Intensive Care Unit Delirium: A Review of Diagnosis, Prevention, and Treatment

Interventions for preventing intensive care unit delirium in adults

BACKGROUND

Delirium is defined as a disturbance in attention, awareness and cognition with reduced ability to direct, focus, sustain and shift attention, and reduced orientation to the environment. Critically ill patients in the intensive care unit (ICU) frequently develop ICU delirium. It can profoundly affect both them and their families because it is associated with increased mortality, longer duration of mechanical ventilation, longer hospital and ICU stay and long-term cognitive impairment. It also results in increased costs for society.

OBJECTIVES

To assess existing evidence for the effect of preventive interventions on ICU delirium, in-hospital mortality, the number of delirium- and coma-free days, ventilator-free days, length of stay in the ICU and cognitive impairment.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, BIOSIS, International Web of Science, Latin American Caribbean Health Sciences Literature, CINAHL from 1980 to 11 April 2018 without any language limits. We adapted the MEDLINE search for searching the other databases. Furthermore, we checked references, searched citations and contacted study authors to identify additional studies. We also checked the following trial registries: Current Controlled Trials; ClinicalTrials.gov; and CenterWatch.com (all on 24 April 2018).

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of adult medical or surgical ICU patients receiving any intervention for preventing ICU delirium. The control could be standard ICU care, placebo or both. We assessed the quality of evidence with GRADE.

DATA COLLECTION AND ANALYSIS

We checked titles and abstracts to exclude obviously irrelevant studies and obtained full reports on potentially relevant ones. Two review authors independently extracted data. If possible we conducted meta-analyses, otherwise we synthesized data narratively.

MAIN RESULTS

The electronic search yielded 8746 records. We included 12 RCTs (3885 participants) comparing usual care with the following interventions: commonly used drugs (four studies); sedation regimens (four studies); physical therapy or cognitive therapy, or both (one study); environmental interventions (two studies); and preventive nursing care (one study). We found 15 ongoing studies and five studies awaiting classification. The participants were 48 to 70 years old; 48% to 74% were male; the mean acute physiology and chronic health evaluation (APACHE II) score was 14 to 28 (range 0 to 71; higher scores correspond to more severe disease and a higher risk of death). With the exception of one study, all participants were mechanically ventilated in medical or surgical ICUs or mixed. The studies were overall at low risk of bias. Six studies were at high risk of detection bias due to lack of blinding of outcome assessors. We report results for the two most commonly explored approaches to delirium prevention: pharmacologic and a non-pharmacologic intervention.Haloperidol versus placebo (two RCTs, 1580 participants)The event rate of ICU delirium was measured in one study including 1439 participants. No difference was identified between groups, (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.87 to 1.17) (moderate-quality evidence). Haloperidol versus placebo neither reduced or increased in-hospital mortality, (RR 0.98, 95% CI 0.80 to 1.22; 2 studies; 1580 participants (moderate-quality evidence)); the number of delirium- and coma-free days, (mean difference (MD) -0.60, 95% CI -1.37 to 0.17; 2 studies, 1580 participants (moderate-quality of evidence)); number of ventilator-free days (mean 23.8 (MD -0.30, 95% CI -0.93 to 0.33) 1 study; 1439 participants, (high-quality evidence)); length of ICU stay, (MD 0.18, 95% CI -0.60 to 0.97); 2 studies, 1580 participants; high-quality evidence). None of the studies measured cognitive impairment. In one study there were three serious adverse events in the intervention group and five in the placebo group; in the other there were five serious adverse events and three patients died, one in each group. None of the serious adverse events were judged to be related to interventions received (moderate-quality evidence).Physical and cognitive therapy interventions (one study, 65 participants)The study did not measure the event rate of ICU delirium. A physical and cognitive therapy intervention versus standard care neither reduced nor increased in-hospital mortality, (RR 0.94, 95% CI 0.40 to 2.20, I² = 0; 1 study, 65 participants; very low-quality evidence); the number of delirium- and coma-free days, (MD -2.8, 95% CI -10.1 to 4.6, I² = 0; 1 study, 65 participants; very low-quality evidence); the number of ventilator-free days (within the first 28/30 days) was median 27.4 (IQR 0 to 29.2) and 25 (IQR 0 to 28.9); 1 study, 65 participants; very low-quality evidence, length of ICU stay, (MD 1.23, 95% CI -0.68 to 3.14, I² = 0; 1 study, 65 participants; very low-quality evidence); cognitive impairment measured by the MMSE: Mini-Mental State Examination with higher scores indicating better function, (MD 0.97, 95% CI -0.19 to 2.13, I² = 0; 1 study, 30 participants; very low-quality evidence); or measured by the Dysexecutive questionnaire (DEX) with lower scores indicating better function (MD -8.76, 95% CI -19.06 to 1.54, I² = 0; 1 study, 30 participants; very low-quality evidence). One patient experienced acute back pain accompanied by hypotensive urgency during physical therapy.

