Chronic neurocognitive effects of critical illness

European Working Group on SARS-CoV-2: Current Understanding, Unknowns, and Recommendations on the Neurological Complications of COVID-19

The emergence of COVID-19 was rapidly followed by infection and the deaths of millions of people across the globe. With much of the research and scientific advancement rightly focused on reducing the burden of severe and critical acute COVID-19 infection, the long-term effects endured by those who survived the acute infection has been previously overlooked. Now, an appreciation for the post-COVID-19 condition, including its neurological manifestations, is growing, although there remain many unknowns regarding the aetiology and risk factors of the condition, as well as how to effectively diagnose and treat it. Here, drawing upon the experiences and expertise of the clinicians and academics of the European working group on COVID-19, we have reviewed the current literature to provide a comprehensive overview of the neurological sequalae of the post-COVID-19 condition. In this review, we provide a summary of the neurological symptoms associated with the post-COVID-19 condition, before discussing the possible mechanisms which may underly and manifest these symptoms. Following this, we explore the risk factors for developing neurological symptoms as a result of COVID-19 and the post-COVID-19 condition, as well as how COVID-19 infection may itself be a risk factor for the development of neurological disease in the future. Lastly, we evaluate how the post-COVID condition could be accurately diagnosed and effectively treated, including examples of the current guidelines, clinical outcomes and tools that have been developed to aid in this process, as well as addressing the protection provided by COVID-19 vaccines against post-COVID-19 condition. Overall, this review provides a comprehensive overview of the neurological sequalae of the post-COVID-19 condition.

Quantitative EEG During Critical Illness Correlates with Patterns of Long-Term Cognitive Impairment

OBJECTIVE

Many intensive care unit (ICU) survivors suffer disabling long-term cognitive impairment (LTCI) after critical illness. We compared EEG characteristics during critical illness with patients' 1-year neuropsychological outcomes.

METHODS

We performed a post hoc analysis of patients in the BRAIN-ICU study who had undergone EEG for clinical purposes during admission (n = 10). All survivors underwent formal cognitive assessments at 12-month follow-up. We evaluated EEGs by conventional visual inspection and computed 10 quantitative features. We explored associations between EEG and patterns of LTCI using Wilcoxon rank-sum tests and Spearman's rank correlations.

RESULTS

Of 521 Vanderbilt patients enrolled in the parent study, 24 had EEG recordings during admission. Ten survivors had EEG tracings available and completed follow-up cognitive testing. All but one inpatient EEG showed generalized background slowing. All patients demonstrated cognitive impairment in at least one domain at follow-up. The most common deficits occurred in delayed memory (DM-median index 62) and visuospatial/constructional (VC-median index 69) domains. Relative alpha power correlated with VC score (ρ = 0.78, P = .008). Peak interhemispheric coherence correlated negatively with DM (ρ = -0.81, P = .018).

CONCLUSIONS

Quantitative EEG features during critical illness correlated with domain-specific cognitive performance in our small cohort of ICU survivors. Further study in larger prospective cohorts is required to determine whether these relationships hold.

SIGNIFICANCE

EEG may serve as a prognostic biomarker predicting patterns of long-term cognitive impairment.

Elevation of neural injury markers in patients with neurologic sequelae after hospitalization for SARS-CoV-2 infection

Patients with SARS-CoV-2 infection (COVID-19) risk developing long-term neurologic symptoms after infection. Here, we identify biomarkers associated with neurologic sequelae one year after hospitalization for SARS-CoV-2 infection. SARS-CoV-2-positive patients were followed using post-SARS-CoV-2 online questionnaires and virtual visits. Hospitalized adults from the pre-SARS-CoV-2 era served as historical controls. 40% of hospitalized patients develop neurological sequelae in the year after recovery from acute COVID-19 infection. Age, disease severity, and COVID-19 infection itself was associated with additional risk for neurological sequelae in our cohorts. Glial fibrillary astrocytic protein (GFAP) and neurofilament light chain (NF-L) were significantly elevated in SARS-CoV-2 infection. After adjusting for age, sex, and disease severity, GFAP and NF-L remained significantly associated with longer term neurological symptoms in patients with SARS-CoV-2 infection. GFAP and NF-L warrant exploration as biomarkers for long-term neurologic complications after SARS-CoV-2 infection.

ARDS associated acute brain injury: from the lung to the brain

A complex interrelation between lung and brain in patients with acute lung injury (ALI) has been established by experimental and clinical studies during the last decades. Although, acute brain injury represents one of the most common insufficiencies in patients with ALI and acute respiratory distress syndrome (ARDS), the underlying pathophysiology of the observed crosstalk remains poorly understood due to its complexity. Specifically, it involves numerous pathophysiological parameters such as hypoxemia, neurological adverse events of lung protective ventilation, hypotension, disruption of the BBB, and neuroinflammation in such a manner that the brain of ARDS patients-especially hippocampus-becomes very vulnerable to develop secondary lung-mediated acute brain injury. A protective ventilator strategy could reduce or even minimize further systemic release of inflammatory mediators and thus maintain brain homeostasis. On the other hand, mechanical ventilation with low tidal volumes may lead to self-inflicted lung injury, hypercapnia and subsequent cerebral vasodilatation, increased cerebral blood flow, and intracranial hypertension. Therefore, by describing the pathophysiology of ARDS-associated acute brain injury we aim to highlight and discuss the possible influence of mechanical ventilation on ALI-associated acute brain injury.

Chronic critical illness and post-intensive care syndrome: from pathophysiology to clinical challenges

Background

Post‐intensive care syndrome (PICS) encompasses physical, cognition, and mental impairments persisting after intensive care unit (ICU) discharge. Ultimately it significantly impacts the long‐term prognosis, both in functional outcomes and survival. Thus, survivors often develop permanent disabilities, consume a lot of healthcare resources, and may experience prolonged suffering. This review aims to present the multiple facets of the PICS, decipher its underlying mechanisms, and highlight future research directions.

