Subsyndromal delirium in the ICU: evidence for a disease spectrum

Diagnostic considerations regarding pediatric delirium: a review and a proposal for an algorithm for pediatric intensive care units

CONTEXT

If delirium is not diagnosed, it is unlikely that any effort will be made to reverse it. Given evidence for under-diagnosis, tools that aid recognition are required.

OBJECTIVE

Relating three presentations of pediatric delirium (PD) to standard criteria and developing a diagnostic algorithm.

RESULTS

Delirium-inducing factors, disturbance of consciousness and inattention are common in PICU patients: a pre-delirious state is present in most. An algorithm is introduced, containing (1) evaluation of the sedation-agitation level, (2) psychometric assessment of behavior and (3) opinion of the caregivers.

DISCUSSION

It may be argued that the behavioral focus of the algorithm would benefit from the inclusion of neurocognitive measures.

LIMITATIONS

No sufficiently validated diagnostic instrument covering the entire algorithm is available yet.

CONCLUSION

This is the first proposal for a PD diagnostic algorithm. Given the high prevalence of predelirious states at the PICU, daily evaluation is mandatory. Future algorithmic refinement is urgently required.

Validity and reliability of the CAM-ICU Flowsheet to diagnose delirium in surgical ICU patients

PURPOSE

Delirium occurs frequently in critical care but often remains undiagnosed because delirium monitoring is often dismissed as being too time-consuming. This study determined the validity and reliability of the "CAM-ICU Flowsheet," a practical, time-sparing algorithm to assess the 4 delirium criteria in intubated patients.

MATERIALS AND METHODS

With permission from our institution's ethics committee, patients of a 31-bed surgical intensive care unit department were screened for delirium (1) by a psychiatrist as the reference rater using the 4 delirium criteria of the Diagnostic and Statistical Manual of Mental Diseases, Fourth Edition (DSM-IV), and (2) by 2 physician investigators using a German translation of the CAM-ICU Flowsheet.

RESULTS

Fifty-four surgical ICU patients underwent the complete protocol assessment with paired observations; 46% were diagnosed with delirium by the reference rater (n = 25), 9% had hyperactive delirium (n = 5), and 37% were hypoactive (n = 20). The CAM-ICU Flowsheet investigators had sensitivities of 88% (95% confidence interval, 69%-98%) and 92% (74%-99%), specificities of 100% (85%-100%), very high interrater reliability (kappa, 0.96; 0.87-1.00), and needed 50 seconds (interquartile range, 40-120 seconds) in patients with delirium vs 45 seconds (interquartile range, 40-75 seconds) in those without delirium to complete assessments.

CONCLUSIONS

The CAM-ICU Flowsheet has high sensitivity, high specificity, and very high interrater reliability. False-negative ratings can occur infrequently and mostly reflect the fluctuating course of delirium. The CAM-ICU Flowsheet is a valid, reliable, and quickly performed bedside delirium instrument.

Broadening our perspectives on ICU delirium risk factors

ICU delirium is associated with poor patient outcome. Risk factor stratification is essential to the understanding, prevention and treatment of this disorder. Alcohol consumption, smoking and prior cognitive impairment appear strongly correlated with delirium risk. Several potentially modifiable associations deserve prospective study: these include administration of sedatives and opiates; multiple catheters; as well as minimizing physical restraints and enabling visitors.

Dexmedetomidine vs. haloperidol in delirious, agitated, intubated patients: a randomised open-label trial

Introduction

Agitated delirium is common in patients undergoing mechanical ventilation, and is often treated with haloperidol despite concerns about safety and efficacy. Use of conventional sedatives to control agitation can preclude extubation. Dexmedetomidine, a novel sedative and anxiolytic agent, may have particular utility in these patients. We sought to compare the efficacy of haloperidol and dexmedetomidine in facilitating extubation.

