The cognitive consequences of critical illness: practical recommendations for screening and assessment

Intensive Care Admission and Early Neuro-Rehabilitation. Lessons for COVID-19?

Coronavirus disease 2019 (COVID-19) requires admission to intensive care (ICU) for the management of acute respiratory distress syndrome in about 5% of cases. Although our understanding of COVID-19 is still incomplete, a growing body of evidence is indicating potential direct deleterious effects on the central and peripheral nervous systems. Indeed, complex and long-lasting physical, cognitive, and functional impairments have often been observed after COVID-19. Early (defined as during and immediately after ICU discharge) rehabilitative interventions are fundamental for reducing the neurological burden of a disease that already heavily affects lung function with pulmonary fibrosis as a possible long-term consequence. In addition, ameliorating neuromuscular weakness with early rehabilitation would improve the efficiency of respiratory function as respiratory muscle atrophy worsens lung capacity. This review briefly summarizes the polymorphic burden of COVID-19 and addresses possible early interventions that could minimize the neurological and systemic impact. In fact, the benefits of early multidisciplinary rehabilitation after an ICU stay have been shown to be advantageous in several clinical conditions making an early rehabilitative approach generalizable and desirable to physicians from a wide range of different specialties.

Individual Differences in Self-Talk Frequency: Social Isolation and Cognitive Disruption

Despite the popularity of research on intrapersonal communication across many disciplines, there has been little attention devoted to the factors that might account for individual differences in talking to oneself. In this paper, I explore two possible explanations for why people might differ in the frequency of their self-talk. According to the “social isolation” hypothesis, spending more time alone or having socially isolating experiences will be associated with increased self-talk. According to the “cognitive disruption” hypothesis, having self-related experiences that are cognitively disruptive will be associated with increased self-talk frequency. Several studies using the Self-Talk Scale are pertinent to these hypotheses. The results indicate good support for the social isolation hypothesis and strong support for the cognitive disruption hypothesis. I conclude the paper with a wide range of implications for future research on individual differences in self-talk and other kinds of intrapersonal communication.

Prolonged Treatment with Propofol Transiently Impairs Proliferation but Not Survival of Rat Neural Progenitor Cells In Vitro

Neurocognitive dysfunction is common in survivors of intensive care. Prolonged sedation has been implicated but the mechanisms are unclear. Neurogenesis continues into adulthood and is implicated in learning. The neural progenitor cells (NPC) that drive neurogenesis have receptors for the major classes of sedatives used clinically, suggesting that interruption of neurogenesis may partly contribute to cognitive decline in ICU survivors. Using an in vitro system, we tested the hypothesis that prolonged exposure to propofol concentration- and duration-dependently kills or markedly decreases the proliferation of NPCs. NPCs isolated from embryonic day 14 Sprague-Dawley rat pups were exposed to 0, 2.5, or 5.0 μg/mL of propofol, concentrations consistent with deep clinical anesthesia, for either 4 or 24 hours. Cells were assayed for cell death and proliferation either immediately following propofol exposure or 24 hours later. NPC death and apoptosis were measured by propidium iodine staining and cleaved caspase-3 immunocytochemistry, respectively, while proliferation was measured by EdU incorporation. Staurosporine (1μM for 6h) was used as a positive control for cell death. Cells were analyzed with unbiased high-throughput immunocytochemistry. There was no cell death at either concentration of propofol or duration of exposure. Neither concentration of propofol impaired NPC proliferation when exposure lasted 4 h, but when exposure lasted 24 h, propofol had an anti-proliferative effect at both concentrations (P < 0.0001, propofol vs. control). However, this effect was transient; proliferation returned to baseline 24 h after discontinuation of propofol (P = 0.37, propofol vs. control). The transient but reversible suppression of NPC proliferation, absence of cytotoxicity, and negligible effect on the neural stem cell pool pool suggest that propofol, even in concentrations used for clinical anesthesia, has limited impact on neural progenitor cell biology.