Main text

This review abridges the translational data underlying the multiple facets of chronic critical illness (CCI) and PICS. We focus first on ICU-acquired weakness, a syndrome characterized by impaired contractility, muscle wasting, and persisting muscle atrophy during the recovery phase, which involves anabolic resistance, impaired capacity of regeneration, mitochondrial dysfunction, and abnormalities in calcium homeostasis. Second, we discuss the clinical relevance of post-ICU cognitive impairment and neuropsychological disability, its association with delirium during the ICU stay, and the putative role of low-grade long-lasting inflammation. Third, we describe the profound and persistent qualitative and quantitative alteration of the innate and adaptive response. Fourth, we discuss the biological mechanisms of the progression from acute to chronic kidney injury, opening the field for renoprotective strategies. Fifth, we report long-lasting pulmonary consequences of ARDS and prolonged mechanical ventilation. Finally, we discuss several specificities in children, including the influence of the child’s pre-ICU condition, development, and maturation.

Conclusions

Recent understandings of the biological substratum of the PICS’ distinct features highlight the need to rethink our patient trajectories in the long term. A better knowledge of this syndrome and precipitating factors is necessary to develop protocols and strategies to alleviate the CCI and PICS and ultimately improve patient recovery.

Attention profile of physically recovered COVID-19 inpatients on the day of discharge

Few studies have reported specific attention deficits in post-COVID-19 patients. Attention consists of different subdomains. Disruptions to specific attention subdomains might impair a wide range of everyday tasks, including road safety. As there are millions of COVID-19 patients with different socio-economic backgrounds, screening of attentional performance less dependent on education is needed. Here, we verified if physically recovered COVID-19 inpatients showed specific attention decrements at discharge. The Continuous Visual Attention Test (CVAT) is a Go/No-go task which is independent of participants' schooling. It detects visuomotor reaction time (RT = intrinsic alertness), variability of reaction time (VRT = sustained attention), omission (focused-attention), and commission errors (response-inhibition). Thirty physically functional COVID-19 inpatients at discharge and 30 non-infected controls underwent the CVAT. A MANCOVA was performed to examine differences between controls and patients, followed by post-hoc ANCOVAs. Then, we identified the percentile score for each patient within the distribution of the CVAT performance of 211 subjects mentally capable of driving (reference group). COVID-19 patients at discharge showed greater RT and VRT, and more omission errors than controls. Twenty-two patients (73%) had performance below the 5th percentile of the reference group in one or more subdomains. As slow visuomotor RT, deficits in focusing and difficulties in keeping visual attention are associated with traffic accidents, we concluded that most COVID-19 patients at discharge had deficits that may increase the risk of road injuries. As these deficits will probably affect other daily activities, a routine assessment with the CVAT could provide useful information on whom to send to post-COVID centers.

Lung-brain 'cross-talk': systemic propagation of cytokines in the ARDS via the bloodstream using a blood transfusion model does not influence cerebral inflammatory response in pigs

Background

Interorgan cross-talk describes the phenomenon in which a primarily injured organ causes secondary damage to a distant organ. This cross-talk is well known between the lung and brain. One theory suggests that the release and systemic distribution of cytokines via the bloodstream from the primarily affected organ sets in motion proinflammatory cascades in distant organs. In this study, we analysed the role of the systemic distribution of cytokines via the bloodstream in a porcine ARDS model for organ cross-talk and possible inflammatory changes in the brain.

Methods

After approval of the State and Institutional Animal Care Committee, acute respiratory distress syndrome (ARDS) induction with oleic acid injection was performed in seven animals. Eight hours after ARDS induction, blood (35-40 ml kg^-1) was taken from these seven 'ARDS donor' pigs. The collected 'ARDS donor' blood was transfused into seven healthy 'ARDS-recipient' pigs. Three animals served as a control group, and blood from these animals was transfused into three healthy pigs after an appropriate ventilation period. All animals were monitored for 8 h using advanced cardiorespiratory monitoring. Postmortem assessment included cerebral (hippocampal and cortex) mediators of early inflammatory response (IL-6, TNF-alpha, iNOS, sLCN-2), wet-to-dry ratio and lung histology. TNF-alpha serum concentration was measured in all groups.

Results

ARDS was successfully induced in the 'ARDS donor' group, and serum TNF-alpha levels were elevated compared with the 'ARDS-recipient' group. In the 'ARDS-recipient' group, neither significant ARDS alterations nor upregulation of inflammatory mediators in the brain tissue were detected after high-volume random allogenic 'ARDS-blood' transfusion. The role of the systemic distribution of inflammatory cytokines from one affected organ to another could not be confirmed in this study.

Association of Job Characteristics and Functional Impairments on Return to Work After ARDS

BACKGROUND

Joblessness is common after ARDS, but related risk factors are not fully understood.

RESEARCH QUESTION

What is the association between survivors' pre-ARDS workload and post-ARDS functional impairment, pain, and fatigue with their return to work (RTW) status?

STUDY DESIGN AND METHODS

The U.S. Occupational Information Network (O∗NET) was used to determine pre-ARDS workload for participants in the ARDS Network Long-Term Outcomes Study (ALTOS). Post-ARDS functional impairment was assessed using the Mini-Mental State Examination and SF-36 Physical Functioning, Social Functioning, and Mental Health sub-scales, and categorized as either no impairments, only psychosocial impairment, physical with low psychosocial impairment, or physical with high psychosocial impairment. Post-ARDS pain and fatigue were assessed using the SF-36 pain item and Functional Assessment of Chronic Illness Therapy-Fatigue Scale fatigue scale, respectively. Generalized linear mixed modeling methods were used to evaluate associations among pre-ARDS workload, post-ARDS functional impairment, and symptoms of pain and fatigue with post-ARDS RTW.

RESULTS

Pre-ARDS workload was not associated with post-ARDS RTW. However, as compared with survivors with no functional impairment, those with only psychosocial impairment (OR [CI]: 0.18 [0.06-0.50]), as well as physical impairment plus either low psychosocial impairment (0.08 [0.03-0.22]) or high psychosocial impairment (0.01 [0.003-0.05]) had lower odds of working. Pain (0.06 [0.03-0.14]) and fatigue (0.07 [0.03-0.16]) were also negatively associated with RTW.

INTERPRETATION

For previously employed survivors of ARDS, post-ARDS psychosocial and physical impairments, pain, and fatigue were negatively associated with RTW, whereas pre-ARDS workload was not associated. These findings are important for designing and implementing vocational interventions for ARDS survivors.

