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

Nonpharmacological interventions to promote sleep in the adult critical patients unit: A scoping review

BACKGROUND

Sleep and circadian rhythms are markedly altered in intensive care unit (ICU) patients. Numerous factors related to the patient and the ICU environment affect the ability to initiate and maintain sleep. Therefore, nonpharmacological interventions could play an essential role in improving sleep and circadian rhythm.

OBJECTIVE

The aim of this study was to examine nonpharmacological interventions evaluated for promoting sleep in adult ICUs.

METHODS

A scoping review was conducted, including randomised controlled trials, nonrandomised controlled trials, quasi-experimental trials, and other controlled studies investigating the effects of nonpharmacological interventions promoting sleep in adult ICU patients.

RESULTS

A total of 57 articles and 14 ongoing trials were included in the review, of which 38 were randomised clinical trials. Nine nonpharmacological interventions to improve sleep in critically ill patients were evaluated: earplugs and/or eye masks, aromatherapy, bundles, music intervention, massage or acupressure, noise masking, bright light, and dynamic light. Most included trials simultaneously assessed the effect of more than one intervention on perceived sleep quality using questionnaires. The association between the interventions and improved sleep varied. In the case of multicomponent interventions, it is difficult to identify which components might have influenced sleep improvement.

CONCLUSIONS

Numerous studies have evaluated various nonpharmacological interventions to promote sleep in critically ill patients, several of which improved perceived sleep quality. However, the substantial variability of the assessed interventions and their implementation complicates drawing reliable conclusions.

REGISTRATION

The protocol for this scoping review was registered with the Open Science Framework under the identifier https://doi.org/10.17605/OSF.IO/MPEQ5.

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.

Validation and the psychometric properties of the Persian version of the sleep quality scale for coronary care patients: a methodological survey

Sleep quality is crucial for recovery in coronary care patients, yet sleep disturbances are prevalent in intensive care settings. This study aimed to validate the Persian version of the Sleep Quality Scale for Coronary Care Patients (SQ-CC-P) in the Iranian population and ensure its psychometric robustness for clinical and research applications. A methodological study was conducted in the Coronary Care Unit (CCU) and heart unit of Imam Khomeini Hospital in Ardabil Province, Iran, from May to September 2024, involving 220 participants diagnosed with acute coronary conditions. The SQ-CC-P, which includes self-assessment and environmental factors, was assessed for content validity, construct validity, and reliability in accordance with COSMIN guidelines. The SQ-CC-P demonstrated strong content validity, with CVI (0.80-0.92), CVR (0.70-1.00), S-CVI/UA (0.85), S-CVI/Ave (0.91), and Adjusted Kappa (0.697) confirming item relevance and necessity. Construct validity was supported by exploratory factor analysis (EFA), which revealed a two-factor structure explaining 62.4% of the variance, and confirmatory factor analysis (CFA), which showed strong factor loadings (0.72-0.82) and excellent model fit. The scale exhibited high internal consistency (Cronbach's alpha = 0.862, McDonald's omega = 0.864) and test-retest reliability (ICC = 0.785, 95% CI [0.718, 0.841]). The SQ-CC-P is a valid and reliable tool for assessing sleep quality among coronary care patients, addressing a critical gap in sleep assessment in intensive care settings.

Are ICU Bedspaces Based in Evidence, and Do They Support Patient Sleep? A Narrative Review

Objective: This narrative review summarizes some of the evidence guiding current intensive care unit (ICU) design, focussing on environmental factors impacting on sleep, and compares available evidence and recommendations to current ICU designs and builds. Background: The importance of sleep for recovery after illness is well known. However, hospitalized patients frequently experience poor and disrupted sleep. This is especially true for patients admitted to the ICU. There are many factors negatively impacting on ICU patients' ability to sleep. Some relate to their illness or pre-existing sleep problems; others relate to patient care activities. While the ICU bedspace may facilitate 24h care, there is growing awareness of the detrimental impact the bedspace environment (especially suboptimal lighting and excessive sound/noise) has on sleep quality, and important questions raised regarding how this may impact on recovery and health outcomes. Multiple guidelines and recommendations exist to guide ICU bedspace design. However, questions have been raised whether contemporary ICUs are evidence-based, and whether the available evidence is effectively translated into the built ICU. Methods: A comprehensive literature review was conducted, exploring the evidence supporting current ICU bedspace design and the impact of ICU design and environmental factors on patient sleep. Results and conclusion: This review summarizes the impact of the ICU bedspace environment on patient outcomes and describes features of the ICU bedspace design that may not adhere to best evidence and contribute to poor sleep. Suggestions on how ICU bedspaces can be improved to optimize sleep are provided.

