Chapter 62. Delirium in the Intensive Care Unit

• Delirium may be considered to be present when there is an acute or fluctuating change in mental status and inattention coupled to disordered thinking or an altered level of consciousness.
• Delirium is extraordinarily common among patient populations in the intensive care unit (ICU) and is under-recognized by care providers, in part related to a previous lack of tools to assess this phenomenon.
• Hypoactive or mixed forms of delirium are more common than pure hyperactive delirium.
• The Confusion Assessment Method for the ICU is a well-validated tool to provide simple and reproducible assessment of delirium at the bedside.
• The risk factors for delirium may be divided into host factors, the acute illness, and environmental or iatrogenic factors.
• Because age and pre-existing mental impairment are powerful risk factors for delirium, it is likely to be encountered with increasing frequency in the ICU in the future.
• Because administration of psychoactive drugs, including sedatives and analgesics, is an important risk factor for delirium, this represents a fruitful area for modification of practice to reduce the incidence of delirium in ICU patients.
• Delirium is independently associated with increased morbidity, cost of care, and mortality rate, even after adjusting for severity of illness, age, coma, and other relevant covariates.

Patients in the intensive care unit (ICU) who experience delirium are exhibiting an under-recognized form of organ dysfunction. Delirium is extremely common in ICU patients due to factors such as comorbidity, critical illness, and iatrogenesis. This neurologic complication can be extremely hazardous in hospitalized older persons and is associated with death, prolonged hospital stays, and institutionalization. Neurologic dysfunction compromises patients' ability to be removed from mechanical ventilation or achieve full recovery and independence. Unfortunately, health care providers in the ICU are unaware of delirium in many circumstances, especially those in which the patient's delirium is manifesting predominantly as the hypoactive (quiet) subtype as opposed to the hyperactive (agitated) subtype. In the past few years, research on ICU delirium has demonstrated the importance of this problem in critically ill patients in addition to methods for routinely monitoring delirium at the bedside. This chapter reviews the definition and salient features of delirium, its primary risk factors, validated methods for bedside delirium assessment, pharmacologic agents associated with the development of delirium, and pharmacologic and nonpharmacologic strategies for delirium management.

Historically, two words were used to describe confused patients. One was the Roman word delirium, which referred to an agitated and confused person (think of hyperactive delirium). The other was from the Greek word lethargus, which was used to describe a quietly confused person (think of hypoactive delirium). ICU patients commonly demonstrate both subtypes as they progress through different stages of their illness and therapy. In either case, the patient's brain is not functioning normally. It therefore makes sense that the original derivation of delirium comes from the Latin word deliria, which literally means to “be out of your furrow.” For greater clarity and to avoid misuse of terms such as dementia and delirium, Table 62-1 lists basic definitions of some common cognitive syndromes.

Health care professionals in the ICU have traditionally used inadequate monitoring devices to detect dysfunction in arguably the most important organ of all, the brain. Delirium, an acute central nervous system (CNS) dysfunction resulting from any number of common insults that ICU patients experience, has largely been overlooked in critical care research until the past few years. Recent discussions of encephalopathy and organ dysfunction secondary to sepsis have not mentioned delirium as one of the clinical manifestations of CNS dysfunction.1,2

The ICU literature often refers to delirium as ICU psychosis,3–8 which represents a potentially dangerous misnomer. The development of delirium often goes unnoticed in the ICU because we think of it as “part of the scenery” or an expected and inconsequential outcome of mechanical ventilation and other therapies. A series of investigations has recently been conducted that provide validated means of detecting delirium by nonpsychiatrists (e.g., internists, nurses, or respiratory therapists). The CNS monitoring instruments and observations from these investigations are leading to a change in the culture and practice in the ICU in which health care providers more closely follow patients for the development of delirium and modify their care to help prevent this potentially disastrous complication. The most recent clinical practice guidelines from the Society of Critical Care Medicine (SCCM)9 have recommended routine (daily) monitoring of delirium in all mechanically ventilated patients, which is discussed later in this chapter.

