Sleep and circadian rhythm disturbances in intensive care unit (ICU)-acquired delirium: a case-control study

Mechanisms underlying delirium in patients with critical illness

Delirium is an acute, global cognitive disorder syndrome, also known as acute brain syndrome, characterized by disturbance of attention and awareness and fluctuation of symptoms. Its incidence is high among critically ill patients. Once patients develop delirium, it increases the risk of unplanned extubation, prolongs hospital stay, increases the risk of nosocomial infection, post-intensive care syndrome-cognitive impairment, and even death. Therefore, it is of great importance to understand how delirium occurs and to reduce the incidence of delirium in critically ill patients. This paper reviews the potential pathophysiological mechanisms of delirium in critically ill patients, with the aim of better understanding its pathophysiological processes, guiding the formulation of effective prevention and treatment strategies, providing a basis for clinical medication.

Development and Validation of Machine Learning Models to Predict Postoperative Delirium Using Clinical Features and Polysomnography Variables

Background: Delirium affects up to 50% of patients following high-risk surgeries and is associated with poor long-term prognosis. This study employed machine learning to predict delirium using polysomnography (PSG) and sleep-disorder questionnaire data, and aimed to identify key sleep-related factors for improved interventions and patient outcomes. Methods: We studied 912 adults who underwent surgery under general anesthesia at a tertiary hospital (2013-2024) and had PSG within 5 years of surgery. Delirium was assessed via clinical diagnoses, antipsychotic prescriptions, and psychiatric consultations within 14 days postoperatively. Sleep-related data were collected using PSG and questionnaires. Machine learning predictions were performed to identify postoperative delirium, focusing on model accuracy and feature importance. Results: This study divided the 912 patients into an internal training set (700) and an external test set (212). Univariate analysis identified significant delirium risk factors: midazolam use, prolonged surgery duration, and hypoalbuminemia. Sleep-related variables such as fewer rapid eye movement (REM) episodes and higher daytime sleepiness were also linked to delirium. An extreme gradient-boosting-based classification task achieved an AUC of 0.81 with clinical variables, 0.60 with PSG data alone, and 0.84 with both, demonstrating the added value of PSG data. Analysis of Shapley additive explanations values highlighted important predictors: surgery duration, age, midazolam use, PSG-derived oxygen saturation nadir, periodic limb movement index, and REM episodes, demonstrating the relationship between sleep patterns and the risk of delirium. Conclusions: The artificial intelligence model integrates clinical and sleep variables and reliably identifies postoperative delirium, demonstrating that sleep-related factors contribute to its identification. Predicting patients at high risk of developing postoperative delirium and closely monitoring them could reduce the costs and complications associated with delirium.

The Bispectral Electroencephalography Method Quantifies Postoperative Delirium-Like States in Young and Aged Male Mice After Head-Mount Implantation Surgery

Delirium, a syndrome characterized by an acute change in attention, awareness, and cognition, is commonly observed in older adults, although there are few quantitative monitoring methods in the clinical setting. We developed a bispectral electroencephalography (BSEEG) method capable of detecting delirium and can quantify the severity of delirium using a novel algorithm. Preclinical application of this novel BSEEG method can capture a delirium-like state in mice following lipopolysaccharide administration. However, its application to postoperative delirium (POD) has not yet been validated in animal experiments. This study aimed to create a POD model in mice with the BSEEG method by monitoring BSEEG scores following EEG head-mount implantation surgery and throughout the recovery. We compared the BSEEG scores of C57BL/6J young (2-3 months old) with aged (18-19 months old) male mice for quantitative evaluation of POD-like states. Postoperatively, both groups displayed increased BSEEG scores and a loss of regular diurnal changes in BSEEG scores. In young mice, BSEEG scores and regular diurnal changes recovered relatively quickly to baseline by postoperative day (PO-Day) 3. Conversely, aged mice exhibited prolonged increases in postoperative BSEEG scores and it reached steady states only after PO-Day 8. This study suggests that the BSEEG method can be utilized as a quantitative measure of POD and assess the effect of aging on recovery from POD in the preclinical model.