Sleep and Circadian-Related Outcomes after Critical Illness

Sleep and circadian disruptions are frequently reported in studies of critically ill patients. Less is known about sleep and circadian disruptions after an intensive care unit (ICU) admission. It is recognized now that survivors of critical illness may develop what is termed post-intensive care syndrome (PICS) which is a constellation of symptoms of which two of the most prominent features are fatigue and sleep complaints. Clinicians and researchers are now recognizing the importance of examining symptoms in survivors which impact their quality of life. Although current data are limited this review addresses what is now known about sleep and circadian disruptions post-ICU. Current ongoing research and future studies should continue to inform our understanding of how critical illness and the ICU environment both influence long-term outcomes in critically ill patients.

Sleep Quality of Patients on a General Department During the First Days of Hospitalization

Purpose

The main aim of the study was to record subjective assessment of sleep quality between men and woman in hospitalised patients over 3 nights and look for associations with other basic hospitalisation data (age, type of department, surgery, pain, type of admission, previous hospitalisation, sleep-inducing medication). The secondary aim was to determine whether the Ford Insomnia Response to Stress Test (FIRST) questionnaire is an appropriate tool for identifying hospitalised individuals prone to situational sleep disturbance.

Methods

A multicentre descriptive cross-sectional study was conducted in regular surgical and medical departments of seven selected hospitals in the Czech Republic. On the first day of hospitalization, patients completed the FIRST screening questionnaire. Their subjectively perceived sleep quality for the previous night was assessed from the second to the fourth day of hospitalization using the Richards-Campbell Sleep Questionnaire (RCSQ).

Results

The study included 340 patients (172 females and 168 males; mean age 58.9 ± 14.9 years and 57.3 ± 15.0 years, respectively). No significant differences in RCSQ scores were observed between men and women or across the three nights of hospitalization. Moderate correlations were identified between hospitalization data and RCSQ scores, with the strongest positive correlation for alprazolam use (Ra = 0.604). Other positive correlations included surgical department hospitalization, sleep-inducing medications, surgery, male sex, and age. The strongest negative correlation was with pain (Ra = -0.498), while other negative correlations included elective admission, medical department hospitalization, and previous hospitalization. The studied factors explained 18% of the RCSQ variability. The association between FIRST scores and RCSQ was statistically significant (p < 0.001) but weak (Spearman's -0.1734, Kendall's tau -0.1234).

Conclusion

Subjective sleep quality during hospitalization is related to the type of department, care provided, and pain, age, and sex. There were no significant changes in subjective sleep quality ratings during the first three days of hospitalization. The FIRST questionnaire is not a suitable screening tool for identifying individuals with situational sleep disturbance in hospital.

Prospective cohort study on characteristics, associated factors and short-term prognosis of sleep and circadian rhythm in intensive care unit: protocol for the SYNC study

INTRODUCTION

Acute sleep and circadian rhythm (SCR) disruption can lead to a range of negative physical and mental consequences, such as depression, delirium, respiratory dysfunction and increased mortality. In the intensive care unit (ICU), the unique environment can exacerbate disruptions in SCR. Few studies have identified the characteristics of SCR in the ICU, and the roles of patient characteristics, illness and medical interventions in ICU SCR remain unclear. A single-centre prospective cohort study, called SYNC study (Sleep and circadian rhYthm in iNtensive Care unit), will be conducted to explore the characteristics and associated factors of SCR and investigate the short-term prognosis among patients in the surgical ICU.

