Delirium after cardiac surgery: a critical review

Diagnostic accuracy of the "4 A's Test" delirium screening tool for the postoperative cardiac surgery ward

BACKGROUND

Delirium is prevalent and underdetected among cardiac surgery patients on the postoperative ward. This study aimed to validate the 4 A's Test delirium screening tool and evaluate its accuracy both when used by research assistants and when subsequently implemented by nursing staff on the ward.

METHODS

This single-center, prospective observational study evaluated the performance of the 4 A's Test administered by research assistants (phase 1) and nursing staff (phase 2). Assessments were undertaken during the patients' first 3 postoperative days on the postcardiac surgery ward along with previous routine nurse-led Confusion Assessment Method assessments. These index tests were compared with a reference standard diagnosis of delirium based on Diagnostic and Statistical Manual of Mental Disorders 5th Edition criteria. Surveys regarding delirium screening were administered to nurses pre- and postimplementation of the 4 A's Test in phase 2 of the study.

RESULTS

In phase 1, a total of 137 patients were enrolled, of whom 24.8% experienced delirium on the postoperative cardiac ward. The 4 A's Test had a sensitivity of 85% (95% confidence interval, 73-93) and a specificity of 90% (95% confidence interval, 85-93) compared with the reference standard. The nurse-assessed Confusion Assessment Method had a sensitivity of 23% (95% confidence interval, 13-37) and specificity of 100% (95% confidence interval, 99-100). In phase 2, nurses (n = 51) screened 179 patients for delirium using the 4 A's Test. Compared with the reference rater, the 4 A's Test had a sensitivity of 58% (95% confidence interval, 28-85) and specificity of 94% (95% confidence interval, 85-98). Postimplementation, 64% of nurses thought that the 4 A's Test improved their confidence in delirium detection, and 76% of nurses would consider routine 4 A's Test use.

CONCLUSIONS

The 4 A's Test demonstrated moderate sensitivity and high specificity to detect delirium in a real-world setting after cardiac surgery on the postoperative ward. A modified model of use with less frequent administration, along with increased engagement of the postoperative team, is recommended to improve early delirium detection on the cardiac surgery postoperative ward.

Incidence of delirium after cardiac surgery: protocol for the DELIRIUM-CS Canada cross-sectional cohort study

BACKGROUND

Delirium is a recognized complication of cardiac surgery and is the focus of increasing attention owing to its negative effect on postoperative outcomes. However, little is known about the actual incidence of delirium following cardiac surgery, with published rates ranging widely, from 3%-78%. We describe the protocol for the DELIRIUM-CS Canada study, which will use validated and easily implementable bedside tools to determine the incidence of postoperative delirium in a contemporary cardiac surgery population. We hypothesize that delirium, identified through a systematic and standardized screening protocol, is a highly prevalent, though variable, condition following cardiac surgery.

METHODS

The DELIRIUM-CS Canada study is a multicentre cross-sectional cohort study. Over a 3-month period, all patients undergoing major cardiac surgical procedures at 10 participating centres will be screened for postoperative delirium by means of the Intensive Care Delirium Screening Checklist or the Confusion Assessment Method for the Intensive Care Unit. Delirium screening will be conducted for 7 days following the date of surgery or until the initial discharge from the intensive care unit. In addition to reporting an overall rate of delirium, we will report unadjusted and adjusted incidence rates of delirium by institution and for the entire cohort. Risk adjustment will be performed with the use of multivariate regression modelling techniques.

INTERPRETATION

The results of this study will provide valuable insight into the true burden of delirium among patients having undergone a major cardiac surgical procedure in the current era. This is the first step in creating a multifaceted delirium prevention/treatment clinical pathway for patients undergoing cardiac surgery. Trial registration: ClinicalTrials.gov, no. NCT02206880.

Detection, Prevention, and Management of Delirium in the Critically Ill Cardiac Patient and Patients Who Undergo Cardiac Procedures

Delirium is an acute change in cognitive functioning, characterized by inattention and associated with alterations in awareness and fluctuation in arousal, disorganized thinking, or altered level that preferentially affects older adult patients. In the acutely ill cardiac patient, the incidence of delirium has been reported as high as 73%, depending on the type and sensitivity of delirium assessment. Cardiac patients with delirium experience higher rates of in-hospital and longer-term mortality and are at risk for progressive cognitive impairment, loss of functional independence, and increased hospitalization costs. As such, delirium represents an undesirable outcome in cardiac patients. Care improvements such as identifying risk of delirium at time of admission or in the preoperative setting; training cardiologist, surgeons, anaesthesiologists and nurses to screen for delirium; implementing delirium prevention programs; and developing standardized delirium treatment protocols might reduce the incidence of delirium and its associated morbidity.

Current approach to diagnosis and treatment of delirium after cardiac surgery

Delirium after cardiac surgery remains a common occurrence that results in significant short- and long-term morbidity and mortality. It continues to be underdiagnosed given its complex presentation and multifactorial etiology; however, its prevalence is increasing given the aging cardiac surgical population. This review highlights the perioperative risk factors, tools to assist in diagnosing delirium, and current pharmacological and nonpharmacological therapy options.

Postoperative Delirium in the Geriatric Patient

Postoperative delirium, a common complication in older surgical patients, is independently associated with increased morbidity and mortality. Patients older than 65 years receive greater than one-third of the more than 40 million anesthetics delivered yearly in the United States. This number is expected to increase with the aging of the population. Thus, it is increasingly important that perioperative clinicians who care for geriatric patients have an understanding of the complex syndrome of postoperative delirium.