The influence of sleep disorders on perioperative neurocognitive disorders among the elderly: A narrative review

This review comprehensively assesses the epidemiology, interaction, and impact on patient outcomes of perioperative sleep disorders (SD) and perioperative neurocognitive disorders (PND) in the elderly. The incidence of SD and PND during the perioperative period in older adults is alarmingly high, with SD significantly contributing to the occurrence of postoperative delirium. However, the clinical evidence linking SD to PND remains insufficient, despite substantial preclinical data. Therefore, this study focuses on the underlying mechanisms between SD and PND, underscoring that potential mechanisms driving SD-induced PND include uncontrolled central nervous inflammation, blood-brain barrier disruption, circadian rhythm disturbances, glial cell dysfunction, neuronal and synaptic abnormalities, impaired central metabolic waste clearance, gut microbiome dysbiosis, hippocampal oxidative stress, and altered brain network connectivity. Additionally, the review also evaluates the effectiveness of various sleep interventions, both pharmacological and nonpharmacological, in mitigating PND. Strategies such as earplugs, eye masks, restoring circadian rhythms, physical exercise, noninvasive brain stimulation, dexmedetomidine, and melatonin receptor agonists have shown efficacy in reducing PND incidence. The impact of other sleep-improvement drugs (e.g., orexin receptor antagonists) and methods (e.g., cognitive-behavioral therapy for insomnia) on PND is still unclear. However, certain drugs used for treating SD (e.g., antidepressants and first-generation antihistamines) may potentially aggravate PND. By providing valuable insights and references, this review aimed to enhance the understanding and management of PND in older adults based on SD.

Effects of Chinese traditional five-element music intervention on postoperative delirium and sleep quality in elderly patients after non-cardiac surgery: a randomized controlled trial

BACKGROUND

Postoperative delirium (POD) is a common neurologic disorder among elderly patients after non-cardiac surgery, which leads to various negative outcomes. Sleep disorder is considered an important cause of POD. The objective of this study was to investigate whether the Chinese traditional five-element music intervention could reduce POD by improving sleep quality in elderly patients undergoing non-cardiac surgery.

METHODS

A total of 132 patients aged 65 to 90 years who underwent non-cardiac surgery were randomized to two groups: the intervention (n = 60) and the control group (n = 63). Patients in the intervention group were subjected to the Chinese traditional five-element music intervention during the perioperative, while patients in the control group had no music intervention. POD was evaluated using the Confusion Assessment Method (CAM) in the first 5 days after surgery. The Richards‒Campbell Sleep Questionnaire (RCSQ) was used to assess subjective sleep quality. The levels of nocturnal melatonin and cortisol in saliva were measured on the preoperative and the first 2 postoperative days.

RESULTS

The incidence of POD within 5 days was 27.0% in the control group and 11.7% in the intervention group. Preoperative PSQI and MMSE scores were associated with POD. The RCSQ scores on the first postoperative day were significantly decreased in the two groups compared to the preoperative day. Compared to the control group, the RCSQ scores showed a significant improvement in the intervention group on the first postoperative day. Compared to the control group, the level of saliva melatonin in the intervention group showed a significant increase on the first postoperative day. However, there was no statistical difference in cortisol levels between the two groups.

CONCLUSIONS

Chinese traditional five-element music intervention decreased the incidence of POD in elderly patients who underwent noncardiac surgery via improving sleep quality, which may be associated with increased levels of melatonin.

Feasibility and Acceptability of Using Wireless Limited Polysomnography to Capture Sleep Before, During, and After Hospitalization for Patients With Planned Cardiothoracic Surgery

BACKGROUND

Sleep disruption, a common symptom among patients requiring cardiovascular surgery, is a potential risk factor for the development of postoperative delirium. Postoperative delirium is a disorder of acute disturbances in cognition associated with prolonged hospitalization, cognitive decline, and mortality.

OBJECTIVE

The aim of this study was to evaluate the feasibility and acceptability of using polysomnography (PSG) to capture sleep in patients with scheduled cardiothoracic surgery.

METHODS

Wireless limited PSG assessed sleep at baseline (presurgery at home), postoperatively in the intensive care unit, and at home post hospital discharge. Primary outcomes were quality and completeness of PSG signals, and acceptability by participants and nursing staff.