METHODS AND ANALYSIS

Patients from a surgical ICU at a tertiary teaching hospital will be enrolled. SCR will be assessed by both objective and subjective indicators, including melatonin secretion rhythm, activity rhythm, sleep pattern and perceived sleep quality. Data on eight potential factors that influence SCR, including light exposure, noise level, pain level, nighttime disturbances, mechanical ventilation, sedative and analgesic use, meal pattern and restraints, will be collected. These data will be gathered in the first 3 days after ICU admission. Short-term prognostic indicators, including anxiety, depression, cognitive function, insomnia, activities of daily living, ICU stay, hospital stay and hospital mortality will be collected during the hospital stay and at 1 month after discharge.

ETHICS AND DISSEMINATION

The study has been approved by the Ethics Committee of Zhongshan Hospital, Fudan University (B2024-076R). The results of this study will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT06346613.

Circadian Rhythms, Immune Regulation, and the Risk for Sepsis: Circadian Rhythms and Neonatal Care

Circadian rhythms provide an anticipatory mechanism for organisms to adapt to environmental changes. Host response to infections is under robust circadian control. Most of the existing literature focuses on adults in epidemiologic and animal studies. Neonatal and early infancy represent critical windows in the consolidation of circadian rhythms. This review summarizes our understanding of the molecular clock, especially its relevance to immunity and adult sepsis. Further, using our knowledge of circadian biology in caring for a newborn host with emerging circadian rhythms represents a unique challenge and an opportunity for improving our approach and outcomes in neonatal sepsis.

Circadian rhythms, metabolism, and nutrition support in critically ill adult patients: a narrative review

PURPOSE OF REVIEW

The human circadian system regulates several physiological processes, including metabolism, which becomes significantly disrupted during critical illness. The common use of 24-h continuous nutrition support feeding in the intensive care unit (ICU) may further exacerbate these disruptions; this review evaluates recent evidence comparing continuous and intermittent feeding schedules in critically ill adults.

RECENT FINDINGS

Research comparing different feeding schedules in critically ill adults remains limited. Recent meta-analyses suggest that continuous and intermittent feeding schedules in the ICU have comparable adverse event profiles, including gastrointestinal intolerance. A retrospective study found that continuous feeding did not impact the 24-h glucose variation in critically ill adults, and a randomized controlled trial reported no significant differences in amino acid, lipid-based, or small molecule metabolite profiles between the two feeding regimens. Potential benefits of intermittent feeding include stimulation of muscle protein synthesis, preservation of normal hormone secretion, and improved attainment of nutritional goals.

SUMMARY

Current evidence suggests comparable safety profiles for continuous and intermittent feeding schedules in critically ill adult patients. However, intermittent and daytime cyclic feeding are expected to align more closely with normal circadian physiology. Given the lack of existing supportive data, a dynamic approach - transitioning from continuous feeding in the early-acute metabolic phase to intermittent feeding or daytime cyclic feeding - may be appropriate.

Chrononutrition in Critical Illness

Circadian rhythms in humans are biological rhythms that regulate various physiological processes within a 24-hour time frame. Critical illness can disrupt the circadian rhythm, as can environmental and clinical factors, including altered light exposure, organ replacement therapies, disrupted sleep-wake cycles, noise, continuous enteral feeding, immobility, and therapeutic interventions. Nonpharmacological interventions, controlling the ICU environment, and pharmacological treatments are among the treatment strategies for circadian disruption. Nutrition establishes biological rhythms in metabolically active peripheral tissues and organs through appropriate synchronization with endocrine signals. Therefore, adhering to a feeding schedule based on the biological clock, a concept known as "chrononutrition," appears to be vitally important for regulating peripheral clocks. Chrononutritional approaches, such as intermittent enteral feeding that includes overnight fasting and consideration of macronutrient composition in enteral solutions, could potentially restore circadian health by resetting peripheral clocks. However, due to the lack of evidence, further studies on the effect of chrononutrition on clinical outcomes in critical illness are needed. The purpose of this review was to discuss the role of chrononutrition in regulating biological rhythms in critical illness, and its impact on clinical outcomes.

Interaction between clock genes, melatonin and cardiovascular outcomes from ICU patients

BACKGROUND

Circadian rhythms, driven by biological clocks, help organisms align their physiological functions with environmental changes, promoting homeostasis. The central clock in the suprachiasmatic nucleus coordinates peripheral clocks via neurohumoral feedback involving proteins like CLOCK, BMAL1, CRY 1/2, and PER 1-3. In the ICU, these circadian processes often face disruptions from constant lighting, noise, and irregular sleep-wake cycles, impairing sleep quality and worsening stress responses. These disruptions can lead to adverse clinical effects, including higher cardiovascular complication rates. This study examines how ICU stays affect circadian rhythm regulators and their association with cardiovascular outcomes.