Preoperative assessment of the older surgical patient: honing in on geriatric syndromes

Nearly 50% of Americans will have an operation after the age of 65 years. Traditional preoperative anesthesia consultations capture only some of the information needed to identify older patients (defined as ≥65 years of age) undergoing elective surgery who are at increased risk for postoperative complications, prolonged hospital stays, and delayed or hampered functional recovery. As a catalyst to this review, we compared traditional risk scores (eg, cardiac-focused) to geriatric-specific risk measures from two older female patients seen in our preoperative clinic who were scheduled for elective, robotic-assisted hysterectomies. Despite having a lower cardiac risk index and Charlson comorbidity score, the younger of the two patients presented with more subtle negative geriatric-specific risk predictors – including intermediate or pre-frail status, borderline malnutrition, and reduced functional/mobility – which may have contributed to her 1-day-longer length of stay and need for readmission. Adequate screening of physiologic and cognitive reserves in older patients scheduled for surgery could identify at-risk, vulnerable elders and enable proactive perioperative management strategies (eg, strength, balance, and mobility prehabilitation) to reduce adverse postoperative outcomes and readmissions. Here, we describe our initial two cases and review the stress response to surgery and the impact of advanced age on this response as well as preoperative geriatric assessments, including frailty, nutrition, physical function, cognition, and mood state tests that may better predict postoperative outcomes in older adults. A brief overview of the literature on anesthetic techniques that may influence geriatric-related syndromes is also presented.

Postoperative delirium following transcatheter aortic valve implantation: a historical cohort study

PURPOSE

Transcatheter aortic valve implantation (TAVI) techniques show favourable survival outcomes in high-risk patients, but the incidence of postoperative delirium is unknown. We conducted a historical cohort study to compare postoperative delirium in retrograde transfemoral (TF) versus anterograde transapical (TA) TAVI procedures. We also sought to identify independent predictors of delirium following TAVI.

METHODS

We performed a retrospective chart review on all patients who underwent TF (n = 77) or TA (n = 45) TAVI during 2008 and 2009 at St. Paul's Hospital (Vancouver, BC, Canada), the pioneering centre for these procedures. The primary outcome was a documented physician diagnosis of delirium. Abstracted data included information on demographics, medical history, surgical procedure, anesthesia, and postoperative care. We employed a multivariable logistic regression to identify independent predictors of delirium.

RESULTS

Delirium occurred in 12% of TF patients vs 53% of TA patients (P < 0.001). Preoperatively, the groups differed significantly in the rates of hypertension, pulmonary hypertension, dyslipidemia, peripheral vascular disease, congestive heart failure, previous myocardial infarction, and memory impairment. Differences in anesthetic management were also observed between the TF vs TA groups regarding inhalational anesthetics, opioids, neuromuscular blockers, antihemorrhagic drugs, and antibiotics. Independent predictors for delirium after TAVI included coronary artery disease (odds ratio [OR] 12.7; 95% confidence interval [CI] 1.0 to 154.9), cognitive impairment (OR 6.5; 95% CI 1.8 to 23.2), and cardiac arrhythmia (OR 3.5; 95% CI 1.1 to 11.6). Compared to the TF approach, TA-TAVI independently increased the risk of delirium (OR 13.8; 95% CI 3.3 to 59.0).

CONCLUSIONS

Patients undergoing TA-TAVI had a markedly increased incidence of postoperative delirium compared with patients undergoing TF-TAVI.

Outcomes of a Geriatric Liaison Intervention to Prevent the Development of Postoperative Delirium in Frail Elderly Cancer Patients: Report on a Multicentre, Randomized, Controlled Trial

Background

Delirium is a serious and common postoperative complication, especially in frail elderly patients. The aim of this study was to evaluate the effect of a geriatric liaison intervention in comparison with standard care on the incidence of postoperative delirium in frail elderly cancer patients treated with an elective surgical procedure for a solid tumour.

Methods

Patients over 65 years of age who were undergoing elective surgery for a solid tumour were recruited to a multicentre, prospective, randomized, controlled trial. The patients were randomized to standard treatment versus a geriatric liaison intervention. The intervention consisted of a preoperative geriatric consultation, an individual treatment plan targeted at risk factors for delirium, daily visits by a geriatric nurse during the hospital stay and advice on managing any problems encountered. The primary outcome was the incidence of postoperative delirium. The secondary outcome measures were the severity of delirium, length of hospital stay, complications, mortality, care dependency, quality of life, return to an independent preoperative living situation and additional care at home.

Results

In total, the data of 260 patients were analysed. Delirium occurred in 31 patients (11.9%), and there was no significant difference between the incidence of delirium in the intervention group and the usual-care group (9.4% vs. 14.3%, OR: 0.63, 95% CI: 0.29–1.35).

Conclusions

Within this study, a geriatric liaison intervention based on frailty for the prevention of postoperative delirium in frail elderly cancer patients undergoing elective surgery for a solid tumour has not proven to be effective.

Trial Registration

Nederlands Trial Register Trial ID NTR 823

Cortisol levels and neuropsychiatric diagnosis as markers of postoperative delirium: a prospective cohort study

Introduction

The pathophysiology of delirium after cardiac surgery is largely unknown. The purpose of this study was to investigate whether increased concentration of preoperative and postoperative plasma cortisol predicts the development of delirium after coronary artery bypass graft surgery. A second aim was to assess whether the association between cortisol and delirium is stress related or mediated by other pathologies, such as major depressive disorder (MDD) or cognitive impairment.

Methods

The patients were examined 1 day preoperatively with the Mini International Neuropsychiatric Interview and the Montreal Cognitive Assessment and the Trail Making Test to screen for depression and for cognitive impairment, respectively. Blood samples for cortisol levels were collected both preoperatively and postoperatively. The Confusion Assessment Method for the Intensive Care Unit was used within the first 5 days postoperatively to screen for a diagnosis of delirium.