RESULTS

Among 15 patients, PSG data were of high quality, and mean percentage of unscorable data was 5.5% ± 11.1%, 3.7% ± 5.4%, and 3.7% ± 8.4% for baseline, intensive care unit, and posthospitalization measurements, respectively. Nurses and patients found the PSG monitor acceptable.

CONCLUSIONS

Wireless, limited PSG to capture sleep across the surgical continuum was feasible, and data were of high quality. Authors of future studies will evaluate associations of sleep indices and development of postoperative delirium in this high-risk population.

Preoperative slow-wave sleep is associated with postoperative delirium after heart valve surgery: A prospective pilot study

Postoperative delirium (POD) is a very common neurological complication after valve surgery. Some studies have shown that preoperative sleep disorder is associated with POD, but the correlation between preoperative slow wave sleep (SWS) and POD remains unclear. Therefore, this study aims to identify the correlation between preoperative slow wave sleep and postoperative delirium in patients with heart valve disease. This was a prospective, observational study of elective valve surgery patients admitted to the Heart Medical Center between November 2021 and July 2022. Polysomnography (PSG) was used to monitor sleep architecture from 9:30 p.m. for 1 night before surgery to 6:30 a.m. on the day of surgery. Patients were assessed for postoperative delirium from postoperative day 1 to extubation or day 5 by using the Richmond Agitation/Sedation Scale (RASS) and the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). A total of 60 elective valve surgery patients were enrolled in this study. Prolonged N1 (11.44%) and N2 (58.62%) sleep, decreased N3 sleep (8.75%) and REM sleep (18.24%) within normal limits were the overall sleep architecture. Compared with patients without POD, patients with POD had less slow wave sleep 1 night before surgery (5.77% vs 10.88%, p < 0.001). After adjusting for confounding factors, slow wave sleep (OR: 0.647, 95% CI 0.493-0.851, p = 0.002) was found to be a protective factor for postoperative delirium. The preoperative SWS is a predictive factor of the POD in patients undergoing valve surgery. But further studies with larger sample sizes are still needed to elucidate the relationship between preoperative slow wave sleep and postoperative delirium.

Sleep and critical illness: a review

Critical illness and stays in the Intensive Care Unit (ICU) have significant impact on sleep. Poor sleep is common in this setting, can persist beyond acute critical illness, and is associated with increased morbidity and mortality. In the past 5 years, intensive care clinical practice guidelines have directed more focus on sleep and circadian disruption, spurring new initiatives to study and improve sleep complications in the critically ill. The global SARS-COV-2 (COVID-19) pandemic and dramatic spikes in patients requiring ICU level care also brought augmented levels of sleep disruption, the understanding of which continues to evolve. This review aims to summarize existing literature on sleep and critical illness and briefly discuss future directions in the field.

Steroids Provide Temporary Improvement of Refractory Pain Following Subarachnoid Hemorrhage

Introduction

Evidence for optimal analgesia following subarachnoid hemorrhage (SAH) is limited. Steroid therapy for pain refractory to standard regimens is common despite lack of evidence for its efficacy. We sought to determine if steroids reduced pain or utilization of other analgesics when given for refractory headache following SAH.

Methods

We performed a retrospective within-subjects cohort study of SAH patients who received steroids for refractory headache. We compared daily pain scores, total daily opioid, and acetaminophen doses before, during, and after steroids. Repeated measures were analyzed with a multivariable general linear model and generalized estimating equations.

Results

Included 52 patients treated with dexamethasone following SAH, of whom 11 received a second course, increasing total to 63 treatment epochs. Mean pain score on the first day of therapy was 7.92 (standard error of the mean [SEM] .37) and decreased to 6.68 (SEM .36) on the second day before quickly returning to baseline levels, 7.36 (SEM .33), following completion of treatment. Total daily analgesics mirrored this trend. Mean total opioid and acetaminophen doses on days one and two and two days after treatment were 47.83mg (SEM 6.22) and 1848mg (SEM 170.66), 34.24mg (SEM 5.12) and 1809mg (SEM 150.28), and 46.38mg (SEM 11.64) and 1833mg (SEM 174.23), respectively. Response to therapy was associated with older age, decreasing acetaminophen dosing, and longer duration of steroids. Hyperglycemia and sleep disturbance/delirium effected 28.6% and 55.6% of cases, respectively.