Acute Respiratory Failure Survivors' Physical, Cognitive, and Mental Health Outcomes: Quantitative Measures versus Semistructured Interviews

Rationale: Increasingly, patients are surviving acute respiratory failure (ARF), prompting the need to better understand standardized outcome measures commonly used during ARF follow-up studies. Objectives: Investigate standardized outcome measures (patient-reported physical and mental health measures, and cognitive testing) compared with findings from semistructured, qualitative interviews. Methods: As part of two ARF multicenter follow-up studies, standardized outcome measures were obtained, followed by qualitative evaluation via an in-depth, semistructured interview conducted and coded by two independent researchers. Qualitative interviews revealed the following post-ARF survivorship themes: physical impairment; anxiety, depression, and post-traumatic stress disorder symptoms; and cognitive impairment. Scores from standardized measures related to these themes were compared for ARF survivors reporting versus not reporting these themes in their qualitative interviews. Results: Of 59 invited ARF survivors, 48 (81%) completed both standardized outcome measures and qualitative interviews. Participants' median (interquartile range) age was 53 (43-64) years; 54% were female, and 88% were living independently before hospitalization. The two independent reviewers classifying the presence or absence of themes from the qualitative interviews had excellent agreement (κ = 0.80). There were significantly worse scores on standardized outcome measures for survivors reporting (vs. not reporting) physical and mental health impairments in their qualitative interviews. However, standardized cognitive test scores did not differ between patients reporting versus not reporting cognitive impairments in their qualitative interviews. Conclusions: These findings support the use of recommended, commonly used standardized outcome measures for physical and mental health impairments in ARF survivorship research. However, caution is needed in interpreting self-reported cognitive function compared with standardized cognitive testing.

Perioperative Research into Memory (PRiMe): Cognitive impairment following a severe burn injury and critical care admission, part 1

INTRODUCTION

An investigation into long-term cognitive impairment and Quality of Life (QoL) after severe burns.

METHODS

A proof of principle, cohort design, prospective, observational clinical study. Patients with severe burns (>15% TBSA) admitted to Burns ICU for invasive ventilation were recruited for psychocognitive assessment with a convenience sample of age and sex-matched controls. Participants completed psychological and QoL questionnaires, the Cogstate^® electronic battery, Hopkins Verbal Learning, Verbal Fluency and Trail making tasks.

RESULTS

15 patients (11M, 4F; 41±14 years; TBSA 38.4%±18.5) and comparators (11M, 4F; 40±13 years) were recruited. Burns patients reported worse QoL (Neuro-QoL Short Form v2, patient 30.1±8.2, control 38.7±3.2, p=0.0004) and cognitive function (patient composite z-score 0.01, IQR -0.11 to 0.33, control 0.13, IQR 0.47-0.73, p=0.02). Compared to estimated premorbid FSIQ, patients dropped an equivalent of 8 IQ points (p=0.002). Cognitive function negatively correlated with burn severity (rBaux score, p=0.04). QoL strongly correlated with depressive symptoms (Rho=-0.67, p=0.009) but not cognitive function.

CONCLUSIONS

Severe burns injuries are associated with a significant, global, cognitive deficit. Patients also report worse QoL, depression and post-traumatic stress. Perceived QoL from cognitive impairment was more closely associated with depression than cognitive impairment.

Coronary Artery Bypass Graft Operation: Patients' Experience of Health and Well-Being Over Time

BACKGROUND

The aim of the coronary artery bypass graft operation is to relieve anginal symptoms and improve functional ability, quality of life and survival. However, having the surgery does not always have the desired outcomes. Although numerous studies have investigated the outcomes of coronary artery bypass graft operation, little attention has been given to patients' perceptions of the outcomes or effects of the operation on health and well-being over time.

AIM

To explore patients' perspectives on the effects of coronary artery bypass surgery on health and well-being over time.

METHODS

As part of a larger mixed methods study, 62 in-depth audio-taped interviews with men and women who had undergone coronary artery bypass approximately 7 years earlier were conducted. Interviews were audio-taped and transcribed. Data were analysed thematically. This paper reports the findings from the qualitative component of the larger study.

FINDINGS

The four main themes: 'Recovery and Rehabilitation', 'Seven Years On', 'Maintaining a Positive Approach', and 'Health Behaviour Change' reflect the main areas of focus emerging across the interviews and provide credible overarching descriptors of the sub-themes they encompass. The 11 sub-themes identified were recognised as central to the patients' experiences of their health and well-being over the longer-term.

CONCLUSIONS

Although most patients report improved health and well-being after coronary artery bypass operation, many have described their recovery and rehabilitation as a complex process with both short and long term effects. The insights provided by participants help improve our understanding of the impact of the operation on patients' health and well-being over time. We believe these insights will help us to anticipate the possible needs of future patients and enable us develop appropriate interventions that may facilitate self-management for optimal recovery and health maintenance.

Feasibility of a multiple-choice mini mental state examination for chronically critically ill patients

OBJECTIVES

Following treatment in an ICU, up to 70% of chronically critically ill patients present neurocognitive impairment that can have negative effects on their quality of life, daily activities, and return to work. The Mini Mental State Examination is a simple, widely used tool for neurocognitive assessment. Although of interest when evaluating ICU patients, the current version is restricted to patients who are able to speak. This study aimed to evaluate the feasibility of a visual, multiple-choice Mini Mental State Examination for ICU patients who are unable to speak.

DESIGN

The multiple-choice Mini Mental State Examination and the standard Mini Mental State Examination were compared across three different speaking populations. The interrater and intrarater reliabilities of the multiple-choice Mini Mental State Examination were tested on both intubated and tracheostomized ICU patients.

SETTING

Mixed 36-bed ICU and neuropsychology department in a university hospital.

SUBJECTS

Twenty-six healthy volunteers, 20 neurological patients, 46 ICU patients able to speak, and 30 intubated or tracheostomized ICU patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Multiple-choice Mini Mental State Examination results correlated satisfactorily with standard Mini Mental State Examination results in all three speaking groups: healthy volunteers: intraclass correlation coefficient = 0.43 (95% CI, -0.18 to 0.62); neurology patients: 0.90 (95% CI, 0.82-0.95); and ICU patients able to speak: 0.86 (95% CI, 0.70-0.92). The interrater and intrarater reliabilities were good (0.95 [0.87-0.98] and 0.94 [0.31-0.99], respectively). In all populations, a Bland-Altman analysis showed systematically higher scores using the multiple-choice Mini Mental State Examination.