Neuropathogenesis of delirium: review of current etiologic theories and common pathways

Delirium is a neurobehavioral syndrome caused by dysregulation of neuronal activity secondary to systemic disturbances. Over time, a number of theories have been proposed in an attempt to explain the processes leading to the development of delirium. Each proposed theory has focused on a specific mechanism or pathologic process (e.g., dopamine excess or acetylcholine deficiency theories), observational and experiential evidence (e.g., sleep deprivation, aging), or empirical data (e.g., specific pharmacologic agents' association with postoperative delirium, intraoperative hypoxia). This article represents a review of published literature and summarizes the top seven proposed theories and their interrelation. This review includes the "neuroinflammatory," "neuronal aging," "oxidative stress," "neurotransmitter deficiency," "neuroendocrine," "diurnal dysregulation," and "network disconnectivity" hypotheses. Most of these theories are complementary, rather than competing, with many areas of intersection and reciprocal influence. The literature suggests that many factors or mechanisms included in these theories lead to a final common outcome associated with an alteration in neurotransmitter synthesis, function, and/or availability that mediates the complex behavioral and cognitive changes observed in delirium. In general, the most commonly described neurotransmitter changes associated with delirium include deficiencies in acetylcholine and/or melatonin availability; excess in dopamine, norepinephrine, and/or glutamate release; and variable alterations (e.g., either a decreased or increased activity, depending on delirium presentation and cause) in serotonin, histamine, and/or γ-aminobutyric acid. In the end, it is unlikely that any one of these theories is fully capable of explaining the etiology or phenomenologic manifestations of delirium but rather that two or more of these, if not all, act together to lead to the biochemical derangement and, ultimately, to the complex cognitive and behavioral changes characteristic of delirium.

[Lung-brain interaction in the mechanically ventilated patient]

Patients with acute lung injury or acute respiratory distress syndrome (ARDS) admitted to the ICU present neuropsychological alterations, which in most cases extend beyond the acute phase and have an important adverse effect upon quality of life. The aim of this review is to deepen in the analysis of the complex interaction between lung and brain in critically ill patients subjected to mechanical ventilation. This update first describes the neuropsychological alterations occurring both during the acute phase of ICU stay and at discharge, followed by an analysis of lung-brain interactions during mechanical ventilation, and finally explores the etiology and mechanisms leading to the neurological disorders observed in these patients. The management of critical patients requires an integral approach focused on minimizing the deleterious effects over the short, middle or long term.

[Lung-brain interaction in the mechanically ventilated patient]

Patients with acute lung injury or acute respiratory distress syndrome (ARDS) admitted to the ICU present neuropsychological alterations, which in most cases extend beyond the acute phase and have an important adverse effect upon quality of life. The aim of this review is to deepen in the analysis of the complex interaction between lung and brain in critically ill patients subjected to mechanical ventilation. This update first describes the neuropsychological alterations occurring both during the acute phase of ICU stay and at discharge, followed by an analysis of lung-brain interactions during mechanical ventilation, and finally explores the etiology and mechanisms leading to the neurological disorders observed in these patients. The management of critical patients requires an integral approach focused on minimizing the deleterious effects over the short, middle or long term.

The association between brain volumes, delirium duration, and cognitive outcomes in intensive care unit survivors: the VISIONS cohort magnetic resonance imaging study*

OBJECTIVE

Delirium duration is predictive of long-term cognitive impairment in intensive care unit survivors. Hypothesizing that a neuroanatomical basis may exist for the relationship between delirium and long-term cognitive impairment, we conducted this exploratory investigation of the associations between delirium duration, brain volumes, and long-term cognitive impairment.

DESIGN, SETTING, AND PATIENTS

A prospective cohort of medical and surgical intensive care unit survivors with respiratory failure or shock.