AUTHORS' CONCLUSIONS

There is probably little or no difference between haloperidol and placebo for preventing ICU delirium but further studies are needed to increase our confidence in the findings. There is insufficient evidence to determine the effects of physical and cognitive intervention on delirium. The effects of other pharmacological interventions, sedation, environmental, and preventive nursing interventions are unclear and warrant further investigation in large multicentre studies. Five studies are awaiting classification and we identified 15 ongoing studies, evaluating pharmacological interventions, sedation regimens, physical and occupational therapy combined or separately, and environmental interventions, that may alter the conclusions of the review in future.

Cholinesterase inhibitors for the treatment of delirium in non-ICU settings

BACKGROUND

Delirium is a common clinical syndrome defined as alterations in attention with an additional disturbance in cognition or perception, which develop over a short period of time and tend to fluctuate during the course of the episode. Delirium is commonly treated in hospitals or community settings and is often associated with multiple adverse outcomes such as increased cost, morbidity, and even mortality. The first-line intervention involves a multicomponent non-pharmacological approach that includes ensuring effective communication and reorientation in addition to providing reassurance or a suitable care environment. There are currently no drugs approved specifically for the treatment of delirium. Clinically, however, various medications are employed to provide symptomatic relief, such as antipsychotic medications and cholinesterase inhibitors, among others.

OBJECTIVES

To evaluate the effectiveness and safety of cholinesterase inhibitors for treating people with established delirium in a non-intensive care unit (ICU) setting.

SEARCH METHODS

We searched ALOIS, which is the Cochrane Dementia and Cognitive Improvement Group's Specialised Register, on 26 October 2017. We also cross-checked the reference lists of included studies to identify any potentially eligible trials.

SELECTION CRITERIA

We included randomised controlled trials, published or unpublished, reported in English or Chinese, which compared cholinesterase inhibitors to placebo or other drugs intended to treat people with established delirium in a non-ICU setting.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. The primary outcomes were duration of delirium, severity of delirium, and adverse events. The secondary outcomes were use of rescue medications, persistent cognitive impairment, length of hospitalisation, institutionalisation, mortality, cost of intervention, leaving the study early, and quality of life. For dichotomous outcomes, we calculated the risk ratio (RR) with 95% confidence intervals (CIs); for continuous outcomes we calculated the mean difference (MD) with 95% CIs. We assessed the quality of evidence using GRADE to generate a 'Summary of findings' table.

MAIN RESULTS

We included one study involving 15 participants from the UK. The included participants were diagnosed with delirium based on the Confusion Assessment Method (CAM) criteria. Eight males and seven females were included, with a mean age of 82.5 years. Seven of the 15 participants had comorbid dementia at baseline. The risk of bias was low in all domains.The study compared rivastigmine with placebo. We did not find any clear differences between the two groups in terms of duration of delirium (MD -3.6, 95% CI -15.6 to 8.4), adverse events (nausea, RR 0.30, 95% CI 0.01 to 6.29), use of rescue medications (RR 0.13, 95% CI 0.01 to 2.1), mortality (RR 0.10, 95% CI 0.01 to 1.56), and leaving the study early (RR 0.88, 95% CI 0.07 to 11.54). Evidence was not available regarding the severity of delirium, persistent cognitive impairment, length of hospitalisation, cost of intervention, or other predefined secondary outcomes.The quality of evidence is low due to the very small sample size.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the use of cholinesterase inhibitors for the treatment of delirium in non-ICU settings. No clear benefits or harms associated with cholinesterase inhibitors were observed when compared with placebo due to the lack of data. More trials are required.

