and assessing patients frequently for changes
in mental status or behavior and checking to
see if the patient is oriented to person, time,
and place. 7
Patients coming into the ICU are often
frightened, confused, in pain, and fearful. It
is important for the nurse to be with the patient,
identify oneself, and explain to the patient
and family about each procedure and
what to expect. The nurse must educate the
family that when delirium occurs it is a temporary
condition and that it will improve after
treatment. The nurse must give frequent
reassurance. Identifying and being aware of
the patient’s level of anxiety (which should be
monitored for increasing levels) is important.
28,29 It is known that when anxiety gets
high enough, it can progress to delirium. As
much as possible, decrease all noise levels
so as to help the patient get proper sleep;
rest is particularly needed. This may mean
keeping TVs off, staff speaking softly, and
turning lights down. Prevention will also include
tracking laboratory and physical parameters
(along with monitoring nutritional
intake), and as well as ensuring adequate hydration,
safety, and pain management. There
are a number of guidelines that make recommendations
for treatment of delirium. Once
delirium is identified, an immediate search
must begin to identify contributing physical
factors and correct them.
When a patient becomes agitated, the plan
of care is adjusted to accommodate the
change. Delirium complicates the medical

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picture to give care, especially if the patient
is agitated, uncooperative, hallucinating, and
disoriented. Patients, at this time, may be unable
to participate appropriately in their own
care. Delirium is more visible and problematic
at night because of the wake-sleep cycle
disturbance. 30 When nonpharmacologic measures
and reassurance are not adequate, then
administering medication would be the next
step. Haldoperidol or another antipsychotic
is usually ordered by the clinician and the
nurse administers the medication and documents
the response. Medications of this type
are considered a form of chemical restraint to
prevent the patient from self-injury or other
unsafe behaviors, such as pulling out tubes or
catheters. One on one observation is needed
at this time to keep the patient safe. Avoid using
physical restraints except as a last resort.
Restraints increase the patient’s anxiety and
the patient may sustain injuries from restraint
devices. 17
SUMMARY
Delirium is a complex condition as it is multifaceted
and can present in different ways.
Misdiagnosis or missed diagnosis can complicate
treatment and recovery. Delirium in the
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Delirium in the Intensive Care Unit 177
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