Methods

We conducted a randomised, open-label, parallel-groups pilot trial in the medical and surgical intensive care unit of a university hospital. Twenty patients undergoing mechanical ventilation in whom extubation was not possible solely because of agitated delirium were randomised to receive an infusion of either haloperidol 0.5 to 2 mg/hour or dexmedetomidine 0.2 to 0.7 μg/kg/hr, with or without loading doses of 2.5 mg haloperidol or 1 μg/kg dexmedetomidine, according to clinician preference.

Results

Dexmedetomidine significantly shortened median time to extubation from 42.5 (IQR 23.2 to 117.8) to 19.9 (IQR 7.3 to 24) hours (P = 0.016). Dexmedetomidine significantly decreased ICU length of stay, from 6.5 (IQR 4 to 9) to 1.5 (IQR 1 to 3) days (P = 0.004) after study drug commencement. Of patients who required ongoing propofol sedation, the proportion of time propofol was required was halved in those who received dexmedetomidine (79.5% (95% CI 61.8 to 97.2%) vs. 41.2% (95% CI 0 to 88.1%) of the time intubated; P = 0.05). No patients were reintubated; three receiving haloperidol could not be successfully extubated and underwent tracheostomy. One patient prematurely discontinued haloperidol due to QTc interval prolongation.

Conclusions

In this preliminary pilot study, we found dexmedetomidine a promising agent for the treatment of ICU-associated delirious agitation, and we suggest this warrants further testing in a definitive double-blind multi-centre trial.

Trial registration

Clinicaltrials.gov NCT00505804

Rivastigmine for the prevention of postoperative delirium in elderly patients undergoing elective cardiac surgery--a randomized controlled trial

OBJECTIVE

Cardiac surgery is frequently followed by postoperative delirium, which is associated with increased 1-year mortality, late cognitive deficits, and higher costs. Currently, there are no recommendations for pharmacologic prevention of postoperative delirium. Impaired cholinergic transmission is believed to play an important role in the development of delirium. We tested the hypothesis that prophylactic short-term administration of oral rivastigmine, a cholinesterase inhibitor, reduces the incidence of delirium in elderly patients during the first 6 days after elective cardiac surgery.

DESIGN

: Double-blind, randomized, placebo-controlled trial.

SETTING

One Swiss University Hospital.

PATIENTS

One hundred twenty patients aged 65 or older undergoing elective cardiac surgery with cardiopulmonary bypass.

INTERVENTION

Patients were randomly assigned to receive either placebo or 3 doses of 1.5 mg of oral rivastigmine per day starting the evening before surgery and continuing until the evening of the sixth postoperative day.

MEASUREMENTS AND MAIN RESULTS

The primary predefined outcome was delirium diagnosed with the Confusion Assessment Method within 6 days postoperatively. Secondary outcome measures were the results of daily Mini-Mental State Examinations and clock drawing tests, and the use of a rescue treatment consisting of haloperidol and/or lorazepam in patients with delirium. Delirium developed in 17 of 57 (30%) and 18 of 56 (32%) patients in the placebo and rivastigmine groups, respectively (p = 0.8). There was no treatment effect on the time course of Mini-Mental State Examinations and clock drawing tests (p = 0.4 and p = 0.8, respectively). There was no significant difference in the number of patients receiving haloperidol (18 of 57 and 17 of 56, p = 0.9) or lorazepam (38 of 57 and 35 of 56, p = 0.6) in the placebo and rivastigmine groups, respectively.

CONCLUSION

This negative or, because of methodologic issues, possibly failed trial does not support short-term prophylactic administration of oral rivastigmine to prevent postoperative delirium in elderly patients undergoing elective cardiac surgery with cardiopulmonary bypass.

Delirium and sedation in the intensive care unit: survey of behaviors and attitudes of 1384 healthcare professionals

OBJECTIVE

A 2001 survey found that most healthcare professionals considered intensive care unit (ICU) delirium as a serious problem, but only 16% used a validated delirium screening tool. Our objective was to assess beliefs and practices regarding ICU delirium and sedation management.