Perioperative myocardial injury and the contribution of hypotension

Mortality in the month following surgery is about 1000 times greater than anesthesia-related intraoperative mortality, and myocardial injury appears to be the leading cause. There is currently no known safe prophylaxis for postoperative myocardial injury, but there are strong associations among hypotension and myocardial injury, renal injury, and death. During surgery, the harm threshold is a mean arterial pressure of about 65 mmHg. In critical care units, the threshold appears to be considerably greater, perhaps 90 mmHg. The threshold triggering injury on surgical wards remains unclear but may be in between. Much of the association between hypotension and serious complications surely results from residual confounding, but sparse randomized data suggest that at least some harm can be prevented by intervening to limit hypotension. Reducing hypotension may therefore improve perioperative outcomes.

Inattentive Delirium vs. Disorganized Thinking: A New Axis to Subcategorize PACU Delirium

Background: Assessment of patients for delirium in the Post Anesthesia Care Unit (PACU) is confounded by the residual effects of the varied anesthetic and analgesic regimens employed during surgery and by the physiological consequences of surgery such as pain. Nevertheless, delirium diagnosed at this early stage has been associated with adverse clinical outcomes. The last decade has seen the emergence of the confusion assessment method-intensive care unit (CAM-ICU) score as a quick practical method of detecting delirium in clinical situations. Nonetheless, this tool has not been specifically designed for use in this immediate postoperative setting. Methods: Patients enrolled in a larger observational study were administered the CAM-ICU delirium screening tool 15 min after the latter of return of responsiveness to command or arrival in the post-anesthesia care unit. Numerical pain rating scores were also recorded. In addition, we reviewed additional behavioral observations suggestive of disordered thinking, such as hallucinations, a non-reactive eyes-open state, or an inability to state a pain score. Results: Two-hundred and twenty-nine patients underwent CAM-ICU testing in PACU. 33 patients (14%) were diagnosed with delirium according to CAM-ICU criteria; 25 of these were inattentive with low arousal, seven were inattentive with high arousal, and one was inattentive and calm and with disordered thinking. Using our extended criteria an additional eleven patients showed signs of disordered thinking. CAM-ICU delirium was associated with increased length of operation (p = 0.028), but a positive CAM-PACU designation was associated with both increased operation length and age (p = 0.003 and 0.010 respectively). Two of the CAM-ICU positive patients with inattention and high arousal reported high pain scores and were not classified as CAM-PACU positive. Conclusion: Disordered thinking is correlated with older patients and longer operations. The sensitivity of the existing CAM-ICU score in diagnosing delirium or disordered thinking in PACU patients is improved by the inclusion of a few extra criteria, namely: patients having perceptual hallucinations, in an unreactive eyes-open state, or who cannot state a pain score. We present this alternative screening tool for use in the post-anesthetic period, which we have named CAM-PACU.

Systematic review of prediction models for delirium in the older adult inpatient

OBJECTIVE

To identify existing prognostic delirium prediction models and evaluate their validity and statistical methodology in the older adult (≥60 years) acute hospital population.

DESIGN

Systematic review.

DATA SOURCES AND METHODS

PubMed, CINAHL, PsychINFO, SocINFO, Cochrane, Web of Science and Embase were searched from 1 January 1990 to 31 December 2016. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses and CHARMS Statement guided protocol development.

INCLUSION CRITERIA

age >60 years, inpatient, developed/validated a prognostic delirium prediction model.

EXCLUSION CRITERIA

alcohol-related delirium, sample size ≤50. The primary performance measures were calibration and discrimination statistics. Two authors independently conducted search and extracted data. The synthesis of data was done by the first author. Disagreement was resolved by the mentoring author.

RESULTS

The initial search resulted in 7,502 studies. Following full-text review of 192 studies, 33 were excluded based on age criteria (<60 years) and 27 met the defined criteria. Twenty-three delirium prediction models were identified, 14 were externally validated and 3 were internally validated. The following populations were represented: 11 medical, 3 medical/surgical and 13 surgical. The assessment of delirium was often non-systematic, resulting in varied incidence. Fourteen models were externally validated with an area under the receiver operating curve range from 0.52 to 0.94. Limitations in design, data collection methods and model metric reporting statistics were identified.

CONCLUSIONS

Delirium prediction models for older adults show variable and typically inadequate predictive capabilities. Our review highlights the need for development of robust models to predict delirium in older inpatients. We provide recommendations for the development of such models.

Effect of organisational factors on the variation in incidence of delirium in intensive care unit patients: A systematic review and meta-regression analysis

BACKGROUND

Delirium occurs frequently in intensive care unit (ICU) patients and is associated with numerous deleterious outcomes. There is a large variation in reported delirium occurrence rates, ranging from 4% to 89%. Apart from patient and treatment-related factors, organisational factors could influence delirium incidence, but this is currently unknown.