MEASUREMENTS

Quantitative high resolution 3-Tesla brain magnetic resonance imaging was used to calculate brain volumes at discharge and 3-month follow-up. Delirium was evaluated using the confusion assessment method for the intensive care unit; cognitive outcomes were tested at 3- and 12-month follow-up. Linear regression was used to examine associations between delirium duration and brain volumes, and between brain volumes and cognitive outcomes.

RESULTS

A total of 47 patients completed the magnetic resonance imaging protocol. Patients with longer duration of delirium displayed greater brain atrophy as measured by a larger ventricle-to-brain ratio at hospital discharge (0.76, 95% confidence intervals [0.10, 1.41]; p = .03) and at 3-month follow-up (0.62 [0.02, 1.21], p = .05). Longer duration of delirium was associated with smaller superior frontal lobe (-2.11 cm(3) [-3.89, -0.32]; p = .03) and hippocampal volumes at discharge (-0.58 cm(3) [-0.85, -0.31], p < .001)--regions responsible for executive functioning and memory, respectively. Greater brain atrophy (higher ventricle-to-brain ratio) at 3 months was associated with worse cognitive performances at 12 months (lower Repeatable Battery for the Assessment of Neuropsychological Status score -11.17 [-21.12, -1.22], p = .04). Smaller superior frontal lobes, thalamus, and cerebellar volumes at 3 months were associated with worse executive functioning and visual attention at 12 months.

CONCLUSIONS

These preliminary data show that longer duration of delirium is associated with smaller brain volumes up to 3 months after discharge, and that smaller brain volumes are associated with long-term cognitive impairment up to 12 months. We cannot, however, rule out that smaller preexisting brain volumes explain these findings.

The relationship between delirium duration, white matter integrity, and cognitive impairment in intensive care unit survivors as determined by diffusion tensor imaging: the VISIONS prospective cohort magnetic resonance imaging study*

OBJECTIVE

Evidence is emerging that delirium duration is a predictor of long-term cognitive impairment in intensive care unit survivors. Relationships between 1) delirium duration and brain white matter integrity, and 2) white matter integrity and long-term cognitive impairment are poorly understood and could be explored using magnetic resonance imaging.

DESIGN, SETTING, PATIENTS

A two-center, prospective cohort study incorporating delirium monitoring, neuroimaging, and cognitive testing in intensive care unit survivors.

MEASUREMENTS

Delirium was evaluated with the Confusion Assessment Method for the Intensive Care Unit and cognitive outcomes were tested at 3 and 12-month follow-up. Following the intensive care unit stay, fractional anisotropy, a measure of white matter integrity, was calculated quantitatively using diffusion tensor imaging with a 3-T magnetic resonance imaging scanner at hospital discharge and 3-month follow-up. We examined associations between 1) delirium duration and fractional anisotropy and 2) fractional anisotropy and cognitive outcomes using linear regression adjusted for age and sepsis.

RESULTS

A total of 47 patients with a median age of 50 yrs completed the diffusion tensor imaging-magnetic resonance imaging protocol. Greater duration of delirium (3 vs. 0 days) was associated with lower fractional anisotropy (i.e., reduced fractional anisotropy = white matter disruption) in the genu (-0.02; p = .04) and splenium (-0.01; p = .02) of the corpus callosum and anterior limb of the internal capsule (-0.02; p =.01) at hospital discharge. These associations persisted at 3 months for the genu (-0.02; p =.02) and splenium (-0.01; p = .004). Lower fractional anisotropy in the anterior limb of internal capsule at discharge and in genu of corpus callosum at three months was associated with worse cognitive scores at 3 and 12 months.

CONCLUSIONS

In this pilot investigation, delirium duration in the intensive care unit was associated with white matter disruption at both discharge and 3 months. Similarly, white matter disruption was associated with worse cognitive scores up to 12 months later. This hypothesis-generating investigation may help design future studies to explore these complex relationships in greater depth.