Conclusion

Steroid therapy for refractory pain in SAH patients may have modest, transient effects in select patients.

Circadian rhythm disturbance and delirium in ICU patients: a prospective cohort study

BACKGROUND

Patients treated in the intensive care unit (ICU) may experience a reversal of day and night. The circadian rhythm in ICU patients can be disturbed.

METHODS

To explore the relationship between ICU delirium and the circadian rhythms of melatonin, cortisol and sleep. A prospective cohort study was carried out in a surgical ICU of a tertiary teaching hospital. Patients who were conscious during the ICU stay after surgery and were scheduled to stay in the ICU for more than 24 h were enrolled. Serum melatonin and plasma cortisol levels were measured three times a day by drawing arterial blood on the first three days after ICU admission. Daily sleep quality was assessed by the Richard-Campbell Sleep Questionnaire (RCSQ). The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) was performed twice a day to screen for ICU delirium.

RESULTS

A total of 76 patients were included in this study, and 17 patients developed delirium during their ICU stay. Melatonin levels were different at 8:00 (p = 0.048) on day 1, at 3:00 (p = 0.002) and at 8:00 (p = 0.009) on day 2, and at all three time points on day 3 (p = 0.032, 0.014, 0.047) between delirium and non-delirium patients. The plasma cortisol level in the delirium patients was significantly lower than that in the non-delirium patients at 16:00 on day 1 (p = 0.025). The changes in melatonin and cortisol secretion levels exhibited obvious biological rhythmicity in non-delirium patients (p < 0.001 for melatonin, p = 0.026 for cortisol), while no rhythmicity was found in melatonin and cortisol secretion levels in the delirium group (p = 0.064 for melatonin, p = 0.454 for cortisol). There was no significant difference in RCSQ scores in the first three days between the two groups.

CONCLUSIONS

The disturbance of the circadian rhythm of melatonin and cortisol secretion was associated with the development of delirium in ICU patients. Clinical staff should pay more attention to the importance of maintaining patients' normal circadian rhythms in the ICU.

TRIAL REGISTRATION

The study was registered with the US National Institutes of Health ClinicalTrials.gov(NCT05342987) (25/04/2022).

Causes, Consequences, and Treatments of Sleep and Circadian Disruption in the ICU: An Official American Thoracic Society Research Statement

Background: Sleep and circadian disruption (SCD) is common and severe in the ICU. On the basis of rigorous evidence in non-ICU populations and emerging evidence in ICU populations, SCD is likely to have a profound negative impact on patient outcomes. Thus, it is urgent that we establish research priorities to advance understanding of ICU SCD. Methods: We convened a multidisciplinary group with relevant expertise to participate in an American Thoracic Society Workshop. Workshop objectives included identifying ICU SCD subtopics of interest, key knowledge gaps, and research priorities. Members attended remote sessions from March to November 2021. Recorded presentations were prepared and viewed by members before Workshop sessions. Workshop discussion focused on key gaps and related research priorities. The priorities listed herein were selected on the basis of rank as established by a series of anonymous surveys. Results: We identified the following research priorities: establish an ICU SCD definition, further develop rigorous and feasible ICU SCD measures, test associations between ICU SCD domains and outcomes, promote the inclusion of mechanistic and patient-centered outcomes within large clinical studies, leverage implementation science strategies to maximize intervention fidelity and sustainability, and collaborate among investigators to harmonize methods and promote multisite investigation. Conclusions: ICU SCD is a complex and compelling potential target for improving ICU outcomes. Given the influence on all other research priorities, further development of rigorous, feasible ICU SCD measurement is a key next step in advancing the field.

Sleep in the intensive care unit

PURPOSE OF REVIEW

Sleep is particularly important for critically ill patients. Here, we review the latest evidence on how sleep and circadian disruption in the intensive care unit (ICU) affects physiology and clinical outcomes, as well as the most recent advances in sleep and circadian rhythm promoting interventions including therapeutics.