RESULTS

Significant differences were identified in melatonin levels and the expression of BMAL1, PER1, RORA, and NR1D1 between ICU stays of ≤7 days and >7 days. The APACHE-II severity scale influenced melatonin and the expression of CLOCK, PER2, CRY2, and RORA. Nonlinear relationships were observed between melatonin, clock genes, heart rate, and blood pressure (systolic and diastolic). In certain groups, molecular and physiological data showed correlations exceeding 90%.

CONCLUSIONS

These findings highlight a robust association between circadian disruption, as measured by melatonin and clock genes, and cardiovascular physiological rhythms in ICU patients.

Novel applications of sleep pharmacology as delirium therapeutics

Sleep-wake and circadian disruption (SCD) is a core feature of delirium. It has been hypothesized that SCD contributes to delirium pathogenesis; therefore, interventions that prevent or reverse SCD represent an array of promising opportunities in relation to delirium. This review explores the relationship between sleep-wake/circadian physiology and delirium pathophysiology with a focus on neurotransmitter systems. Across potential targets aimed at preventing or treating delirium, three broad approaches are considered: 1. Pharmacological mechanisms that contribute to physiological sleep may preserve or restore next-day cognition in patients with or at risk for delirium (e.g., alpha 2 agonists, dopamine 2 antagonists, serotonin 2 A antagonists, dual orexin receptor antagonists, or GHB agonists); 2. Pharmacological mechanisms that promote wakefulness during the day may combat hypoactive delirium (e.g., adenosine 2 A antagonists, dopamine transporter antagonists, orexin agonists, histamine 3 antagonists); and 3. Melatonergic and other circadian interventions could strengthen the phase or amplitude of circadian rhythms and ensure appropriately entrained timing in patients with or at risk for delirium (e.g., as informed by a person's preexisting circadian phase).

A pharmacist's guide to mitigating sleep dysfunction and promoting good sleep in the intensive care unit

PURPOSE

To review causes, risk factors, and consequences of sleep disruption in critically ill patients; evaluate the role of nonpharmacological and pharmacological therapies for management of sleep in the intensive care unit (ICU); and discuss the role of pharmacists in implementation of sleep bundles.

SUMMARY

Critically ill patients often have disrupted sleep and circadian rhythm alterations that cause anxiety, stress, and traumatic memories. This can be caused by factors such as critical illness, environmental factors, mechanical ventilation, and medications. Methods to evaluate sleep, including polysomnography and questionnaires, have limitations that should be considered. Multicomponent sleep bundles with a focus on nonpharmacological therapy aiming to reduce nocturnal noise, light, and unnecessary patient care may improve sleep disorders in critically ill patients. While pharmacological agents are often used to facilitate sleep in critically ill patients, evidence supporting their use is often of low quality, which limits use to patients who have sleep disruption refractory to nonpharmacological therapy. Dedicated interprofessional teams are needed for implementation of sleep bundles in the ICU. Extensive pharmacotherapeutic training and participation in daily patient care rounds make pharmacists vital members of the team who can help with all components of the bundle. This narrative review discusses evidence for elements of the multicomponent sleep bundle and provides guidance on how pharmacists can help with implementation of nonpharmacological therapies and management of neuroactive medications to facilitate sleep.

CONCLUSION

Sleep bundles are necessary for patients in the ICU, and dedicated interprofessional teams that include pharmacists are vital for successful creation and implementation.