CONCLUSIONS

Administration of the multiple-choice Mini Mental State Examination to ICU patients was straightforward and produced exploitable results comparable to those of the standard Mini Mental State Examination. It should be of interest for the assessment and monitoring of the neurocognitive performance of chronically critically ill patients during and after their ICU stay. The multiple-choice Mini Mental State Examination tool's role in neurorehabilitation and its utility in monitoring neurocognitive functions in ICU should be assessed in future studies.

Recall of ICU Stay in Patients Managed With a Sedation Protocol or a Sedation Protocol With Daily Interruption

OBJECTIVES

To 1) describe factual, emotional, and delusional memories of ICU stay for patients enrolled in the SLEAP (Daily sedation interruption in mechanically ventilated critically ill patients cared for with a sedation protocol) trial; 2) compare characteristics of patients with and without ICU recall, and patients with and without delusional memories; and 3) determine factors associated with delusional memories 28 days after ICU discharge.

DESIGN

Prospective cohort.

SETTING

Sixteen North American medical and surgical ICUs.

PATIENTS

Critically ill, mechanically ventilated adults randomized in the SLEAP trial.

INTERVENTIONS

Post-ICU interviews on days 3, 28, and 90 using the validated ICU Memory Tool.

MEASUREMENTS AND MAIN RESULTS

Overall, 289 of 297 ICU survivors (97%) (146 protocolized sedation and 143 protocolized sedation plus daily interruption patients) were interviewed at least once. Because there were no differences in recall status or types of memories between the two sedation groups, we present the findings for all patients rather than by study group. On days 3, 28, and 90, 28%, 26%, and 36% of patients, respectively, reported no recall of being in the ICU (overall perception, self-reported) (p = 0.75). Mean daily doses of benzodiazepines and opioids were lower in patients with no ICU recall than those with recall (p < 0.0001 for both). Despite one third of patients reporting no recall of ICU stay on day 3, 97% and 90% reported at least one factual and one emotional memory from ICU, respectively. Emotional memories declined with time after ICU discharge, particularly panic and confusion. Delusional memories 28 days after discharge were common (70%) yet unrelated to delirium (p = 0.84), recall status (p = 0.15), total dose of benzodiazepine (p = 0.78), or opioid (p = 0.21). Delusional memories were less likely with longer duration of mechanical ventilation (odds ratio, 0.955; 95% CI, 0.91-1.00; p = 0.04).

CONCLUSIONS

Recall of ICU stay and types of memories reported were not influenced by the trial sedation strategy. Lack of ICU recall and delusional memories were common after ICU discharge despite the use of sedation strategies that promoted wakefulness.

Brain-lung crosstalk: Implications for neurocritical care patients

Major pulmonary disorders may occur after brain injuries as ventilator-associated pneumonia, acute respiratory distress syndrome or neurogenic pulmonary edema. They are key points for the management of brain-injured patients because respiratory failure and mechanical ventilation seem to be a risk factor for increased mortality, poor neurological outcome and longer intensive care unit or hospital length of stay. Brain and lung strongly interact via complex pathways from the brain to the lung but also from the lung to the brain. Several hypotheses have been proposed with a particular interest for the recently described “double hit” model. Ventilator setting in brain-injured patients with lung injuries has been poorly studied and intensivists are often fearful to use some parts of protective ventilation in patients with brain injury. This review aims to describe the epidemiology and pathophysiology of lung injuries in brain-injured patients, but also the impact of different modalities of mechanical ventilation on the brain in the context of acute brain injury.

Exercise rehabilitation following intensive care unit discharge for recovery from critical illness

BACKGROUND

Skeletal muscle wasting and weakness are significant complications of critical illness, associated with degree of illness severity and periods of reduced mobility during mechanical ventilation. They contribute to the profound physical and functional deficits observed in survivors. These impairments may persist for many years following discharge from the intensive care unit (ICU) and can markedly influence health-related quality of life. Rehabilitation is a key strategy in the recovery of patients after critical illness. Exercise-based interventions are aimed at targeting this muscle wasting and weakness. Physical rehabilitation delivered during ICU admission has been systematically evaluated and shown to be beneficial. However, its effectiveness when initiated after ICU discharge has yet to be established.

OBJECTIVES

To assess the effectiveness of exercise rehabilitation programmes, initiated after ICU discharge, for functional exercise capacity and health-related quality of life in adult ICU survivors who have been mechanically ventilated longer than 24 hours.

SEARCH METHODS

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid SP MEDLINE, Ovid SP EMBASE and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) via EBSCO host to 15 May 2014. We used a specific search strategy for each database. This included synonyms for ICU and critical illness, exercise training and rehabilitation. We searched the reference lists of included studies and contacted primary authors to obtain further information regarding potentially eligible studies. We also searched major clinical trials registries (Clinical Trials and Current Controlled Trials) and the personal libraries of the review authors. We applied no language or publication restriction. We reran the search in February 2015 and will deal with the three studies of interest when we update the review.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-RCTs and controlled clinical trials (CCTs) that compared an exercise intervention initiated after ICU discharge versus any other intervention or a control or 'usual care' programme in adult (≥ 18 years) survivors of critical illness.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by the Cochrane Collaboration.