Results

Postoperative delirium developed in 36% (41 of 113) of participants. Multivariate logistic regression analysis revealed two groups independently associated with an increased risk of developing delirium: those with preoperatively raised cortisol levels; and those with a preoperative diagnosis of MDD associated with raised levels of cortisol postoperatively. According to receiver operating characteristic analysis, the most optimal cutoff values of the preoperative and postoperative cortisol concentration that predict the development of delirium were 353.55 nmol/l and 994.10 nmol/l, respectively.

Conclusion

Raised perioperative plasma cortisol concentrations are associated with delirium after coronary artery bypass graft surgery. This may be an important pathophysiological consideration in the increased risk of postoperative delirium seen in patients with a preoperative diagnosis of MDD.

Incidence and predictive factors of delirium in hospitalised neurological patients

INTRODUCTION

Delirium is a condition with a high prevalence in hospitalised patients (10%-30%), and it has important prognostic implications. There are few prospective studies of the incidence of delirium in Spain, and most of these were carried out in surgical wards or intensive care units. Our objective is to calculate the incidence of delirium in a neurological department and describe characteristics of affected patients.

METHODS

Longitudinal descriptive study including all patients admitted to the neurology department in an 8-week period. The CAM score for diagnosing delirium was recorded on the first, second and fifth day of hospitalisation and we recorded demographic data, medical history, analytical data (including inflammatory markers), use of anticholinergic treatments, cognitive and functional state at admission, reason for admission, length of stay, and other events during hospitalisation.

RESULTS

We studied 115 patients and found an incidence of delirium of 16.52%. There was a significant correlation between delirium and age, cognitive state at admission according to the Pfeiffer test, functional situation at admission according to the Canadian Neurological Scale, kidney failure, history of stroke, anticholinergic treatment, erythrocyte sedimentation rate, and C-reactive protein. These patients were also hospitalised for longer periods of time.

CONCLUSIONS

These results confirm a high incidence of delirium in our geographical area. Although additional studies with larger samples are needed, we would like to emphasise the importance of several risk factors which may enable early detection of patients who are at risk for developing delirium during hospitalisation. This would permit preventive action and early treatment for these patients.

Delirium in hospitalized patients: implications of current evidence on clinical practice and future avenues for research--a systematic evidence review

BACKGROUND

Despite the significant burden of delirium among hospitalized adults, critical appraisal of systematic data on delirium diagnosis, pathophysiology, treatment, prevention, and outcomes is lacking.

PURPOSE

To provide evidence-based recommendations for delirium care to practitioners, and identify gaps in delirium research.

DATA SOURCES

Medline, PubMed, the Cochrane Library, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) information systems from January 1966 to April 2011.

STUDY SELECTION

All published systematic evidence reviews (SERs) on delirium were evaluated.

DATA EXTRACTION

Three reviewers independently extracted the data regarding delirium risk factors, diagnosis, prevention, treatment, and outcomes, and critically appraised each SER as good, fair, or poor using the United States Preventive Services Task Force criteria.

DATA SYNTHESIS

Twenty-two SERs graded as good or fair provided the data. Age, cognitive impairment, depression, anticholinergic drugs, and lorazepam use were associated with an increased risk for developing delirium. The Confusion Assessment Method (CAM) is reliable for delirium diagnosis outside of the intensive care unit. Multicomponent nonpharmacological interventions are effective in reducing delirium incidence in elderly medical patients. Low-dose haloperidol has similar efficacy as atypical antipsychotics for treating delirium. Delirium is associated with poor outcomes independent of age, severity of illness, or dementia.

CONCLUSION

Delirium is an acute, preventable medical condition with short- and long-term negative effects on a patient's cognitive and functional states.

Incidence and short-term consequences of delirium in critically ill patients: A prospective observational cohort study

BACKGROUND

Delirium is a serious and frequent psycho-organic disorder in critically ill patients. Reported incidence rates vary to a large extent and there is a paucity of data concerning delirium incidence rates for the different subgroups of intensive care unit (ICU) patients and their short-term health consequences.

OBJECTIVES

To determine the overall incidence and duration of delirium, per delirium subtype and per ICU admission diagnosis. Furthermore, we determined the short-term consequences of delirium.

DESIGN

Prospective observational study.

PARTICIPANTS AND SETTING

All adult consecutive patients admitted in one year to the ICU of a university medical centre.

METHODS

Delirium was assessed using the Confusion Assessment Method-ICU three times a day. Delirium was divided in three subtypes: hyperactive, hypoactive and mixed subtype. As measures for short-term consequences we registered duration of mechanical ventilation, re-intubations, incidence of unplanned removal of tubes, length of (ICU) stay and in-hospital mortality.

RESULTS

1613 patients were included of which 411 (26%) developed delirium. The incidence rate in the neurosurgical (10%) and cardiac surgery group (12%) was the lowest, incidence was intermediate in medical patients (40%), while patients with a neurological diagnosis had the highest incidence (64%). The mixed subtype occurred the most (53%), while the hyperactive subtype the least (10%). The median delirium duration was two days [IQR 1-7], but significantly longer (P<0.0001) for the mixed subtype. More delirious patients were mechanically ventilated and for a longer period of time, were more likely to remove their tube and catheters, stayed in the ICU and hospital for a longer time, and had a six times higher chance of dying compared to non-delirium ICU patients, even after adjusting for their severity of illness score. Delirium was associated with an extended duration of mechanical ventilation, length of stay in the ICU and in-hospital, as well as with in-hospital mortality.