Delirium is thought to be related to imbalances in the synthesis, release, and inactivation of neurotransmitters that modulate the control of cognitive function, behavior, and mood.8,10 Three of the neurotransmitter systems involved in the pathophysiology of delirium are dopamine, γ-aminobutyric acid, and acetylcholine.11,12 Whereas dopamine increases excitability of neurons, γ-aminobutyric acid and acetylcholine decrease neuronal excitability.11 An imbalance of one or more of these neurotransmitters results in neuronal instability and unpredictable neurotransmission. In general, an excess of dopamine and depletion of acetylcholine are two major physiologic problems felt to be central to delirium. In addition to these neurotransmitter systems, others are thought to be involved in the development of delirium, such as serotonin imbalance, endorphin hyperfunction, and increased central noradrenergic activity.10,12

Several causal factors lead to neurotransmitter imbalance, including reduction in cerebral metabolism, primary intracranial disease, systemic illness, secondary infection of the brain, exogenous toxic agents, withdrawal from substances of abuse such as alcohol or sedative-hypnotic agents, hypoxemia, metabolic disturbances, and the administration of psychoactive medications such as benzodiazepines and narcotics.12,13 Cognitive neuroscience and psychopharmacology are active areas of research that may advance our understanding and treatment of delirium.

There are more than 25 terms in the literature used to refer to delirium, such as “subacute befuddlement” and “toxic confusional state.” Others simply refer to delirium as confusion or neurological impairment. The neurologic literature tends to use the terms delirium to refer exclusively to the hyperactive subtype14 and encephalopathy to refer to hypoactive delirium. These subtypes are discussed in the next section of this chapter. ICU psychosis is a potentially dangerous misnomer that refers to delirious patients who demonstrate increased psychomotor activity and hallucinations (i.e., hyperactive delirium).3–8

The prevalence of delirium in ICU cohort studies has been reported as 20%,15 70%,16 and 80%,17 depending on the characteristics of the patient population and the instrument used. Its incidence is likely to increase in future years as older persons more frequently receive ICU care. Two events that are frequently linked during older patients' ICU course are the need for mechanical ventilation and the development of profound and possibly persistent cognitive impairment.18 Almost every patient in the ICU receives narcotics or benzodiazepines at some point during their stay, yet physicians rarely modify the quantity or dosing intervals of these drugs based on patients' age. Patients on mechanical ventilation are frequently sedated to the point of stupor or coma to improve oxygenation, alleviate agitation, and prevent them from removing support devices. However, age is only rarely factored into complex decisions concerning how to dose these potent medications or when to remove sedatives and liberate patients from mechanical ventilation. The result is that it is now commonplace in the ICU to find that most elderly patients receiving mechanical ventilation are in a drug-induced state of “suspended animation.”19

The subtypes of delirium based upon motor activity are hypoactive, hyperactive, and mixed. Peterson et al recently reported on delirium subtypes from a cohort of 613 ventilated and nonventilated ICU patients in whom delirium was monitored for more than 20,000 observations.20 These investigators found that, among patients who developed delirium, pure hyperactive delirium was rare (<5%), whereas hypoactive and mixed types of delirium were the predominant subtypes (∼45% each). Interestingly, the hypoactive subtype was significantly more common in older than in young patients. The risk factors for and clinical implications of these subtypes are the subject of ongoing investigations.

The period surrounding cessation of sedation represents a typical scenario in the ICU setting in which delirium may be easily recognized or completely missed by clinicians. Patients emerging from the effects of sedation may do so peacefully or in a combative manner. At one extreme are the “peaceful” patients who are often erroneously assumed to be thinking clearly. Delirium in this context is referred to as hypoactive delirium and is characterized by decreased mental and physical activities and inattention.6 Such mental status changes could lead to adverse outcomes such as reintubation, which itself has been shown to increase 10-fold the risk of nosocomial pneumonia and death. In addition, hypoactive delirium is associated with aspiration, pulmonary embolism, decubitus ulcers, and other complications related to immobility.

At the other extreme are agitated or combative patients (i.e., hyperactive delirium) who are at risk not only for self-extubation and subsequent reintubation but also for pulling out central venous access and even falling out of bed. These patients are most often given larger doses of sedatives that commit them to at least another day of mechanical ventilation. This places patients at risk for being left in a cognitively impaired state and on mechanical ventilation unnecessarily.21 Because of this difficult cycle, it is important for health care professionals to avoid overuse of psychoactive medications and to develop better methods of assessing cognitive function, especially during the transition from drug-induced or metabolic coma to wakefulness.