MAIN RESULTS

We included six trials (483 adult ICU participants). Exercise-based interventions were delivered on the ward in two studies; both on the ward and in the community in one study; and in the community in three studies. The duration of the intervention varied according to length of hospital stay following ICU discharge (up to a fixed duration of 12 weeks).Risk of bias was variable for all domains across all trials. High risk of bias was evident in all studies for performance bias, although blinding of participants and personnel in therapeutic rehabilitation trials can be pragmatically challenging. For other domains, at least half of the studies were at low risk of bias. One study was at high risk of selection bias, attrition bias and other sources of bias. Risk of bias was unclear for the remaining studies across domains. We decided not to undertake a meta-analysis because of variation in study design, types of interventions and outcome measurements. We present a narrative description of individual studies for each outcome.All six studies assessed functional exercise capacity, although we noted wide variability in the nature of interventions, outcome measures and associated metrics and data reporting. Overall quality of the evidence was very low. Individually, three studies reported positive results in favour of the intervention. One study found a small short-term benefit in anaerobic threshold (mean difference (MD) 1.8 mL O2/kg/min, 95% confidence interval (CI) 0.4 to 3.2; P value = 0.02). In a second study, both incremental (MD 4.7, 95% CI 1.69 to 7.75 watts; P value = 0.003) and endurance (MD 4.12, 95% CI 0.68 to 7.56 minutes; P value = 0.021) exercise testing results were improved with intervention. Finally self reported physical function increased significantly following use of a rehabilitation manual (P value = 0.006). Remaining studies found no effect of the intervention.Similar variability was evident with regard to findings for the primary outcome of health-related quality of life. Only two studies evaluated this outcome. Individually, neither study reported differences between intervention and control groups for health-related quality of life due to the intervention. Overall quality of the evidence was very low.Four studies reported rates of withdrawal, which ranged from 0% to 26.5% in control groups, and from 8.2% to 27.6% in intervention groups. The quality of evidence for the effect of the intervention on withdrawal was low. Very low-quality evidence showed rates of adherence with the intervention. Mortality ranging from 0% to 18.8% was reported by all studies. The quality of evidence for the effect of the intervention on mortality was low. Loss to follow-up, as reported in all studies, ranged from 0% to 14% in control groups, and from 0% to 12.5% in intervention groups, with low quality of evidence. Only one non-mortality adverse event was reported across all participants in all studies (a minor musculoskeletal injury), and the quality of the evidence was low.

AUTHORS' CONCLUSIONS

At this time, we are unable to determine an overall effect on functional exercise capacity, or on health-related quality of life, of an exercise-based intervention initiated after ICU discharge for survivors of critical illness. Meta-analysis of findings was not appropriate because the number of studies and the quantity of data were insufficient. Individual study findings were inconsistent. Some studies reported a beneficial effect of the intervention on functional exercise capacity, and others did not. No effect on health-related quality of life was reported. Methodological rigour was lacking across several domains, influencing the quality of the evidence. Wide variability was noted in the characteristics of interventions, outcome measures and associated metrics and data reporting.If further trials are identified, we may be able to determine the effects of exercise-based intervention following ICU discharge on functional exercise capacity and health-related quality of life among survivors of critical illness.

Cognitive functioning, mental health, and quality of life in ICU survivors: an overview

Critical illness can and often does lead to significant cognitive impairment and to the development of psychological disorders. These conditions are persistent and, although they improve with time, often fail to completely abate. Although the functional correlates of cognitive and psychological morbidity (depression, anxiety, and posttraumatic stress disorder) have been studied, they may include poor quality of life, inability to return to work or to work at previously established levels, and inability to function effectively in emotional and interpersonal domains. The potential etiologies of cognitive impairment and psychological morbidity in ICU survivors are particularly poorly understood and may vary widely across patients. Potential contributors may include the potentially toxic effects of sedatives and narcotics, delirium, hypoxia, glucose dysregulation, metabolic derangements, and inflammation. Patients with preexisting vulnerabilities, including predisposing genetic factors, and frail elderly populations may be at particular risk for emergence of acceleration of conditions such as mild cognitive impairment.

A rehabilitation intervention to promote physical recovery following intensive care: a detailed description of construct development, rationale and content together with proposed taxonomy to capture processes in a randomised controlled trial

BACKGROUND

Increasing numbers of patients are surviving critical illness, but survival may be associated with a constellation of physical and psychological sequelae that can cause ongoing disability and reduced health-related quality of life. Limited evidence currently exists to guide the optimum structure, timing, and content of rehabilitation programmes. There is a need to both develop and evaluate interventions to support and expedite recovery during the post-ICU discharge period. This paper describes the construct development for a complex rehabilitation intervention intended to promote physical recovery following critical illness. The intervention is currently being evaluated in a randomised trial (ISRCTN09412438; funder Chief Scientists Office, Scotland).

METHODS

The intervention was developed using the Medical Research Council (MRC) framework for developing complex healthcare interventions. We ensured representation from a wide variety of stakeholders including content experts from multiple specialties, methodologists, and patient representation. The intervention construct was initially based on literature review, local observational and audit work, qualitative studies with ICU survivors, and brainstorming activities. Iterative refinement was aided by the publication of a National Institute for Health and Care Excellence guideline (No. 83), publicly available patient stories (Healthtalkonline), a stakeholder event in collaboration with the James Lind Alliance, and local piloting. Modelling and further work involved a feasibility trial and development of a novel generic rehabilitation assistant (GRA) role. Several rounds of external peer review during successive funding applications also contributed to development.

RESULTS

The final construct for the complex intervention involved a dedicated GRA trained to pre-defined competencies across multiple rehabilitation domains (physiotherapy, dietetics, occupational therapy, and speech/language therapy), with specific training in post-critical illness issues. The intervention was from ICU discharge to 3 months post-discharge, including inpatient and post-hospital discharge elements. Clear strategies to provide information to patients/families were included. A detailed taxonomy was developed to define and describe the processes undertaken, and capture them during the trial. The detailed process measure description, together with a range of patient, health service, and economic outcomes were successfully mapped on to the modified CONSORT recommendations for reporting non-pharmacologic trial interventions.

CONCLUSIONS

The MRC complex intervention framework was an effective guide to developing a novel post-ICU rehabilitation intervention. Combining a clearly defined new healthcare role with a detailed taxonomy of process and activity enabled the intervention to be clearly described for the purpose of trial delivery and reporting. These data will be useful when interpreting the results of the randomised trial, will increase internal and external trial validity, and help others implement the intervention if the intervention proves clinically and cost effective.