RECENT FINDINGS

On a molecular level, clock genes dysrhythmia and altered immunity are clearly linked, particularly in sepsis. Melatonin may also be associated with insulin sensitivity in ICU patients. Clinically, changes in sleep architecture are associated with delirium, and sleep-promoting interventions in the form of multifaceted care bundles may reduce its incidence. Regarding medications, one recent randomized controlled trial (RCT) on melatonin showed no difference in sleep quality or incidence of delirium.

SUMMARY

Further investigation is needed to establish the clinical relevance of sleep and circadian disruption in the ICU. For interventions, standardized protocols of sleep promotion bundles require validation by larger multicenter trials. Administratively, such protocols should be individualized to both organizational and independent patient needs. Incorporating pharmacotherapy such as melatonin and nocturnal dexmedetomidine requires further evaluation in large RCTs.

An Automated Algorithm for Determining Sleep Using Single-Channel Electroencephalography to Detect Delirium: A Prospective Observational Study in Intensive Care Units

The relationship between polysomnography-based objective sleep and delirium in the intensive care unit (ICU) is inconsistent across studies, suggesting limitations in manually determining the sleep stage of critically ill patients. We objectively measured 24-h sleep using a single-channel electroencephalogram (SleepScope [SS]) and an under-mattress sleep monitor (Nemuri SCAN [NSCAN]), both of which have independent algorithms that automatically determine sleep and wakefulness. Eighteen patients (median age, 68 years) admitted to the ICU after valvular surgery or coronary artery bypass grafting were included, and their sleep time was measured one day after extubation. The median total sleep times (TSTs) measured by SS (TST-SS) and NSCAN were 548 (48−1050) and 1024 (462−1257) min, respectively. Two patients with delirium during the 24-h sleep measurement had very short TST-SS of 48 and 125 min, and the percentage of daytime sleep accounted for >80% in both SS and NSCAN. This preliminary case series showed marked sleep deprivation and increased rates of daytime sleeping in ICU patients with delirium. Although data accuracy from under-mattress sleep monitors is contentious, automated algorithmic sleep/wakefulness determination using a single-channel electroencephalogram may be useful in detecting delirium in ICU patients and could even be superior to polysomnography.

E4BP4 Coordinates Circadian Control of Cognition in Delirium

Improved understanding of the etiologies of delirium, a common and severe neuropsychiatric syndrome, would facilitate the disease prevention and treatment. Here, the authors invesitgate the role of circadian rhythms in the pathogenesis of delirium. They observe perturbance of circadian rhythms in mouse models of delirium and disrupted clock gene expression in patients with delirium. In turn, physiological and genetic circadian disruptions sensitize mice to delirium with aggravated cognitive impairment. Likewise, global deletion of E4bp4 (E4 promoter-binding protein), a clock gene markedly altered in delirium conditions, results in exacerbated delirium-associated cognitive decline. Cognitive decline in delirium models is attributed to microglial activation and impaired long-term potentiation in the hippocampus. Single-cell RNA-sequencing reveals microglia as the regulatory target of E4bp4. E4bp4 restrains microglial activation via inhibiting the ERK1/2 signaling pathway. Supporting this, mice lacking in microglial E4bp4 are delirious prone, whereas mice with E4bp4 specifically deleted in hippocampal CA1 neurons have a normal phenotype. Mechanistically, E4bp4 inhibits ERK1/2 signaling by trans-repressing Mapk1/3 (genes encoding ERK1/2) via direct binding to a D-box element in the promoter region. These findings define a causal role of clock dysfunction in delirium development and indicate E4bp4 as a regulator of cognition at the crosstalk between circadian clock and delirium.

Sleep assessment in critically ill adults: A systematic review and meta-analysis

PURPOSE

To systematically review sleep evaluation, characterize sleep disruption, and explore effects of sleepdisruption on outcomes in adult ICU patients.

MATERIALS AND METHODS

We systematically searched databases from May 1969 to June 2021 (PROSPERO protocol number: CRD42020175581). Prospective and retrospective studies were included studying sleep in critically ill adults, excluding patients with sleep or psychiatric disorders. Meta-regression methods were applied when feasible.