The “quiet,” or hypoactive, delirium is frequently overlooked by physicians and nurses.22–25 Delirium remains unrecognized by the clinician in as many as 66% to 84% of patients experiencing this complication,26,27 and it may be attributed incorrectly to dementia, depression, or just an “expected” occurrence in the critically ill, elderly patient.26 Many clinicians expect delirium to present with agitation or hallucinations, features that are not required for the diagnosis. Other reasons for the lack of recognition of delirium include infrequent cognitive assessments and the fluctuating nature of delirium. The very development of delirium has been associated with fewer interactions and less time spent by nurses and physicians in direct patient care.28,29

It is estimated that the cost of care for those older than 65 years will increase 10-fold over the next three decades.30 These data have been used to argue for limiting ICU care provided to the elderly to conserve resources.31–33 However, a recent report from Angus et al. documented that nearly 60% of all ICU days were incurred by patients older than 65 years.34 In fact, adults younger than 65 had 37 ICU days per year per 1000 person-years versus 240 for those older than 75 years. The incidence of acute respiratory failure requiring mechanical ventilation rises 10-fold from the age of 55 to 85,35 resulting in larger numbers of elderly patients treated in ICUs.36

Because of these age-related demographics and the relation between pre-existing cognitive impairment and development of delirium, clinicians are likely to discover an increased burden of delirium among hospitalized patients across the country.37,38 Advanced age and cognitive decline have been found to lead to decreases in the level of interactions and potentially life-saving therapeutic interventions from clinicians and caregivers.39,40 Nevertheless, more and more elderly patients are being admitted to the ICU,41 and certainly this will include older patients with pre-existing cognitive impairment ranging from mild to overt dementia. In a cohort investigation, Pisani et al studied the effect of pre-existing cognitive impairment (mostly mild) on ICU outcomes and found that those with and without cognitive impairment had similar outcomes in terms of length of stay in the ICU and the hospital and mortality rate.42 However, the persistence of delirium symptoms in such patients could strongly affect discharge rates to nursing homes after hospitalization.24,26

Reports have associated CNS organ dysfunction with complications of mechanical ventilation, including aspiration, nosocomial pneumonia, reintubation, and self-extubation.43–47 Moreover, in mechanically ventilated neurosurgical patients, the strongest predictor of failed extubation was found to be an abnormal Glasgow Coma Score.48 In medical ICU patients, Salam et al found important interactions between cognitive dysfunction and the likelihood of failed extubation.49 CNS “failure” is an important predictor of outcome from sepsis.2

In non-ICU populations, the development of delirium in the hospital is associated with an in-hospital mortality rate of 25% to 33%, prolonged hospital stay, and three times the likelihood of discharge to a nursing home.18,24,50 In a three-site study of medical non-ICU patients, delirium was found to be an independent predictor of the combined outcome of death or nursing home placement.51 Francis and Kapoor found that the 2-year mortality rate in patients having experienced delirium was 39% versus 23% in controls,52 but multivariate analysis showed that this was largely explained by baseline cognitive and functional statuses. Perhaps the most convincing report of the independent association between delirium and mortality rate among non-ICU patients was published by McCusker et al,53 which showed an adjusted hazard of dying of 2.11 associated with the development of delirium. This mortality rate increase has since been shown to be independent of dementia status.54

Among ICU patients, there is current evidence that delirium is a predictor of mortality at 6 months following the ICU stay (Fig. 62-1).55 The development of delirium was associated with a threefold increase in risk of death after controlling for pre-existing comorbidities, severity of illness, coma, and the use of sedative and analgesic medications. These data also showed that delirium is not simply a transition state from coma to normal because delirium occurred just as often among those who never developed coma as among those who did and persisted in 11% of patients at the time of hospital discharge. Further, three recent prospective studies have associated delirium with an increased risk for dementia over 2 to 3 years.56–58 In light of these findings, future studies should determine whether or not prevention or treatment of delirium changes clinical outcomes, including mortality rate, length of stay, cost of care, and long-term neuropsychological outcomes among survivors of critical illness.

Delirium complicates the hospital stay of more than 2 to 3 million elderly patients per year in the United States, involving more than 17.5 million inpatient days and accounting for more than $4 billion in Medicare expenditures.59 In the only study to date reporting on costs associated with delirium in the ICU, Milbrandt et al found that median ICU and hospital costs were significantly higher for those with at least one episode of delirium versus those with no delirium (Fig. 62-2).60 Even after controlling for important potentially confounding variables, such as baseline comorbidities and severity of illness, delirium was associated with a 40% relative increase in ICU and total hospital costs. In addition, the data demonstrated a “dose-response” in which cumulative delirium severity was associated with incrementally higher cost.