CONCLUSIONS

The delirium incidence in a mixed ICU population is high and differs importantly between ICU admission diagnoses and the subtypes of delirium. Patients with delirium had a significantly higher incidence of short-term health problems, independent from their severity of illness and this was most pronounced in the mixed subtype of delirium. Delirium is significantly associated with worse short-term outcome.

A clinical update on delirium: from early recognition to effective management

Delirium is a neuropsychiatric syndrome characterized by altered consciousness and attention with cognitive, emotional and behavioural symptoms. It is particularly frequent in elderly people with medical or surgical conditions and is associated with adverse outcomes. Predisposing factors render the subject more vulnerable to a congregation of precipitating factors which potentially affect brain function and induce an imbalance in all the major neurotransmitter systems. Early diagnosis of delirium is crucial to improve the prognosis of patients requiring the identification of subtle and fluctuating signs. Increased awareness of clinical staff, particularly nurses, and routine screening of cognitive function with standardized instruments, can be decisive to increase detection rates of delirium. General measures to prevent delirium include the implementation of protocols to systematically identify and minimize all risk factors present in a particular clinical setting. As soon as delirium is recognized, prompt removal of precipitating factors is warranted together with environmental changes and early mobilization of patients. Low doses of haloperidol or olanzapine can be used for brief periods, for the behavioural control of delirium. All of these measures are a part of the multicomponent strategy for prevention and treatment of delirium, in which the nursing care plays a vital role.

Structured analyses of interventions to prevent delirium

BACKGROUND

Delirium is one of the most serious complications in hospitalized elderly, with incidences ranging from 3-56%. The objective of this meta-analysis was two-fold, first to investigate if interventions to prevent delirium are effective and second to explore which factors increase the effectiveness of these interventions.

METHODS

An electronic search was carried out on articles published between January 1979 and July 2009. Abstracts were reviewed, data were extracted and methodologic quality was assessed by two independent reviewers. Effect sizes of the interventions were expressed as ORs (odds ratios) and 95%CIs (confidence intervals). A random effect model was used to provide pooled ORs. To explore which factors increase the effectiveness of the interventions, ORs were stratified for several factors.

RESULTS

Sixteen relevant studies were found. Overall the included studies showed a positive result of any intervention to prevent delirium (pooled OR: 0.64; 95%CI: 0.46-0.88). The largest effect was seen in studies on populations with an incidence of delirium above 30% in the control group (pooled OR: 0.34; 95%CI: 0.16-0.71 versus 0.76; 95%CI: 0.60-0.97).

CONCLUSIONS

Interventions to prevent delirium are effective. Interventions seem to be more effective when the incidence of delirium in the population under study is above 30%. To maximize the options for a cost-effective strategy of delirium prevention it might be useful to offer an intervention to a selected population.

Psychiatric aspects of heart and lung disease in critical care

Psychiatric issues are important in the management of patients with heart and lung disease in acute, intensive, and critical care. Adjustment disorders, anxiety disorders, depression, and delirium, sometimes in association with substance abuse and withdrawal problems, are the most common issues, and may affect risk and prognosis of the associated general medical conditions and management in the acute care setting. In children with lung and heart diseases requiring critical care, appreciation of cognitive and social-psychologic developmental milestones is necessary to provide adequate care.

Early postoperative delirium after open-heart cardiac surgery is associated with decreased bispectral EEG and increased cortisol and interleukin-6

PURPOSE

It is difficult to substantiate the clinical diagnosis of postoperative delirium with objective parameters in intensive care units (ICU). The purpose of this study was to analyze (1) whether the bilateral bispectral (BIS) index, (2) cortisol as a stress marker, and (3) interleukin-6 as a marker of inflammation were different in delirious patients as compared to nondelirious ones after cardiac surgery.

METHODS

On the first postoperative day, delirium was analyzed in 114 patients by using the confusion assessment method for ICU (CAM-ICU). Bilateral BIS data were determined; immediately thereafter plasma samples were drawn to analyze patients' blood characteristics. The current ICU medication, hemodynamic characteristics, SOFA and APACHE II scores, and artificial ventilation were noted.

RESULTS

Delirium was detected at 19.1 ± 4.8 h after the end of surgery in 32 of 114 patients (28%). Delirious patients were significantly older than nondelirious ones and were artificially ventilated 4.7-fold more often during the testing. In delirious patients, plasma cortisol and interleukin-6 levels were higher (p = 0.01). The mean BIS index was significantly lower in delirious patients (72.6 (69.6-89.1); median [interquartile range (IQR), 25th-75th percentiles] than in nondelirious patients, 84.8 (76.8-89.9). BIS EEG raw data analysis detected significant lower relative alpha and higher theta power. A significant correlation was found between plasma cortisol levels and BIS index.

CONCLUSIONS

Early postoperative delirium after cardiac surgery was characterized by increased stress levels and inflammatory reaction. BIS index measurements showed lower cortical activity in delirious patients with a low sensitivity (27%) and high specificity (96%).

Incidence and predictors of delirium after cardiac surgery: Results from The IPDACS Study

OBJECTIVE

Delirium after cardiac surgery is a serious complication that results in higher morbidity and mortality rates, and prolongs hospitalisation. However, the knowledge base regarding the issue of postoperative delirium is still limited. Therefore, in the current study, we evaluated the incidence and independent perioperative risk factors of delirium after cardiac surgery.

METHODS

The IPDACS Study recruited 563 consecutive patients undergoing cardiac surgery with cardiopulmonary bypass. The subjects were preoperatively examined by psychiatrists using the Mini-Mental State Examination and the Mini International Neuropsychiatric Interview to assess psychiatric comorbidity. Additionally, other variables connected to the patients' medical condition and surgical and anaesthetic procedures were evaluated. A diagnosis of delirium following surgical intervention was based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria.