DESIGN AND SETTING

Between October 2006 and May 2007, a survey was distributed to ICU practitioners in 41 North American hospitals, seven international critical care meetings and courses, and the American Thoracic Society e-mail database.

STUDY PARTICIPANTS

A convenience sample of 1384 healthcare professionals including 970 physicians, 322 nurses, 23 respiratory care practitioners, 26 pharmacists, 18 nurse practitioners and physicians' assistants, and 25 others.

RESULTS

A majority [59% (766 of 1300)] estimated that more than one in four adult mechanically ventilated patients experience delirium. More than half [59% (774 of 1302)] screen for delirium, with 33% of those respondents (258 of 774) using a specific screening tool. A majority of respondents use a sedation protocol, but 29% (396 of 1355) still do not. A majority (76%, 990 of 1309) has a written policy on spontaneous awakening trials (SATs), but the minority of respondents (44%, 446 of 1019) practice spontaneous awakening trials on more than half of ICU days.

CONCLUSIONS

Delirium is considered a serious problem by a majority of healthcare professionals, and the percent of practitioners using a specific screening tool has increased since the last published survey data. Although most respondents have adopted specific sedation protocols and have an approved approach to stopping sedation daily, few report even modest compliance with daily cessation of sedation.

Delirium in the intensive care unit

Delirium is a common manifestation of acute brain dysfunction in critically ill patients with prevalence as high as 75%. In the last years there has been a progressive increase of publications regarding intensive care (ICU) delirium, acknowledging its importance. The occurrence of delirium in ICU is related to more adverse outcomes including self-extubation and removal of catheters, prolonged hospitalization, increased costs, higher mortality, and potentially, long-term cognitive impairment. The pathophysiology explaining the processes subtending the development of delirium is still elusive, though several theories have been discussed. It is known that different risk factors are associated with delirium in the ICU. Patients in ICU frequently receive medications to treat pain and to ensure sedation, but an association between these drugs and delirium has been shown. Therefore, this pharmacological exposure should be modified to reduce the risk factors. Giving the multifactorial genesis of delirium, multicomponent interventions to prevent delirium developed in non-ICU settings can be adapted to critically ill patients with the purpose of reducing the incidence. When delirium is diagnosed the use of typical and atypical antipsychotics may be effective for its treatment. Future studies should evaluate target interventions to prevent delirium in the ICU.

Delirium phenomenology: what can we learn from the symptoms of delirium?

OBJECTIVES

This review focuses on phenomenological studies of delirium, including subsyndromal and prodromal concepts, and their relevance to other elements of clinical profile.

METHODS

A Medline search using the keywords delirium, phenomenology, and symptoms for new data articles published in English between 1998 and 2008 was utilized. The search was supplemented by additional material not identified by Medline but known to the authors.

RESULTS

Understanding of prodromal and subsyndromal concepts is still in its infancy. The characteristic profile can differentiate delirium from other neuropsychiatric disorders. Clinical (motoric) subtyping holds potential but more consistent methods are needed. Studies are almost entirely cross-sectional in design and generally lack comprehensive symptom assessment. Multiple assessment tools are available but are oriented towards hyperactive features and few have demonstrated ability to distinguish delirium from dementia. There is insufficient evidence linking specific phenomenology with etiology, pathophysiology, management, course, and outcome.

CONCLUSIONS

Despite the major advancements of the past decade in many aspects of delirium research, further phenomenological work is crucial to targeting studies of causation, pathophysiology, treatment, and prognosis. We identified eight key areas for future studies.

Delirium and use of sedation agents in intensive care

AIM

The aim of the review was to consider the relationship between delirium and aspects of sedative and analgesic drug use in mechanically ventilated intensive care patients. The basis for routine delirium screening and the implications for nurses are discussed along with a brief outline of the treatment of delirium.