Pharmacologic Treatment Strategies for Delirium in Hospitalized Adults: Past, Present, and Future

Despite the use of multidomain prevention strategies, delirium still frequently occurs in hospitalized adults. With delirium often associated with undesirable symptoms and deleterious outcomes, including cognitive decline, treatment is important. Risk-factor reduction and the protocolized use of multidomain, nonpharmacologic bundles remain the mainstay of delirium treatment. There is a current lack of strong evidence to suggest any pharmacologic intervention to treat delirium will help resolve it faster, reduce its symptoms (other than agitation), facilitate hospital throughput, or improve post-hospital outcomes including long-term cognitive function. With the exception of dexmedetomidine as a treatment of severe delirium-associated agitation in the ICU, current practice guidelines do not recommend the routine use of any pharmacologic intervention to treat delirium in any hospital population. Future research should focus on identifying and evaluating new pharmacologic delirium treatment interventions and addressing key challenges and gaps surrounding delirium treatment research.

Parental Perspectives From the Survey of Sleep Quality in the PICU Validation Study on Environmental Factors Causing Sleep Disruption in Critically Ill Children

OBJECTIVES

Sleep promotion bundles being tested in PICUs use elements adapted from adult bundles. As children may react differently than adults in ICU environments, this study investigated what parents report disrupted the sleep of their child in a PICU.

DESIGN

Secondary analysis of a multicenter validation study of the Survey of Sleep quality in the PICU.

SETTING

Four Northeastern U.S. PICUs, one hospital-based pediatric sleep laboratory.

PATIENTS

Parents sleeping at the bedside of a child in the PICU or hospital-based sleep laboratory.

INTERVENTIONS

Anonymous one-time survey eliciting parts of hospital or ICU environments that have been described as disruptive to sleep in validated adult ICU and pediatric inpatient questionnaires.

MEASUREMENTS AND MAIN RESULTS

Level of sleep disruption was scored by Likert scale, with higher scores indicating more disruption. Age, demographics, baseline sleep, and PICU exposures were used to describe causes of sleep disruption in a PICU. Of 152 PICU parents, 71% of their children's sleep was disrupted significantly by at least one aspect of being in the PICU. The most prevalent were "being in pain or uncomfortable because they are sick" (38%), "not sleeping at home" (30%), "alarms on machines" (28%), and "not sleeping on their home schedule" (26%). Only 5% were disrupted by excessive nocturnal light exposure. Overall sleep disruption was not different across four PICUs or in those receiving sedation. The validation study control group, healthy children undergoing polysomnography, had less sleep disruption than those in a PICU despite sleeping in a hospital-based sleep laboratory.

CONCLUSIONS

There are multiple aspects of critical care environments that affect the sleep of children, which are different from that of adults, such as disruption to home schedules. Future interventional sleep promotion bundles should include sedated children and could be applicable in multicenter settings.

The Nurse-Implemented Chronotherapeutic Bundle in Critically Ill Children, RESTORE Resilience (R 2 ): Pilot Testing in a Two-Phase Cohort Study, 2017-2021

OBJECTIVES

Pilot test the nurse-led chronotherapeutic bundle in critically ill children, RESTORE Resilience (R 2 ).

DESIGN

A two-phase cohort study was carried out from 2017 to 2021.

SETTING

Two similarly sized and organized PICUs in the United States.

PATIENTS

Children 6 months to 17 years old who were mechanically ventilated for acute respiratory failure.

INTERVENTIONS

R 2 seven-item chronotherapeutic bundle, including: 1) replication of child's pre-hospital daily routine (i.e., sleep/wake, feeding, activity patterns); 2) cycled day-night light/sound modulation; 3) minimal effective sedation; 4) night fasting with bolus enteral daytime feedings; 5) early progressive mobility; 6) nursing care continuity; and 7) parent diaries.

MEASUREMENTS AND MAIN RESULTS

Children underwent environmental (light, sound) and patient (actigraphy, activity log, salivary melatonin, electroencephalogram) monitoring. Parents completed the Child's Daily Routine and Sleep Survey (CDRSS) and Family-Centered Care Scale. The primary outcome was post-extubation daytime activity consolidation (Daytime Activity Ratio Estimate [DARE]). Twenty baseline-phase (2017-2019) and 36 intervention-phase (2019-2021) participants were enrolled. During the intervention phase, nurses used the CDRSS to construct children's PICU schedules. Overall compliance with nurse-implemented R 2 elements 1-5 increased from 18% (interquartile range, 13-30%) at baseline to 63% (53-68%) during the intervention phase ( p < 0.001). Intervention participants were exposed to their pre-hospitalization daily routine ( p = 0.002), cycled day-night light/sound modulation ( p < 0.001), and early progressive mobility on more PICU days ( p = 0.02). Sedation target identification, enteral feeding schedules, and nursing care continuity did not differ between phases. Parent diaries were seldom used. DARE improved during the intervention phase and was higher pre-extubation (median 62% vs. 53%; p = 0.04) but not post-extubation (62% vs. 57%; p = 0.56).