RESULTS

The incidence of postoperative delirium according to DSM-IV criteria was 16.3% (95% confidence interval: 13.5-19.6). Multivariate stepwise logistic regression analysis revealed that advanced age, preoperative cognitive impairment, an ongoing episode of major depression, anaemia, atrial fibrillation, prolonged intubation and postoperative hypoxia were independently associated with delirium after cardiac surgery.

CONCLUSION

According to the current analysis, the aforementioned conditions independently predispose to delirium following cardiac surgery. Since some of these factors can be successfully treated and eliminated preoperatively and postoperatively, this study should be helpful in reducing the risk of delirium and in improving the medical care of patients undergoing cardiac surgery (Clinical Trials Identifier: NCT00784576).

Delirium after coronary artery bypass graft surgery and late mortality

OBJECTIVE

Delirium is common after cardiac surgery, although under-recognized, and its long-term consequences are likely underestimated. The primary goal of this study was to determine whether patients with delirium after coronary artery bypass graft (CABG) surgery have higher long-term out-of-hospital mortality when compared with CABG patients without delirium.

METHODS

We studied 5,034 consecutive patients undergoing CABG surgery at a single institution from 1997 to 2007. Presence or absence of neurologic complications, including delirium, was assessed prospectively. Survival analysis was performed to determine the role of delirium in the hazard of death, including a propensity score to adjust for potential confounders. These analyses were repeated to determine the association between postoperative stroke and long-term mortality.

RESULTS

Individuals with delirium had an increased hazard of death (adjusted hazard ratio [HR], 1.65; 95% confidence interval [CI], 1.38-1.97) up to 10 years postoperatively, after adjustment for perioperative and vascular risk factors. Patients with postoperative stroke had a HR of 2.34 (95% CI, 1.87-2.92). The effect of delirium on subsequent mortality was the strongest among those without a prior stroke (HR 1.83 vs HR 1.11 [with a prior stroke] [p-interaction = 0.02]) or who were younger (HR 2.42 [<65 years old] vs HR 1.49 [>/=65 years old] [p-interaction = 0.04]).

INTERPRETATION

Delirium after cardiac surgery is a strong independent predictor of mortality up to 10 years postoperatively, especially in younger individuals and in those without prior stroke. Future studies are needed to determine the impact of delirium prevention and/or treatment in long-term patient mortality.

The neuroinflammatory hypothesis of delirium

Delirium is a neuropsychiatric syndrome characterized by a sudden and global impairment in consciousness, attention and cognition. It is particularly frequent in elderly subjects with medical or surgical conditions and is associated with short- and long-term adverse outcomes. The pathophysiology of delirium remains poorly understood as it involves complex multi-factorial dynamic interactions between a diversity of risk factors. Several conditions associated with delirium are characterized by activation of the inflammatory cascade with acute release of inflammatory mediators into the bloodstream. There is compelling evidence that acute peripheral inflammatory stimulation induces activation of brain parenchymal cells, expression of proinflammatory cytokines and inflammatory mediators in the central nervous system. These neuroinflammatory changes induce neuronal and synaptic dysfunction and subsequent neurobehavioural and cognitive symptoms. Furthermore, ageing and neurodegenerative disorders exaggerate microglial responses following stimulation by systemic immune stimuli such as peripheral inflammation and/or infection. In this review we explore the neuroinflammatory hypothesis of delirium based on recent evidence derived from animal and human studies.

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 in the acute care setting: characteristics, diagnosis and treatment

Delirium is a neurobehavioral syndrome caused by the transient disruption of normal neuronal activity secondary to systemic disturbances. It is also the most common psychiatric syndrome found in the general hospital setting, its prevalence surpassing better known psychiatric disorders. This article reviews the published literature on delirium and addresses the epidemiology, known etiologic factors, presentation and characteristics of delirium, while emphasizing what is known about treatment strategies and prevention. Given increasing evidence that delirium is not always reversible and the many sequelae associated with its development, physicians must do everything possible to prevent its occurrence or shorten its duration, by recognizing its symptoms early, correcting underlying contributing causes, and using treatment strategies proven to help recover functional status.

Psychiatric aspects of heart and lung disease in critical care

Psychiatric issues are important in the management of patients with heart and lung disease in acute, intensive, and critical care. Adjustment disorders, anxiety disorders, depression, and delirium, sometimes in association with substance abuse and withdrawal problems, are the most common issues, and may affect risk and prognosis of the associated general medical conditions and management in the acute care setting. In children with lung and heart diseases requiring critical care, appreciation of cognitive and social-psychologic developmental milestones is necessary to provide adequate care.

Prevalence and Risk Factors for Postoperative Delirium in a Cardiovascular Intensive Care Unit

Background Delirium after cardiac surgery is a common complication in cardiovascular intensive care units. The prevalence of delirium and its likely risk factors have not previously been explored in a single sample of postoperative cardiac patients in an intensive care unit.

Objective To compare a variety of characteristics in patients with and without delirium and to identify risk factors associated with delirium in patients hospitalized in an intensive care unit after cardiac surgery.

Methods A retrospective chart review was used to collect data on 288 patients who had open heart surgery during the period 2004 to 2005 at Chang Gung Memorial Hospital in northern Taiwan. A researcher-designed checklist of 52 patient-related risk factors for delirium was used to collect preoperative, intra-operative, and postoperative data. All patients were assessed by psychiatrists, and delirium was diagnosed according to criteria of the Diagnostic and Statistical Manual of Mental Disorders, fourth edition. Data were analyzed via univariate analysis and multivariate logistic regression.