The associated annual cost of ICU delirium may be enormous. In the study by Milbrandt et al,60 delirium occurred in 82% of mechanically ventilated patients and was associated with an incremental increase in ICU cost of more than $9000 per patient. In the United States, there are approximately 880,000 to 2,760,000 ICU admissions annually for respiratory failure requiring mechanical ventilation. Therefore, the estimated number of cases of ICU delirium may range from 721,600 to 2,263,200 per year, with an associated increase in health care costs ranging from $6.5 billion to $20.4 billion. Even if the incidence of delirium from a less severely ill ICU cohort occurred in only 19% of patients,61 the estimated annual costs would be in the range of $1.5 billion to $4.7 billion. Because some of the additional cost associated with delirium could be attributable to unmeasured differences between patient groups, these estimates represent the upper limit of the cost attributable to ICU delirium. However, even if only 20% of the difference in costs between patients with and without delirium were due to delirium, this would be a significant public health concern, with $300 million to $4 billion in annual attributable costs.

Only a few studies of ICU patients have studied risk factors for delirium, although many investigations over the past decade, by using a variety of non-ICU cohorts, have identified numerous risk factors for the development of delirium.50 Patients who are highly vulnerable to delirium may develop the disorder after only minor physiologic stressors, whereas those with low baseline vulnerability require a greater insult to become delirious.62 It is possible to stratify patients into risk groups depending on the number of risk factors present.26,62–64 Three or more risk factors increase the likelihood of developing delirium to approximately 60% or higher, and it is a rare patient in the ICU who would not be in the high-risk group. Most ICU patients have more than 10 risk factors for delirium.17,65

In practical terms, the risk factors can be divided into three categories: (1) host factors, (2) the acute illness, and (3) iatrogenic or environmental factors (Table 62-2).4,18,23,26,61,63,64,66–68 Issues that are ripe for study in terms of prevention or intervention have been indicated. In the only ICU cohort risk factor study published to date,61 factors related to medical history included hypertension and smoking (thereby raising one's awareness of the risks of relative underperfusion of the brain or nicotine withdrawal). During the ICU stay, a dose-dependent risk was found for patients having been treated with opiates.

Psychoactive medications are the leading iatrogenic risk factors for delirium.24,61,62,69,70 Benzodiazepines, narcotics, and other psychoactive drugs are associated with a 3 to 11 times increased relative risk,24 and the number and rate of adding psychoactive medications increase the risk of delirium by 4 to 10 times.24 By coupling these data to knowledge regarding the extreme variability in the pharmacokinetics of sedatives and analgesics according to age, ethnicity, drug metabolizing ability and other factors,71–74 perhaps the most promising delirium interventions could be centered on delivery patterns of these medications.

The SCCM guidelines suggest that all critically ill patients be simultaneously monitored for level of sedation and for delirium.9 Bedside critical care nurses and the rest of the ICU team need to use data obtained from well-validated, reliable, objective, but brief assessment tools to monitor for both components of consciousness (arousal level and content of consciousness).75 Neurologic monitoring in the ICU can be streamlined by using a two-step approach to sedation and delirium.

The first step in the neurologic assessment of an ICU patient is to assess that patient's level of consciousness or sedation with an objective sedation assessment. The recommended standard of care is to use objective assessment scales to avoid oversedation and to promote earlier liberation from mechanical ventilation.9,76–80 Sedation scales help provide a common language for the multidisciplinary team to use when discussing goals and treatments for patients.80–82 Whereas the Ramsay Scale83 has been the most widely used instrument for decades in clinical practice and the published literature,84 other recently developed instruments such as the Sedation-Agitation Scale85 and Richmond Agitation Sedation Scale86,87 have been better validated and are being widely implemented.17,88 Chapter 14 includes a thorough discussion of how to approach sedation in the ICU, but it is appropriate to emphasize the importance of using these instruments to guide patient-targeted or goal-directed sedation. The concept of using sedation scales over time within patients was addressed in the second Richmond Agitation Sedation Scale validation study,87 in which emphasis was placed on the fact that potent psychoactive medications should not be given without a specific agreed-on target level of effect.