RESULTS

132 studies (8797 patients) were included. Fifteen sleep assessment methods were identified, with only two validated. Patients had significant sleep disruption, with low sleep time, and low proportion of restorative rapid eye movement (REM). Sedation was associated with higher sleep efficiency and sleep time. Surgical versus medical patients had lower sleep quality. Patients on ventilation had a higher amount of light sleep. Meta-regression only suggested an association between total sleep time and occurrence of delirium (p < 0.001, 15 studies, 519 patients). Scarce data precluded further analyses. Sleep characterized with polysomnography (PSG) correlated well with actigraphy and Richards Campbell Sleep Questionnaire (RCSQ).

CONCLUSIONS

Sleep in critically ill patients is severely disturbed, and actigraphy and RCSQ seem reliable alternatives to PSG. Future studies should evaluate impact of sleep disruption on outcomes.

Endocrine dysregulation in aneurysmal subarachnoid haemorrhage

INTRODUCTION

Aneurysmal Subarachnoid haemorrhage (aSAH) is one of the most common causes of neurocritical care admission. Consistent evidence has been suggestive of endocrine dysregulation in aSAH. This review aims to provide an up-to-date presentation of the available evidence regarding endocrine dysregulation in aneurysmal subarachnoid haemorrhage.

METHODS

A comprehensive literature search was performed using PubMed database. All available evidence related to endocrine dysregulation in hypothalamic-pituitary hormones, adrenal hormones and natriuretic peptides after aSAH, published since 2010, were reviewed.

RESULTS

There have been reports of varying prevalence of dysregulation in hypothalamic-pituitary and adrenal hormones in aSAH. The cause of this dysregulation and its pattern remain unclear. Hypothalamic-pituitary and adrenal dysregulation have been associated with higher incidence of poor neurological outcome and increased mortality. Whilst there is evidence that long-term dysregulation of these axes may also develop, it appears to be less frequent than the acute-phase dysregulation and transient in pattern. Increased levels of catecholamines have been reported in the hyper-acute phase of aSAH with reported inconsistent correlation with the outcomes and the complications of the disease. There is growing evidence that of a causal link between the endocrine dysregulation and the development of hyponatraemia and delayed cerebral ischaemia, in the acute phase of aSAH. However, the pathophysiological mechanism and pattern of endocrine dysregulation which could be causally associated with these complications still remain debatable.

CONCLUSION

The evidence, mainly from small observational and heterogeneous in methodology studies, is suggestive of adverse effects of the endocrine dysregulation on the outcome and the incidence of complications of the disease. However, the cause of this dysregulation and a pathophysiological mechanism that could link its presence with the development of acute complications and the outcome of the aSAH remain unclear. Further research is warranted to elucidate the clinical significance of endocrine dysregulation in subarachnoid haemorrhage.

Intensive Care-Related Cognitive Impairment: A Biopsychosocial Overview

Advancements in critical care medicine have improved survival rates for patients experiencing critical illness in intensive care units (ICUs). While mortality has declined, more than half of ICU survivors experience functional impairments that persist beyond discharge. Of particular concern is ICU-related cognitive impairment, which can extend across the care continuum, ranging from acute and transient presentations in the ICU (eg, delirium) to long-term impairments years after discharge. ICU-related cognitive impairment has received increased attention in the literature, particularly as it relates to ICU survivors who have received and survived critical care in the context of SARS-CoV-2 pandemic and are now experiencing post-acute sequelae of SARS-CoV-2 infection. The medical complexity and heterogeneity of ICU survivors, coupled with the multifactorial etiology of ICU-related cognitive impairments, lead to challenges in how to optimize care for ICU survivors at various stages of recovery. This review aims to provide an overview of cognitive outcomes associated with critical illness by integrating recent literature focused on etiology, assessment, and interventions in the context of ICU-related cognitive impairments. The narrative review employs a biopsychosocial framework to comprehensively evaluate the multifactorial nature of ICU-related cognitive outcomes. Authors also highlight multidisciplinary teams composed of key rehabilitation providers are likely best suited for optimizing recovery trajectories of ICU survivors. This article is protected by copyright. All rights reserved.