Results The prevalence of postoperative delirium was 41.7%. Patients with and without delirium differed significantly on 29 variables. Four postoperative factors, hematocrit less than 30%, cardiogenic shock, hypoalbuminemia, and acute infection, were significant, independent predictors of postoperative delirium.

Conclusions The results of this study can be used to develop a revised checklist of 29 preoperative, intraoperative, and postoperative risk factors for delirium, with special attention to the 4 predictive postoperative factors. Use of such a checklist may facilitate the ability to prevent or detect delirium early and provide suitable treatment.

Incidence and predictors of post-cardiotomy delirium

OBJECTIVE

To determine the incidence and predictors of delirium after cardiac surgery.

METHOD

A prospective, observational study of postcardiotomy surgical patients was conducted during a 5 month period at the Minneapolis, MN, VAMC.

RESULTS

Of the 53 patients who completed the study, 12 patients (23%) met criteria for postoperative delirium and 18 patients (34%) met criteria for postoperative subsyndromal delirium. Significant predictors of postoperative delirium included a history of cerebrovascular disease (Charlson Index item, VA CICSP), high medical comorbidity (VA morbidity risk score, Charlson Index), increased preoperative creatinine level, and an increased preoperative pain rating. When delirium and subsyndromal delirium patients were combined, a history of cerebrovascular disease, left ventricular dysfunction, or diabetes predicted the development of delirious symptoms.

CONCLUSIONS

Incident delirium occurred in 23% of patients after cardiac surgery and incident delirium symptoms, in 57%. The strongest predictor of both incident delirium and delirium symptoms was a history of cerebrovascular disease.

Pre-operative mild cognitive dysfunction predicts risk for post-operative delirium after elective cardiac surgery

BACKGROUND AND AIMS

To identify pre-operative risk factors for delirium in patients undergoing elective cardiac surgery, using clearly defined diagnostic criteria for delirium, and a thorough clinical assessment.

METHODS

The incidence of post-operative delirium in 107 patients >or=60 years undergoing elective cardiac surgery was calculated. None of the patients included suffered from dementia. Pre-operative cognitive function in all patients was assessed using the Mini Mental State Examination (MMSE) and post-operative delirium was diagnosed using the Confusion Assessment Method (CAM). Post-operative clinical and cognitive assessments were carried out for all patients.

RESULTS

Twenty-five patients (23.4%) developed delirium post-operatively. Clinical parameters, including age, gender, co-morbidities, medications, and peri-operative parameters, were similar in patients with and without post-operative delirium. Patients with pre-operative subjective memory complaints and lower MMSE scores, undergoing valve operation or valve + coronary artery bypass grafting (CABG), exhibited an increased risk of developing post-operative delirium. Additionally, delirious patients had a significant decline in post-operative MMSE score compared with the non-delirious ones.

CONCLUSIONS

The main pre-operative risk factors for post-operative delirium after elective cardiac operations were subjective memory complaints, mild cognitive impairment, and type of cardiac surgery, such as valve procedures. This study suggests that cognitive evaluation should be included in pre-operative assessment.

Delirium: guidelines for general hospitals

OBJECTIVE

Delirium is highly prevalent in general hospitals but remains underrecognized and undertreated despite its association with increased morbidity, mortality, and health services utilization. To enhance its management, we developed guidelines covering all aspects, from risk factor identification to preventive, diagnostic, and therapeutic interventions in adult patients.

METHODS

Guidelines, systematic reviews, randomized controlled trials (RCT), and cohort studies were systematically searched and evaluated. Based on a synthesis of retrieved high-quality documents, recommendation items were submitted to a multidisciplinary expert panel. Experts scored the appropriateness of recommendation items, using an evidence-based, explicit, multidisciplinary panel approach. Each recommendation was graded according to this process' results.

RESULTS

Rated recommendations were mostly supported by a low level of evidence (1.3% RCT and systematic reviews, 14.3% nonrandomized trials vs. 84.4% observational studies or expert opinions). Nevertheless, 71.1% of recommendations were considered appropriate by the experts. Prevention of delirium and its nonpharmacological management should be fostered. Haloperidol remains the first-choice drug, whereas the role of atypical antipsychotics is still uncertain.

CONCLUSIONS

While many topics addressed in these guidelines have not yet been adequately studied, an explicit panel and evidence-based approach allowed the proposal of comprehensive recommendations for the prevention and management of delirium in general hospitals.

Occurrence and outcome of delirium in medical in-patients: a systematic literature review

BACKGROUND

Despite the acknowledged clinical importance of delirium, research evidence for measures to improve its management is sparse. A necessary first step to devising appropriate strategies is to understand how common it is and what its outcomes are in any particular setting.

OBJECTIVE

To determine the occurrence of delirium and its outcomes in medical in-patients, through a systematic review of the literature.

METHOD

We searched electronic medical databases, the Consultation-Liaison Literature Database and reference lists and bibliographies for potentially relevant studies. Studies were selected, quality assessed and data extracted according to preset protocols.

RESULTS

Results for the occurrence of delirium in medical in-patients were available for 42 cohorts. Prevalence of delirium at admission ranged from 10 to 31%, incidence of new delirium per admission ranged from 3 to 29% and occurrence rate per admission varied between 11 and 42%. Results for outcomes were available for 19 study cohorts. Delirium was associated with increased mortality at discharge and at 12 months, increased length of hospital stay (LOS) and institutionalisation. A significant proportion of patients had persistent symptoms of delirium at discharge and at 6 and 12 months.

CONCLUSION

Delirium is common in medical in-patients and has serious adverse effects on mortality, functional outcomes, LOS and institutionalisation. The development of appropriate strategies to improve its management should be a clinical and research priority. As delirium prevalent at hospital admission is a significant problem, research is also needed into preventative measures that could be applied in community settings.