Delirium: an emerging frontier in the management of critically ill children

Delirium is a syndrome of acute brain dysfunction that commonly occurs in critically ill adults and most certainly is prevalent in critically ill children all over the world. The dearth of information about the incidence, prevalence, and severity of pediatric delirium stems from the simple fact that there have not been well-validated instruments for routine delirium diagnosis at the bedside. This article reviewed the emerging solutions to this problem, including description of a new pediatric tool called the pCAM-ICU. In adults, delirium is responsible for significant increases in both morbidity and mortality in critically ill patients. The advent of new tools for use in critically ill children will allow the epidemiology of this form of acute brain dysfunction to be studied adequately, will allow clinical management algorithms to be developed and implemented following testing, and will present the necessary incorporation of delirium as an outcome measure for future clinical trials in pediatric critical care medicine.

Survivors of septic shock caused by Neisseria meningitidis in childhood: psychosocial outcomes in young adulthood

OBJECTIVE

To investigate long-term psychosocial outcomes in young adults who survived septic shock caused by Neisseria meningitidis (meningococcal septic shock) during childhood.

DESIGN

A cross-sectional study.

SETTING

The psychological investigation took place in the department of Child and Adolescent Psychiatry of the Erasmus MC-Sophia Children's Hospital.

PATIENTS

All consecutive surviving patients with meningococcal septic shock requiring intensive care treatment at the pediatric intensive care unit between 1988 and 2001.

INTERVENTION

To explore biographical characteristics (such as living conditions, educational, occupational, and marital status) and illness-related physical or social consequences a structured interview was used. To assess intellectual functioning the Groninger Intelligence Test 2 was used and to assess behavioral/emotional problems, the Adult Self-Report was used.

MEASUREMENTS AND MAIN RESULTS

Fifty-eight of 83 eligible septic shock survivors were evaluated (response rate: 70%). The patients were 16-31 yrs old at time of follow-up (median age: 21 yrs old). These patients had had meningococcal septic shock before 18 yrs of age. Median follow-up interval was 13 yrs, with a range of 4 to 16 yrs. For the vast majority of meningococcal septic shock patients, outcomes on biographical characteristics, intellectual functioning, and levels of behavioral/emotional problems were comparable to those of reference groups. A minority (5% to 20%) still report illness-related physical or social consequences, behavioral and emotional problems, and lower intellectual functioning.

CONCLUSIONS

Despite favorable outcomes for the majority of meningococcal septic shock patients in the long term, an important minority (5% to 20%) still struggles with ongoing problems as to behavioral/emotional problems, intellectual functioning, biographical characteristics, and illness-related physical or social consequences.

Improving delirium care in the intensive care unit: the design of a pragmatic study

BACKGROUND

Delirium prevalence in the intensive care unit (ICU) is high. Numerous psychotropic agents are used to manage delirium in the ICU with limited data regarding their efficacy or harms.

METHODS/DESIGN

This is a randomized controlled trial of 428 patients aged 18 and older suffering from delirium and admitted to the ICU of Wishard Memorial Hospital in Indianapolis. Subjects assigned to the intervention group will receive a multicomponent pharmacological management protocol for delirium (PMD) and those assigned to the control group will receive no change in their usual ICU care. The primary outcomes of the trial are (1) delirium severity as measured by the Delirium Rating Scale revised-98 (DRS-R-98) and (2) delirium duration as determined by the Confusion Assessment Method for the ICU (CAM-ICU). The PMD protocol targets the three neurotransmitter systems thought to be compromised in delirious patients: dopamine, acetylcholine, and gamma-aminobutyric acid. The PMD protocol will target the reduction of anticholinergic medications and benzodiazepines, and introduce a low-dose of haloperidol at 0.5-1 mg for 7 days. The protocol will be delivered by a combination of computer (artificial intelligence) and pharmacist (human intelligence) decision support system to increase adherence to the PMD protocol.

DISCUSSION

The proposed study will evaluate the content and the delivery process of a multicomponent pharmacological management program for delirium in the ICU.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00842608.