BACKGROUND AND CONTEXT

Delirium is common in intensive care patients and like other markers of organ failure is associated with worse outcomes. The risk of developing delirium is dependent on the patients' individual vulnerability and on the burden of precipitating factors they are exposed to. Detection of delirium in intensive care patients is often difficult and requires the regular use of a validated screening tool. Intensive care patients are exposed to multiple delirium risk factors, and sedative and analgesic agents present an important subgroup, which we can attempt to control. Sedative and analgesic drug choice, their mode of administration, monitoring and titration have consequences for delirium development.

METHOD

Literature review.

CONCLUSIONS

Sedative and analgesic drugs have an important role in the prevention and treatment of delirium in intensive care patients. Routine delirium screening should be included as part of sedation monitoring practice. When detected, treatment is focused on the prompt correction of precipitating factors, non-pharmacological interventions and appropriate drug therapy for symptom control.

Understanding international differences in terminology for delirium and other types of acute brain dysfunction in critically ill patients

BACKGROUND

Delirium (acute brain dysfunction) is a potentially life threatening disturbance in brain function that frequently occurs in critically ill patients. While this area of brain dysfunction in critical care is rapidly advancing, striking limitations in use of terminology related to delirium internationally are hindering cross-talk and collaborative research. In the English literature, synonyms of delirium such as the Intensive Care Unit syndrome, acute brain dysfunction, acute brain failure, psychosis, confusion, and encephalopathy are widely used. This often leads to scientific "confusion" regarding published data and methodology within studies, which is further exacerbated by organizational, cultural and language barriers.

OBJECTIVE

We undertook this multinational effort to identify conflicts in terminology and phenomenology of delirium to facilitate communication across medical disciplines and languages.

METHODS

The evaluation of the terminology used for acute brain dysfunction was determined conducting communications with 24 authors from academic communities throughout countries/regions that speak the 13 variants of the Romanic languages included into this manuscript.

RESULTS

In the 13 languages utilizing Romanic characters, included in this report, we identified the following terms used to define major types of acute brain dysfunction: coma, delirium, delirio, delirium tremens, délire, confusion mentale, delir, delier, Durchgangs-Syndrom, acute verwardheid, intensiv-psykose, IVA-psykos, IVA-syndrom, akutt konfusion/forvirring. Interestingly two terms are very consistent: 100 % of the selected languages use the term coma or koma to describe patients unresponsive to verbal and/or physical stimuli, and 100% use delirium tremens to define delirium due to alcohol withdrawal. Conversely, only 54% use the term delirium to indicate the disorder as defined by the DSM-IV as an acute change in mental status, inattention, disorganized thinking and altered level of consciousness.

CONCLUSIONS

Attempts towards standardization in terminology, or at least awareness of differences across languages and specialties, will help cross-talk among clinicians and researchers.

Pediatric illness severity measures predict delirium in a pediatric intensive care unit

CONTEXT

Delirium in children is a serious but understudied neuropsychiatric disorder. So there is little to guide the clinician in terms of identifying those at risk.

OBJECTIVE

To study, in a pediatric intensive care unit (PICU), the predictive power of widely used generic pediatric mortality scoring systems in relation to the occurrence of pediatric delirium (PD).

DESIGN AND METHODS

Four-year prospective observational study, 2002-2005. Predictors used were the Pediatric Index of Mortality (PIM) and Pediatric Risk of Mortality (PRISM II).

SETTING

A tertiary 8-bed PICU in The Netherlands.

PATIENTS

877 critically ill children who were acutely, nonelectively, and consecutively admitted.

MAIN OUTCOME MEASURE

Pediatric delirium.

MAIN RESULTS

Out of 877 children with mean age 4.4 yrs, 40 were diagnosed with PD (Cumulative incidence: 4.5%), 85% of whom (versus 40% with nondelirium) were mechanically ventilated. The area under the curve was 0.74 for PRISM II and 0.71 for the PIM, with optimal cut-off points at the 60th centile (PRISM: sensitivity: 76%; specificity: 62%; PIM: sensitivity: 82%; specificity: 62%). A PRISM II or PIM score above the 60th centile was strongly associated with later PD in terms of relative risk (PRISM II: risk ratio = 4.9; 95% confidence interval: 2.3-10.1; PIM: RR = 6.7; 95% confidence interval: 3.0-15.0). Given the low incidence of PD, values for positive predictive value were lower (PRISM II: 8.3%; PIM: 8.9%, rising to, respectively, 10.1% and 10.6% in mechanically ventilated patients) and values for negative predictive value were higher (PRISM II: 98.3%; PIM: 98.7%).