Prediction of P300 BCI aptitude in severe motor impairment

Brain-computer interfaces (BCIs) provide a non-muscular communication channel for persons with severe motor impairments. Previous studies have shown that the aptitude with which a BCI can be controlled varies from person to person. A reliable predictor of performance could facilitate selection of a suitable BCI paradigm. Eleven severely motor impaired participants performed three sessions of a P300 BCI web browsing task. Before each session auditory oddball data were collected to predict the BCI aptitude of the participants exhibited in the current session. We found a strong relationship of early positive and negative potentials around 200 ms (elicited with the auditory oddball task) with performance. The amplitude of the P2 (r  =  −0.77) and of the N2 (r  =  −0.86) had the strongest correlations. Aptitude prediction using an auditory oddball was successful. The finding that the N2 amplitude is a stronger predictor of performance than P3 amplitude was reproduced after initially showing this effect with a healthy sample of BCI users. This will reduce strain on the end-users by minimizing the time needed to find suitable paradigms and inspire new approaches to improve performance.

Nitrone-based therapeutics for neurodegenerative diseases: their use alone or in combination with lanthionines

The possibility of free radical reactions occurring in biological processes led to the development and employment of novel methods and techniques focused on determining their existence and importance in normal and pathological conditions. For this reason the use of nitrones for spin trapping free radicals became widespread in the 1970s and 1980s, when surprisingly the first evidence of their potent biological properties was noted. Since then widespread exploration and demonstration of the potent biological properties of phenyl-tert-butylnitrone (PBN) and its derivatives took place in preclinical models of septic shock and then in experimental stroke. The most extensive commercial effort made to capitalize on the potent properties of the PBN-nitrones was for acute ischemic stroke. This occurred during 1993-2006, when the 2,4-disulfonylphenyl PBN derivative, called NXY-059 in the stroke studies, was shown to be safe in humans and was taken all the way through clinical phase 3 trials and then was deemed to be ineffective. As summarized in this review, because of its excellent human safety profile, 2,4-disulfonylphenyl PBN, now called OKN-007 in the cancer studies, was tested as an anti-cancer agent in several preclinical glioma models and shown to be very effective. Based on these studies this compound is now scheduled to enter into early clinical trials for astrocytoma/glioblastoma multiforme this year. The potential use of OKN-007 in combination with neurotropic compounds such as the lanthionine ketamine esters is discussed for glioblastoma multiforme as well as for various other indications leading to dementia, such as aging, septic shock, and malaria infections. There is much more research and development activity ongoing for various indications with the nitrones, alone or in combination with other active compounds, as briefly noted in this review.

Exercise rehabilitation following hospital discharge in survivors of critical illness: an integrative review

Although clinical trials have shown benefit from early rehabilitation within the ICU, rehabilitation of patients following critical illness is increasingly acknowledged as an area of clinical importance. However, despite recommendations from published guidelines for rehabilitation to continue following hospital discharge, there is limited evidence to underpin practice during this intermediate stage of recovery. Those patients with ICU-acquired weakness on discharge from the ICU are most likely to benefit from ongoing rehabilitation. Despite this, screening based on strength alone may fail to account for the associated level of physical functioning, which may not correlate with muscle strength, nor address non-physical complications of critical illness. The aim of this review was to consider which patients are likely to require rehabilitation following critical illness and to perform an integrative review of the available evidence of content and nature of exercise rehabilitation programmes for survivors of critical illness following hospital discharge. Literature databases and clinical trials registries were searched using appropriate terms and groups of terms. Inclusion criteria specified the reporting of rehabilitation programmes for patients following critical illness post-hospital discharge. Ten items, including data from published studies and protocols from trial registries, were included. Because of the variability in study methodology and inadequate level of detail of reported exercise prescription, at present there can be no clear recommendations for clinical practice from this review. As this area of clinical practice remains in its relative infancy, further evidence is required both to identify which patients are most likely to benefit and to determine the optimum content and format of exercise rehabilitation programmes for patients following critical illness post-hospital discharge.

Sleep deprivation in critical illness: its role in physical and psychological recovery

Critically ill patients frequently experience poor sleep, characterized by frequent disruptions, loss of circadian rhythms, and a paucity of time spent in restorative sleep stages. Factors that are associated with sleep disruption in the intensive care unit (ICU) include patient-ventilator dysynchrony, medications, patient care interactions, and environmental noise and light. As the field of critical care increasingly focuses on patients' physical and psychological outcomes following critical illness, understanding the potential contribution of ICU-related sleep disruption on patient recovery is an important area of investigation. This review article summarizes the literature regarding sleep architecture and measurement in the critically ill, causes of ICU sleep fragmentation, and potential implications of ICU-related sleep disruption on patients' recovery from critical illness. With this background information, strategies to optimize sleep in the ICU are also discussed.

A longitudinal qualitative exploration of healthcare and informal support needs among survivors of critical illness: the RELINQUISH protocol

INTRODUCTION AND BACKGROUND

Survival following critical illness is associated with a significant burden of physical, emotional and psychosocial morbidity. Recovery can be protracted and incomplete, with important and sustained effects upon everyday life, including family life, social participation and return to work. In stark contrast with other critically ill patient groups (eg, those following cardiothoracic surgery), there are comparatively few interventional studies of rehabilitation among the general intensive care unit patient population. This paper outlines the protocol for a sub study of the RECOVER study: a randomised controlled trial evaluating a complex intervention of enhanced ward-based rehabilitation for patients following discharge from intensive care.

METHODS AND ANALYSIS

The RELINQUISH study is a nested longitudinal, qualitative study of family support and perceived healthcare needs among RECOVER participants at key stages of the recovery process and at up to 1 year following hospital discharge. Its central premise is that recovery is a dynamic process wherein patients' needs evolve over time. RELINQUISH is novel in that we will incorporate two parallel strategies into our data analysis: (1) a pragmatic health services-oriented approach, using an a priori analytical construct, the 'Timing it Right' framework and (2) a constructivist grounded theory approach which allows the emergence of new themes and theoretical understandings from the data. We will subsequently use Qualitative Health Needs Assessment methodology to inform the development of timely and responsive healthcare interventions throughout the recovery process.

ETHICS AND DISSEMINATION

The protocol has been approved by the Lothian Research Ethics Committee (protocol number HSRU011). The study has been added to the UK Clinical Research Network Database (study ID. 9986). The authors will disseminate the findings in peer reviewed publications and to relevant critical care stakeholder groups.