OBJECTIVE

To systematically review delirium incidence and determine whether or not organisational factors may contribute to the observed delirium incidence in adult ICU patients.

METHODS

Systematic review of prospective cohort studies reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Included articles were independently assessed by two researchers. Quality of the articles was determined using the Strengthening the Reporting of Observational Studies in Epidemiology checklist. Subsequently, apart from patient characteristics, a meta-regression analysis was performed on available organisational factors, including hospital type, screening method and screening frequency.

DATA SOURCES

PubMed, Embase, CINAHL, and Cochrane Library databases were searched from inception to 27 January 2017, without language limitation.

RESULTS

A total of 9357 articles were found, of which 19 articles met the inclusion criteria and were considered as true delirium incidence studies. The articles were of good methodological quality (median [interquartile range] 32/38 [30-35] points), published between 2005 and 2016, originated from 17 countries. A total of 9867 ICU patients were included. The incidence rate of delirium varied between 4% and 55%, with a mean ± standard deviation of 29 ± 14%. Data relating to three organisational factors were included in the studies, but they were not significantly associated with the reported delirium incidence: hospital type (p 0.48), assessment methods (p 0.41), and screening frequency (p 0.28).

CONCLUSIONS

The mean incidence of delirium in the ICU was 29%. The organisational factors found including methods of delirium assessment, screening frequency, and hospital type were not related to the reported ICU delirium incidence.

Delirium in Older Persons: Advances in Diagnosis and Treatment

Importance

Delirium is defined as an acute disorder of attention and cognition. It is a common, serious, and often fatal condition among older patients. Although often underrecognized, delirium has serious adverse effects on the individual's function and quality of life, as well as broad societal effects with substantial health care costs.

Objective

To summarize the current state of the art in diagnosis and treatment of delirium and to highlight critical areas for future research to advance the field.

Evidence Review

Search of Ovid MEDLINE, Embase, and the Cochrane Library for the past 6 years, from January 1, 2011, until March 16, 2017, using a combination of controlled vocabulary and keyword terms. Since delirium is more prevalent in older adults, the focus was on studies in elderly populations; studies based solely in the intensive care unit (ICU) and non-English-language articles were excluded.

Findings

Of 127 articles included, 25 were clinical trials, 42 cohort studies, 5 systematic reviews and meta-analyses, and 55 were other categories. A total of 11 616 patients were represented in the treatment studies. Advances in diagnosis have included the development of brief screening tools with high sensitivity and specificity, such as the 3-Minute Diagnostic Assessment; 4 A's Test; and proxy-based measures such as the Family Confusion Assessment Method. Measures of severity, such as the Confusion Assessment Method-Severity Score, can aid in monitoring response to treatment, risk stratification, and assessing prognosis. Nonpharmacologic approaches focused on risk factors such as immobility, functional decline, visual or hearing impairment, dehydration, and sleep deprivation are effective for delirium prevention and also are recommended for delirium treatment. Current recommendations for pharmacologic treatment of delirium, based on recent reviews of the evidence, recommend reserving use of antipsychotics and other sedating medications for treatment of severe agitation that poses risk to patient or staff safety or threatens interruption of essential medical therapies.

Conclusions and Relevance

Advances in diagnosis can improve recognition and risk stratification of delirium. Prevention of delirium using nonpharmacologic approaches is documented to be effective, while pharmacologic prevention and treatment of delirium remains controversial.

[Elderly patients and intensive care: Systematic review and geriatrician's point of view]

The global population is aging and intensive care unit admission rate of elderly patients is dramatically increasing. The objective of this review is to provide an overview of the literature about the management of elderly patients in intensive care unit and more specifically about epidemiology, admission criteria, mortality, functional prognosis and ethical aspects. We also discuss the data on cardiorespiratory arrest, shock, acute respiratory failure and delirium. The mortality rate of patients over 80 years old in intensive care unit can reach up to 70% at 1year, but is dependent on many factors, such as comorbidities or frailty. Above all, more than half of elderly patients recover their long-term autonomy. Their quality of life is comparable to that of the same age population. Considering that the first 3months after an intensive care unit stay are the most decisive in terms of vital and functional prognosis, we will discuss strategies to improve care through the creation of dedicated intensive care-geriatrics networks.