LIMITATIONS

Given the relatively low incidence of delirium, a low detection rate biased toward the most severe cases cannot be excluded.

CONCLUSIONS

Given the fact that PIM and PRISM II are widely used mortality scoring instruments, prospective associations with PD suggest additional value for ruling in, or out, patients at risk of PD.

Delirium in the intensive care unit

Delirium, an acute and fluctuating disturbance of consciousness and cognition, is a common manifestation of acute brain dysfunction in critically ill patients, occurring in up to 80% of the sickest intensive care unit (ICU) populations. Critically ill patients are subject to numerous risk factors for delirium. Some of these, such as exposure to sedative and analgesic medications, may be modified to reduce risk. Although dysfunction of other organ systems continues to receive more clinical attention, delirium is now recognized to be a significant contributor to morbidity and mortality in the ICU, and it is recommended that all ICU patients be monitored using a validated delirium assessment instrument. Patients with delirium have longer hospital stays and lower 6-month survival than do patients without delirium, and preliminary research suggests that delirium may be associated with cognitive impairment that persists months to years after discharge. Little evidence exists regarding the prevention and treatment of delirium in the ICU, but multicomponent interventions reduce the incidence of delirium in non-ICU studies. Strategies for the prevention and treatment of ICU delirium are the subjects of multiple ongoing investigations.

Mechanisms of neurologic failure in critical illness

Critical illness frequently is associated with neurologic failure that may involve the central and peripheral nervous systems. Central nervous system failure is associated with a spectrum of neurobehavioral changes including delirium, coma, and long-term cognitive dysfunction. Peripheral neurologic failure, or critical illness neuromuscular abnormalities, is suggested by diffuse arreflexic weakness and protracted respiratory insufficiency, and may also persist long after the acute hospitalization. While the burden of neurological disease complicating critical illness is considerable, preventive or therapeutic options are limited. This article provides an overview of research evaluating the relationship between critical illness and neurologic function, with a special emphasis on underlying mechanisms.

Comparison of the confusion assessment method for the intensive care unit (CAM-ICU) with the Intensive Care Delirium Screening Checklist (ICDSC) for delirium in critical care patients gives high agreement rate(s)

OBJECTIVE

In the intensive care unit (ICU) we assessed the agreement between the delirium ratings of two independent delirium assessment methods: (a) the Confusion Assessment method for the ICU (CAM-ICU); and (b) the Intensive Care Delirium Screening Checklist (ICDSC).

DESIGN

Prospective, descriptive cohort study.

SETTING AND PATIENTS

During a 6-month period, 174 patients (mean age 62.4+/-13.0 years) admitted to the ICU after elective surgery or after an emergency were included and assessed with both delirium assessment systems by two trained independent investigators (research person and bedside nurses) during their ICU stay or for up to 7 days after ICU admission.

INTERVENTIONS

Patients' clinical characteristics at ICU admission day were documented.

MEASUREMENTS AND RESULTS

After excluding permanently unconscious patients with <or=-4 on the Richmond Agitation Sedations scale, delirium was identified in 71 of the 174 patients (41%). The patients who were included were tested in 374 paired but researcher-independent ratings of delirium by both scoring methods. The kappa coefficient determined over 7 days of ICU stay was 0.80 (CI 95%: 0.78-0.84; p<0.001), indicating good agreement.

CONCLUSION

It is concluded from the present investigation that the two scoring methods represent good diagnostic tools with high agreement rates in critical ill ICU patients.