Cognitive functioning, mental health, and quality of life in ICU survivors: an overview

The significant and sometimes permanent effects of critical illness on wide-ranging aspects of functioning are increasingly recognized. Among the areas affected are acute and long-term cognitive functioning, depression, anxiety, PTSD, and quality of life. These and other areas are increasingly being studied and indeed are increasingly the focus of clinical attention and investigations. These conditions have been a focus of attention for more than a dozen years, with much improvement occurring in the ability to characterize these phenomena. For instance, in intervening years, it has been learned that cognitive impairment is highly prevalent and functionally disruptive and that it occurs in wide-ranging domains. Key questions remain unanswered with regard to vital questions such as determining causes, risk factors, and mechanisms as well as the degree to which brain injuries associated with critical illness are amenable to rehabilitation. Little remains known about the effects of critical illness on elderly ICU cohorts and on the neurologic functioning of individuals with preexisting impairment versus those who are normal. Few data exist regarding the development of strategies designed to prevent the emergence of neuropsychological deficits after critical illness. Although great progress has been made and is ongoing, a pressing need exists for additional investigation of cognitive impairment and other conditions,such as PTSD and quality of life after critical illness, that will seek to untangle the many pertinent questions related to this condition and that will ultimately offer help and hope to the thousands of survivors affected by this condition.

Is hypoglycaemia dangerous?

Tight glycaemic control (TGC) for patients treated in an intensive care unit ICU is associated with an increased risk for hypoglycaemia. Since hypoglycaemia mainly occurs in the sickest patients, no matter whether TGC is applied or not, it might be a marker for severity of illness or a harmful event in itself. Furthermore, it remains a matter of debate whether harmful effects of hypoglycaemia outbalance the clinical benefits of TGC. This review focusses on the clinical manifestations of hypoglycaemia in the critically ill and highlights its potential short- and long-term consequences specifically concerning neurocognitive function.

Acute respiratory distress syndrome, sepsis, and cognitive decline: a review and case study

The objective of this investigation is to review existing research pertaining to cognitive impairment and decline following critical illness and describe a case involving a 49-year-old female with sepsis and acute respiratory distress syndrome (ARDS) with no prior neurologic history who, compared to baseline neuropsychological test data, experienced dramatic cognitive decline and brain atrophy following treatment in the medical intensive care unit (ICU) at Vanderbilt University Medical Center. The patient participated in detailed clinical interviews and underwent comprehensive neuropsychological testing and neurological magnetic resonance imaging (MRI) at approximately 8 months and 3.5 years after ICU discharge. Compared to pre-ICU baseline test data, her intellectual function declined approximately 2 standard deviations from 139 to 106 (from the 99 to the 61 percentile) on a standardized intelligence test 8 months post-discharge, with little subsequent improvement. Initial diffusion tensor brain magnetic resonance imaging (DT-MRI) at the end of ICU hospitalization showed diffuse abnormal hyperintense areas involving predominately white matter in both hemispheres and the left cerebellum. A brain MRI nearly 4 years after ICU discharge demonstrated interval development of profound and generalized atrophy with sulcal widening and ventricular enlargement. The magnitude of cognitive decline experienced by ICU survivors is difficult to quantify due to the unavailability of pre-morbid neuropsychological data. The current case, conducted on a patient with baseline neuropsychological data, illustrates the trajectory of decline occurring after critical illness and ICU-associated brain injury with marked atrophy and concomitant cognitive impairments.

Cognitive functioning, mental health, and quality of life in ICU survivors: an overview

Critical illness can and often does lead to significant cognitive impairment and to the development of psychological disorders. These conditions are persistent and, although they improve with time, often fail to completely abate. Although the functional correlates of cognitive and psychological morbidity (depression, anxiety, and posttraumatic stress disorder) have been studied, they may include poor quality of life, inability to return to work or to work at previously established levels, and inability to function effectively in emotional and interpersonal domains. The potential etiologies of cognitive impairment and psychological morbidity in ICU survivors are particularly poorly understood and may vary widely across patients. Potential contributors may include the potentially toxic effects of sedatives and narcotics, delirium, hypoxia, glucose dysregulation, metabolic derangements, and inflammation. Patients with preexisting vulnerabilities, including predisposing genetic factors, and frail elderly populations may be at particular risk for emergence of acceleration of conditions such as mild cognitive impairment.

Cognitive dysfunction after critical illness: measurement, rehabilitation, and disclosure

A growing consensus seems to be emerging that neurocognitive outcomes are poor for patients who have been critically ill with acute respiratory distress syndrome and multiple organ failure. However, intensive care unit delirium, post-traumatic stress disorder, and other outcomes must be considered as potentially confounding factors. Once the uncertainty around the causes of postmorbid cognitive functioning is acknowledged, there are practical implications for appropriate rehabilitative interventions and there are ethical implications for the kinds of appropriate disclosure to patients.

Delirium and long-term cognitive impairment

Delirium is a severe, acute neuropsychiatric syndrome that is highly prevalent in acute hospital populations. Delirium has noticeable effects on length of hospitalization, cost of care, mortality and morbidity. In addition to these well-established adverse consequences, there is increasing evidence linking delirium and a higher risk of long-term cognitive impairment (LTCI), including dementia. A prior review (Jackson, Gordon, Hart, Hopkins, & Ely, 2004), in which nine studies (total N = 1,885, years 1989-2003) were considered, concluded that there was evidence for an association between delirium and LTCI. Here we provide a review of studies published since Jackson's review. We included nine reports, with a total of 2,025 patients. The studies show diverse sample sizes, methodologies, designs and patient populations. However, taken together, the results of these new studies broadly confirm that there is a link between delirium and LTCI. We go on to discuss putative mechanisms and explanations. These include (1) delirium as a marker of chronic progressive pathology, but unrelated to any progression, (2) delirium as a consequence of acute brain damage which is also responsible for a 'single hit' or triggering of active processes causing LTCI, (3) delirium itself as a cause of LTCI, and (4) drug treatment of delirium or other conditions as a cause of LTCI. We conclude with suggestions for future research.