Delirium in inpatients with respiratory diseases

The features of delirium in patients being hospitalized due to respiratory diseases were investigated. From the inpatients in the respiratory medical ward of Tokyo Metropolitan Hiroo General Hospital over the course of 1 year, the patients who had delirium were diagnosed by a semistructured interview. The total number of subjects was 454, and patients with delirium were 43. Various clinical factors were compared between the delirium group and non-delirium group. In the delirium group, there were many elderly patients of 70 years or older. Moreover, there were many patients who had a chronic respiratory disease, patients in which the respiratory diseases were mutually complicated, and patients in whom other diseases combined with the respiratory disease in the delirium group. There were also many patients in the Intensive Care Unit (ICU), and patients with an endotracheal intubation or extubation. Based on the results of a multiple logistic regression analysis, for age, ICU accommodation, and endotracheal intubation, the value of the delirium group was more significant than that of the non-delirium group. In half of the patients from the delirium group, delirium developed within 1 week after hospitalization. In the patients who died in the hospital, however, delirium often developed days after they had been hospitalized. It was suggested that the later developed delirium had a relation to the prognosis.

Coronary artery bypass grafting (CABG) and cognitive decline: a review

Coronary artery bypass grafting (CABG) is a worldwide used myocardial revascularization procedure, which despite the modern advantages still has a spectrum of complications. The relatively old age of the patients who undergo CABG and their widespread atherosclerotic disease are possible reasons for vascular sequels particularly those leading to neurological dysfunction. Immediate, early and late cognitive decline is a known- and well-defined outcome of CABG. Whereas a lot of data was collected through the last years regarding to neuropsychological dysfunction after CABG, nevertheless etiology and mechanisms of this phenomenon remain unresolved and they are probably multifactorial. Meticulously preoperative assessment of those patients with a potential risk of adverse neurocognitive outcomes can help clinicians to select the mode of revascularization and to better counsel patients about the risks and benefits of surgery versus more conservative kinds of treatment.

Predictors of delirium after cardiac surgery delirium: Effect of beating-heart (off-pump) surgery

BACKGROUND

Despite improved outcomes after cardiac operations, postoperative delirium remains a common complication that is associated with increased morbidity and prolonged hospital stay.

METHODS

Univariate and multivariate predictors of postoperative delirium were determined from prospectively gathered data on 16,184 patients undergoing cardiac operations with cardiopulmonary bypass (conventional, n = 14,342) and without cardiopulmonary bypass (beating-heart surgery, n = 1847) between April 1996 and August 2001. Delirium was defined as a transient mental syndrome of acute onset characterized by global impairment of cognitive functions, a reduced level of consciousness, attentional abnormalities, increased or decreased psychomotor activity, and a disordered sleep-wake cycle.

RESULTS

The overall prevalence of postoperative delirium was 8.4%. Of 49 selected patient-related risk factors and treatment variables, 35 were highly associated with postoperative delirium by univariate analysis. Stepwise logistic regression revealed the following variables as independent predictors of delirium: history of cerebrovascular disease, peripheral vascular disease, atrial fibrillation, diabetes mellitus, left ventricular ejection fraction of 30% or less, preoperative cardiogenic shock, urgent operation, intraoperative hemofiltration, operation time of 3 hours or more, and a high perioperative transfusion requirement. Two variables were identified as having a significant protective effect against postoperative delirium: beating-heart surgery and younger patient age.

CONCLUSIONS

Postoperative delirium is a common complication in cardiac operations. The increased use of beating-heart surgery without cardiopulmonary bypass may lead to a lower prevalence of this complication and thus improve patient outcomes.

Brain injury after adult cardiac surgery

Despite remarkable progress in surgical, cardiopulmonary bypass and anaesthetic techniques during the last three decades, brain damage remains an important complication of adult cardiac surgery. Effective brain protection strategies are already implemented today, but ongoing research is needed to meet the challenges faced in operating on increasingly old and disabled patients. The incidence of brain injury may be reduced by modifying the surgical procedure according to carotid duplex scanning and epiaortic echocardiography, by using techniques to reduce microembolization during cardiopulmonary bypass and by optimizing patient temperature during and after surgery. Increased knowledge will aid in choosing the best procedure or combination of procedures in each case to ensure that risks do not outweigh benefits.

Postoperative confusion assessed with the Short Portable Mental Status Questionnaire

BACKGROUND

Confusion is a common occurrence after cardiac surgery. However, there is great variability in the reported incidence of confusion in patients following cardiac surgery, mainly due to the diagnostic methods and instruments employed in assessing confusion.

METHODS

Forty-eight cardiac surgery patients were assessed for postoperative confusion by a non-structured physician interview, and by the short portable mental status questionnaire (SPMSQ) administered by a medical student.

RESULTS

The non-structured ward interviews detected confusion in one of the 48 patients (2%), whereas the SPMSQ diagnosed confusion in 15 of the 48 patients (31%).

CONCLUSION

Unlike a subjective ward interview, the SPMSQ is a brief and objective diagnostic tool that can be used to measure accurately both the presence and severity of confusion in postoperative cardiac surgery patients.

Risk factors for postoperative delirium in vascular surgery

The aim of this study was to identify psychiatric and somatic risk factors associated with the development, severity and duration of postoperative delirium after vascular surgery. Forty-seven patients underwent aortic, carotid artery and peripheral artery surgery. Both, surgeon and psychiatrist, monitored patients preoperatively with daily follow up. Preoperative psychiatric assessment included standardized psychopathological scales for the detection of psychiatric symptoms and cognitive deficits. We diagnosed delirium using DSM IV criteria. Delirium Rating Scale was used to estimate delirium severity. Surgical parameters included patient history, diagnoses, medication and laboratory parameters. A statistical analysis was performed using multivariate regression analyses to find factors significantly associated with delirium development, severity, and duration. Thirty-six percent of the patients developed postoperative delirium after surgery. Comparison of different parameters revealed that especially preoperative depression symptoms and perioperative transfusions/infusions had significant predictive value for the development as well as for the severity of postoperative delirium.