The second step for assessing the brain's function in critically ill ICU patients builds on the level of arousal assessment and involves the delirium assessment. All patients who are responsive to verbal stimuli should be assessed for delirium. The first delirium assessment tools designed specifically for nonverbal, intubated ICU patients were published in 2001.15,17,89 One of these instruments is the Intensive Care Delirium Screening Checklist,15 which is used as a screening instrument due to its high sensitivity (99%) and moderate specificity (64%). The other is the Confusion Assessment Method for the ICU (CAM-ICU),17,89 which has a sensitivity and specificity of approximately 95% and very high interrater reliability (κ = 0.96). The CAM-ICU was designed to be a serial assessment tool for use by bedside clinicians (nurses or physicians). Thus, it is easy to use, takes only 1 minute on average to complete, and requires minimal training. Delirium assessment using the CAM-ICU incorporates four key features that comprise delirium as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (American Psychiatric Association). These features are (1) change in mental status from baseline or fluctuating course of mental status, (2) inattention, (3) disorganized thinking, and (4) altered level of consciousness. Delirium is present when features 1 and 2 plus features 3 or 4 are present (Fig. 62-3 and Table 62-3). The CAM-ICU has been translated into many languages, and numerous aspects of neurologic monitoring are discussed and available for download from an educational Web site (http://www.icudelirium.org).

Primary Prevention and Nonpharmacologic Approaches

In a trial of 852 general medical patients older than 70 years,90 strategies for primary prevention of delirium resulted in a 40% reduction in the odds of developing delirium (15% in controls versus 9.9% in the intervention patients). The protocol focused on optimization of risk factors with the following methods: repeated reorientation of the patient by trained volunteers and nurses, provision of cognitively stimulating activities for the patient three times per day, a nonpharmacologic sleep protocol to enhance normalization of sleep and wake cycles, early mobilization activities and range of motion exercises, timely removal of catheters and physical restraints, institution of the use of eyeglasses and magnifying lenses, hearing aids and earwax disimpaction, and early correction of dehydration. Unfortunately, this intervention did not show sustained benefit when the patients were followed to 6 months.91 Other recent studies of delirium prevention reproduced success only in subgroups such as those without underlying dementia92 or not at all.93

However, this study of primary prevention did not focus on critically ill patients and excluded mechanically ventilated patients. Because ICU studies using the CAM-ICU have documented delirium rates of 70% to 80%, one might view the “room for improvement” in delirium management as far greater for critically ill patients than for general medical patients. Although primary prevention of delirium is preferred, some degree of delirium is inevitable in the ICU. In these cases, the basic tenets of patient management such as restoring sleep/wake cycles, timely removal of catheters, early mobilization, use of a scheduled pain management protocol, minimization of unnecessary noise or stimuli, and frequent reorientation should be applied liberally. Family involvement can be very helpful in reorienting and soothing delirious patients. It is important to teach family members about the fluctuating course of delirium and how they can detect delirium. Preventive and management strategies for delirium in the ICU represent an important area for future investigation.

Pharmacologic Therapy

Medications should be used only after giving adequate attention to correction of modifiable contributing factors (e.g., sleep disturbance and restraints) as discussed above and presented in Table 62-2. It is important to recognize that delirium may be a manifestation of an acute, life-threatening problem that requires immediate attention (e.g., hypoxia, hypercarbia, hypoglycemia, metabolic derangements, or shock). After addressing such concerns, delirious patients should be considered for pharmacologic management. Even though the agents used to treat delirium are intended to improve cognition, they all have psychoactive effects that may further cloud the sensorium and promote a longer overall duration of cognitive impairment. Therefore, until outcomes data confirm the beneficial effects of treatment, these drugs should be used judiciously in the smallest possible dose and for the shortest time necessary, a practice infrequently adhered to in most ICUs. Some patients will prove refractory to all “cocktail” approaches to sedation and delirium therapy, and these patients should be considered for a trial of complete cessation of all psychoactive drugs.

Benzodiazepines, which are used most commonly in the ICU for sedation, are not recommended for the management of delirium because of the likelihood of oversedation, exacerbation of confusion, and respiratory suppression. However, they remain the drugs of choice for the treatment of delirium tremens (and other withdrawal syndromes) and seizures. The amnestic qualities of benzodiazepines make these agents especially useful when noxious or unpleasant procedures are required. However, it is likely that residual accumulation of these drugs may lead to prolonged delirium long after the drugs have been discontinued. In certain populations, in particular elderly patients with underlying dementia, benzodiazepines may lead to increased confusion and agitation. In such cases, one may try to take advantage of the sedative effects of haloperidol in lieu of continued benzodiazepines. Preliminary results from a prospective, randomized, but unblinded trial of sedation in postoperative cardiac surgical patients showed that those treated with dexmedetomidine, as opposed to propofol or midazolam, were less likely to develop delirium.94 This work must be confirmed on a larger scale with documented improved outcomes before modifying standard sedation practices.