Compromised autonomy and the seriously ill patient

Respect for patient autonomy has become the preeminent principle of medical ethics, to the point that tools have been developed, such as instructive directives, in an attempt to preserve a semblance of autonomy even when it has become clearly and irretrievably lost. Much of the practice around the respect for autonomy, however, mistakenly supposes that the capacity for autonomous choice is an all-or-nothing proposition. But seriously ill patients may retain some ability to participate in discussions of medical care yet have their autonomy profoundly compromised by physical duress, cognitive dysfunction, or delirium. The choices of individuals with compromised autonomy do not carry the same moral weight as those of the fully autonomous. Clinicians, therefore, cannot rely on such choices for guiding medical decisions and are obligated to evaluate them more fully before acting. We argue that clinicians should compare the choices of individuals with compromised autonomy to a medical assessment of the patient's best interest. When the patient's choice and the best-interests assessment are discordant, acting in the patient's best interest may, at times, rightly override the requests of the patient. Such an approach, under a tightly constrained set of circumstances, would permit both the provision and the withholding of medical interventions despite patient requests to the contrary.

Hypoglycemia aggravates critical illness-induced neurocognitive dysfunction

OBJECTIVE Tight glycemic control (TGC) in critically ill patients is associated with an increased risk of hypoglycemia. Whether those short episodes of hypoglycemia are associated with adverse morbidity and mortality is a matter of discussion. Using a case-control study design, we investigated whether hypoglycemia under TGC causes permanent neurocognitive dysfunction in patients surviving critical illness. RESEARCH DESIGN AND METHODS From our patient data management system, we identified adult survivors treated for >72 h in our surgical intensive care unit (ICU) between 2004 and 2007 (n = 4,635) without a history of neurocognitive dysfunction or structural brain abnormalities who experienced at least one episode of hypoglycemia during treatment (hypo group) (n = 37). For each hypo group patient, one patient stringently matched for demographic- and disease-related data were identified as a control subject. We performed a battery of neuropsychological tests investigating five areas of cognitive functioning in both groups at least 1 year after ICU discharge. Test results were compared with data from healthy control subjects and between groups. RESULTS Critical illness caused neurocognitive dysfunction in all tested domains in both groups. The dysfunction was aggravated in hypo group patients in one domain, namely that of visuospatial skills (P < 0.01). Besides hypoglycemia, both hyperglycemia (r = -0.322; P = 0.005) and fluctuations of blood glucose (r = -0.309; P = 0.008) were associated with worse test results in this domain. CONCLUSIONS Hypoglycemia was found to aggravate critical illness-induced neurocognitive dysfunction to a limited, but significant, extent; however, an impact of hyperglycemia and fluctuations of blood glucose on neurocognitive function cannot be excluded.

Delirium: an emerging frontier in the management of critically ill children

The objectives of this article are (1) to introduce pediatric delirium and provide understanding of acute brain dysfunction with its classification and clinical presentations (2) to understand how delirium is diagnosed and discuss current modes of delirium diagnosis in the critically ill adult population and translation to pediatrics (3) to understand the prevalence and prognostic significance of delirium in the adult and pediatric critically ill population (4) to discuss the pathophysiology of delirium as currently understood, and (5) to provide general management guidelines for delirium.

Pathophysiology of delirium in the intensive care unit

Delirium, or acute brain dysfunction, is a life-threatening global disturbance in cognitive functioning that frequently manifests in critically ill patients. This review examines the current status of knowledge regarding the pathophysiology of delirium in the ICU, in particular, evaluating the role of iatrogenic factors such as sedatives and analgesic administration in brain dysfunction. This hypothesis is considered along with several other plausible mechanisms of ICU delirium, including sepsis, postoperative cognitive dysfunction, and changes in biomarkers and neurotransmitters. The review concludes by highlighting potential future directions in molecular genetics for the elucidation of delirium and its long-term consequences.