Bench-to-bedside review: brain-lung interaction in the critically ill--a pending issue revisited

Brain and/or lung injury is the most frequent cause of admission to critical care units and patients in this setting frequently develop multiple organ dysfunction with high rates of morbidity and mortality. Mechanical ventilation is commonly used in the management of these critically ill patients and the consequent inflammatory response, together with other physiological factors, is also thought to be involved in distal organ dysfunction. This peripheral imbalance is based on a multiple-pathway cross-talk between the lungs and other organs, including the brain. Interestingly, acute respiratory distress syndrome survivors frequently present some cognitive deterioration at discharge. Such neurological dysfunction might be a secondary marker of injury and the neuroanatomical substrate for downstream impairment of other organs. Brain-lung interactions have received little attention in the literature, but recent evidence suggests that both the lungs and brain are promoters of inflammation through common mediators. This review addresses the current status of evidence regarding brain-lung interactions, their pathways and current interventions in critically ill patients receiving mechanical ventilation.

Cognitive dysfunction in intensive care survivors

Cognitive dysfunction is increasingly recognized as a common, often prolonged and potentially disabling complication of critical illness. While demonstrable in patients who have survived a variety of both medical and surgical conditions, its causes remain unclear. Screening of patients in intensive care units and at follow up may help identify those who could benefit from cognitive rehabilitation.

Cognitive sequelae in acute respiratory distress syndrome patients with and without recall of the intensive care unit

Some critically ill patients have dramatic recollections of the intensive care unit (ICU), whereas 23-50% have little or no recollection of their ICU stay. In addition, cognitive impairments are common following critical illness and ICU treatment. Little is known regarding the relationship between cognitive sequelae and ICU recall. We assessed recall of the ICU and its relationship to cognitive functioning at hospital discharge and 1 and 2 years after discharge in 70 consecutive acute respiratory distress syndrome (ARDS) patients. Seventeen patients (24%) had no recall of the ICU. Patients without ICU recall had increased rates of cognitive sequelae at hospital discharge and 1-year follow-up compared with the ICU recall group. Patients without ICU recall had a greater magnitude of cognitive impairments at hospital discharge, but not at 1- or 2-year follow-up. Profile analysis showed significant group differences in general intellectual functioning, executive function, processing speed, and spatial skills at hospital discharge, but not at 1- or 2-year follow-up. Estimated premorbid intelligence scores were inversely related to the magnitude of cognitive sequelae, suggesting greater "cognitive reserve" in patients with fewer cognitive decrements.

Post-traumatic stress disorder and post-traumatic stress symptoms following critical illness in medical intensive care unit patients: assessing the magnitude of the problem

Introduction

Post-traumatic stress disorder (PTSD) is a potentially serious psychiatric disorder that has traditionally been associated with traumatic stressors such as participation in combat, violent assault, and survival of natural disasters. Recently, investigators have reported that the experience of critical illness can also lead to PTSD, although details of the association between critical illness and PTSD remain unclear.

Methods

We conducted keyword searches of MEDLINE and Psych Info and investigations of secondary references for all articles pertaining to PTSD in medical intensive care unit (ICU) survivors.

Results

From 78 screened papers, 16 studies (representing 15 cohorts) and approximately 920 medical ICU patients met inclusion criteria. A total of 10 investigations used brief PTSD screening tools exclusively as opposed to more comprehensive diagnostic methods. Reported PTSD prevalence rates varied from 5% to 63%, with the three highest prevalence estimates occurring in studies with fewer than 30 patients. Loss to follow-up rates ranged from 10% to 70%, with average loss to follow-up rates exceeding 30%.

Conclusion

Exact PTSD prevalence rates cannot be determined due to methodological limitations such as selection bias, loss to follow-up, and the wide use of screening (as opposed to diagnostic) instruments. In general, the high prevalence rates reported in the literature are likely to be overestimates due to the limitations of the investigations conducted to date. Although PTSD may be a serious problem in some survivors of critical illness, data on the whole population are inconclusive. Because the magnitude of the problem posed by PTSD in survivors of critical illness is unknown, there remains a pressing need for larger and more methodologically rigorous investigations of PTSD in ICU survivors.

Bench-to-bedside review: critical illness-associated cognitive dysfunction--mechanisms, markers, and emerging therapeutics

Cognitive dysfunction is common in critically ill patients, not only during the acute illness but also long after its resolution. A large number of pathophysiologic mechanisms are thought to underlie critical illness-associated cognitive dysfunction, including neuro-transmitter abnormalities and occult diffuse brain injury. Markers that could be used to evaluate the influence of specific mechanisms in individual patients include serum anticholinergic activity, certain brain proteins, and tissue sodium concentration determination via high-resolution three-dimensional magnetic resonance imaging. Although recent therapeutic advances in this area are exciting, they are still too immature to influence patient care. Additional research is needed if we are to understand better the relative contributions of specific mechanisms to the development of critical illness-associated cognitive dysfunction and to determine whether these mechanisms might be amenable to treatment or prevention.

Delirium and cognitive dysfunction in the intensive care unit

Delirium is an under-recognized, highly prevalent form of organ dysfunction in the intensive care unit (ICU). It is imperative to be aware of risk factors for delirium in the ICU, some of which are modifiable. In the last 5 years, a new tool for detecting delirium among critically ill patients has been validated and found reliable for use at the bedside by psychiatrists and nonpsychiatrically trained personnel as well. The tool, the Confusion Assessment Method for the Intensive Care Unit, has enabled determination of the serious sequelae of delirium, including increased mortality, higher cost, longer length of hospital stay, failure of extubation, and burdensome, long-term cognitive impairment. This article reviews prevention and treatment options, and current pharmacologic and nonpharmacologic approaches to delirium, acknowledging limited but improving quality of evidence to date.

Clinical review: beyond immediate survival from resuscitation-long-term outcome considerations after cardiac arrest

A substantial body of literature concerning resuscitation from cardiac arrest now exists. However, not surprisingly, the greater part concerns the cardiac arrest event itself and optimising survival and outcome at relatively proximal time points. The aim of this review is to present the evidence base for interventions and therapeutic strategies that might be offered to patients surviving the immediate aftermath of a cardiac arrest, excluding components of resuscitation itself that may lead to benefits in long-term survival. In addition, this paper reviews the data on long-term impact, physical and neuropsychological, on patients and their families, revealing a burden that is often underestimated and underappreciated. As greater numbers of patients survive cardiac arrest, outcome measures more sophisticated than simple survival are required.