There are currently no drugs approved by the U.S. Food and Drug Administration for the treatment of delirium. The SCCM guidelines recommend haloperidol as the drug of choice, although it is acknowledged that this is based on sparse outcomes data from nonrandomized case series and anecdotal reports (i.e., level C data).9,95–103 Nevertheless, haloperidol is a butyrophenone “typical” antipsychotic, which is the most widely used neuroleptic agent for delirium.104 It does not suppress the respiratory drive and works as a dopamine receptor antagonist by blocking the D2 receptor, which results in treatment of positive symptomatology (hallucinations, unstructured thought patterns, etc.) and produces a variable sedative effect.105

In the non-ICU setting, the recommended starting dose of haloperidol is 0.5 to 1.0 mg orally or parenterally, with repeated doses every 20 to 30 minutes until the desired effect is achieved. In the ICU setting, a recommended starting dose is 5 mg every 12 hours (intravenously or orally), with maximal effective doses usually in the neighborhood of 20 mg/day. This dose range is usually adequate to achieve the “theoretically optimal” 60% D2 receptor blockade106–108 and avoid complete D2 receptor saturation associated with the adverse effects cited below. Because of the urgency of the situation in many ICU patients, due to the potential for inadvertent removal of central lines, endotracheal tubes, or even aortic balloon pumps, much larger doses of haloperidol are often used. Unfortunately, there are few data from formal pharmacologic investigations to guide dosage recommendations in the ICU. Once calm, the patient can usually be managed with much smaller maintenance doses of haloperidol.

Neither haloperidol nor similar agents (i.e., droperidol and chlorpromazine) have been extensively studied in the ICU.9 Newer “atypical” antipsychotic agents (e.g., risperidone, ziprasidone, quetiapine, and olanzapine) may also prove helpful for delirium.9,109 The rationale behind the use of atypical antipsychotics over haloperidol (especially in hypoactive/mixed subtypes of delirium) is theoretical and centers on the fact that they affect not only dopamine but also other potentially key neurotransmitters such as serotonin, acetylcholine, and norepinephrine. Adequately powered randomized controlled trials of these agents are not available.

Adverse effects of typical and atypical antipsychotics include hypotension, acute dystonias, extrapyramidal effects, laryngeal spasm, malignant hyperthermia, glucose and lipid dysregulation, and anticholinergic effects such as dry mouth, constipation, and urinary retention. Perhaps the most immediately life-threatening adverse effect of antipsychotics is torsades de pointes,110,111 and these agents should not be given to patients with prolonged QT intervals unless thought to be absolutely necessary. Patents who receive substantial quantities of typical or atypical antipsychotics or coadministered arrhythmogenic drugs should be monitored closely with electrocardiography. Having mentioned these potential difficulties, antipsychotics (most experience having been accrued with haloperidol) are usually well tolerated from the hemodynamic and respiratory standpoints.

Critically ill patients are at great risk for the development of delirium in the ICU. However, this form of brain dysfunction is grossly under-recognized and undertreated. Delirium is mistakenly thought to be a transient and expected outcome in the ICU and of little consequence (i.e., part of the “ICU psychosis”). It is now recognized that delirium is one of the most frequent complications experienced in the ICU; even after adjusting for covariates such as age, sex, race, and severity of illness, delirium is an independent risk factor for prolonged length of stay and higher 6-month mortality rates. In addition, many ICU survivors demonstrate persistent cognitive deficits at follow-up testing months to years later. It is essential for health care professionals to be able to recognize delirium readily at the bedside. The CAM-ICU is a valid, reliable, quick, and easy-to-use serial assessment tool for monitoring delirium in ventilated and nonventilated ICU patients. Delirium is a multifactorial problem for ICU patients that demands an interdisciplinary approach for assessment, management, and treatment. Critical care nurses and physicians should assume a position of leadership in the ICU with regard to delirium monitoring because they are the best-suited members of the ICU team to successfully implement this essential component of patient management, which is now recommended by the SCCM clinical practice guidelines. Although ongoing trials may elucidate the optimal ways to treat delirium, standard pharmacologic and nonpharmacologic management strategies have been reviewed.

Dr. Ely is the Associate Director of Research for the VA Tennessee Valley Geriatric Research and Education Clinical Center. He is a recipient of the Paul Beeson Faculty Scholar Award from the Alliance for Aging Research and a recipient of a K23 from the National Institute of Health (grant AG01023-01A1).