Anxiety, delirium, and pain in the intensive care unit

Anxiety, agitation, delirium, and pain are common findings in the ICU. These unhealthy states may lead to increased irritability, discomfort, hypertension, tachycardia, cardiac ischemia, harmful motor activity, and psychologic disquiet for the patient. The appropriate treatment of these conditions may lead to decreased morbidity and mortality in the critically ill patient. Unfortunately, the management of anxiety, agitation, delirium, and pain in the intensive care unit is not ideal. Many patients interviewed after an ICU stay rate their pain control as poor and their memories of their stay as unpleasant. Furthermore, many caregivers lack sufficient understanding of the appropriate or indicated uses of drugs to allay patients' fears and pain. The use of suitable protocols for the proper titration of sedation of mechanically ventilated patients and monitoring of the level of sedation in ventilated patients may decrease the amount of time that patients are ventilated and may alleviate some of the emotional stresses of recall of painful procedures or uncomfortable mechanical ventilation. Future research into protocols for the care of the critically ill patient can enhance the overall well-being of these patients.

Neurological and cognitive disorders after coronary artery bypass grafting

Cerebral injury is a major cause of mortality and morbidity of coronary artery bypass grafting. Stroke occurs in 3% of patients and is largely caused by embolization of atheromatous debris during manipulation of the diseased aorta. Cognitive impairment, which is predominantly caused by microembolization of gaseous and particulate matter, mainly generated by cardiotomy suction, is more common. Demonstration of similar cognitive impairment in patients operated on without cardiopulmonary bypass indicates that other pathophysiological mechanisms, such as anaesthesia and hypoperfusion, are also involved. Advances in medical, anesthetic, and surgical management have resulted in a reduction in the incidence of neurological injury in CABG patients over the past decade. On the other hand, an increasingly elderly population with more severe comorbidity, who are more prone to cerebral injury, are increasingly being referred for CABG. Possible mechanisms to reduce overt and subtle cerebral injury are discussed. The use of composite arterial grafts performed on the beating heart may be the most effective way of minimizing the risk of cerebral injury associated with CABG.

Evaluation of neurologic assessment and outcomes in cardiac surgical patients

It is well recognized that cardiac surgery with cardiopulmonary bypass can potentially induce a wide spectrum of central nervous system (CNS) sequelae. Our awareness of the prevalence of these CNS complications is dependent on the validity of the available diagnostic methods. Current assessment methods designed to detect both focal and diffuse cerebral ischemia include neurologic examination, imaging techniques, biochemical markers, neuropsychologic assessment, and patient perceived outcomes. These techniques vary in their sensitivity and specificity, as well as feasibility for use in everyday clinical practice. There are currently only limited standardized methodologic guidelines for the assessment of CNS complications after cardiac surgery, which has resulted in considerable interstudy variability in the identification and reporting of outcomes. The application of clearly definable endpoints for reporting of CNS outcomes would be beneficial. The wealth of available data suggests that the incidence of overt CNS injury such as stroke has declined since the 1980s and is now approximately 2%, whereas evidence suggests that up to one third of cardiac surgery patients experience postoperative cognitive deficits. One of the clear strengths of the current era is the recognition of CNS injury associated with cardiac surgery, and the quest to improve our understanding of these outcomes. The application of more uniform assessment and reporting practices is surely vital to the continued advancement of cardiac surgery.

Neurobehavioural sequelae of cardiopulmonary bypass

The development of coronary artery bypass grafting (CABG) and its effect on angina is the product of a series of technical and scientific advances. Despite these advances, however, adverse neurobehavioural outcomes continue to occur. Stroke is the most serious complication of CABG, but studies that have identified demographic and medical risk factors available before surgery are an important advance. Short-term cognitive deficits are common after CABG, but may not be specific to this procedure. However, deficits in some cognitive areas such as visuoconstruction persist over time, and may reflect parieto-occipital watershed area injury secondary to hypoperfusion or embolic factors. Risk factors for cognitive decline may be time dependent, with short-term studies identifying factors that differ from those of long-term studies. Patients with depression before surgery are likely to have persistent depression afterwards. However, depression does not account for the cognitive decline after CABG. Since CABG is increasingly done in older patients with more comorbidity, the challenge is to identify patients at risk of adverse neurocognitive outcomes and to protect them by modification of the surgical procedure or by effective medical therapy.

Incidence of and preoperative predictors for delirium after cardiac surgery

Incidence of and preoperative predictors for postoperative delirium were studied in 296 patients (age 26-83 years, mean age 63 years) undergoing elective cardiac surgery. Delirium occurred in 40 (13.5%) patients. Predictors included old age, low level of albumin, poor physical condition, use of nifedipine, and a high ratio of the amino acids phenylalanine to the sum of isoleucine, leucine, valine, tyrosine, and tryptophan. These findings suggest that preoperative physical condition and amino acid disturbances may be related to delirium after cardiac surgery in the elderly.

Early diagnosis of delirium after cardiac surgery

In order to detect patients who become delirious after cardiac surgery in an early postoperative stage, an observational checklist was used. Fifteen patients were constantly observed during their 48-hour stay at the intensive care unit for postoperative care. Two (13%) male patients developed postoperative delirium according to DSM-III-R criteria. It was possible to detect these patients in an early postoperative stage (within 48 hours) by means of systematic observations of their behavior.