CONCLUSIONS

In the PICU, implementation of an individualized nurse-implemented chronotherapeutic bundle is feasible. Children who received the R 2 bundle had increased pre-extubation daytime activity consolidation compared to children receiving usual care. Given variation in protocol adherence, further R 2 testing should include interprofessional collaboration, pragmatic trial design, and implementation science strategies.

Intensive care unit interventions to promote sleep and circadian biology in reducing incident delirium: a scoping review

RATIONALE/OBJECTIVES

Despite plausible pathophysiological mechanisms, research is needed to confirm the relationship between sleep, circadian rhythm and delirium in patients admitted to the intensive care unit (ICU). The objective of this review is to summarise existing studies promoting, in whole or in part, the normalisation of sleep and circadian biology and their impact on the incidence, prevalence, duration and/or severity of delirium in ICU.

METHODS

A sensitive search of electronic databases and conference proceedings was completed in March 2023. Inclusion criteria were English-language studies of any design that evaluated in-ICU non-pharmacological, pharmacological or mixed intervention strategies for promoting sleep or circadian biology and their association with delirium, as assessed at least daily. Data were extracted and independently verified.

RESULTS

Of 7886 citations, we included 50 articles. Commonly evaluated interventions include care bundles (n=20), regulation or administration of light therapy (n=5), eye masks and/or earplugs (n=5), one nursing care-focused intervention and pharmacological intervention (eg, melatonin and ramelteon; n=19). The association between these interventions and incident delirium or severity of delirium was mixed. As multiple interventions were incorporated in included studies of care bundles and given that there was variable reporting of compliance with individual elements, identifying which components might have an impact on delirium is challenging.

CONCLUSIONS

This scoping review summarises the existing literature as it relates to ICU sleep and circadian disruption (SCD) and delirium in ICU. Further studies are needed to better understand the role of ICU SCD promotion interventions in delirium mitigation.

Light, sleep and circadian rhythm in critical illness

PURPOSE OF REVIEW

Sleep and circadian disruption (SCD) are associated with worse outcomes in the ICU population. We discuss sleep, circadian physiology, the role of light in circadian entrainment and its possible role in treating SCD, with special attention to the use of light therapies and ICU design.

RECENT FINDINGS

The American Thoracic Society recently published an official research statement highlighting key areas required to define and treat ICU SCD. Recent literature has been predominantly observational, describing how both critical illness and the ICU environment might impair normal sleep and impact circadian rhythm. Emerging consensus guidance outlines the need for standardized light metrics in clinical trials investigating effects of light therapies. A recent proof-of-concept randomized controlled trial (RCT) showed improvement in delirium incidence and circadian alignment from ICU room redesign that included a dynamic lighting system (DLS).

SUMMARY

Further investigation is needed to define the optimal physical properties of light therapy in the ICU environment as well as timing and duration of light treatments. Work in this area will inform future circadian-promoting design, as well as multicomponent nonpharmacological protocols, to mitigate ICU SCD with the objective of improving patient outcomes.

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.

Inactivity May Identify Older Intensive Care Unit Survivors at Risk for Post-Intensive Care Syndrome

BACKGROUND

Older adults (≥age 65) admitted to an intensive care unit (ICU) are profoundly inactive during hospitalization. Older ICU survivors often experience life-changing symptoms, including cognitive dysfunction, physical impairment, and/or psychological distress, which are components of post-intensive care syndrome (PICS).

OBJECTIVES

To explore trends between inactivity and symptoms of PICS in older ICU survivors.

METHODS

This study was a secondary analysis of pooled data obtained from 2 primary, prospective, cross-sectional studies of older ICU survivors. After ICU discharge, 49 English- and Spanish-speaking participants who were functionally independent before admission and who had received mechanical ventilation while in the ICU were enrolled. Actigraphy was used to measure post-ICU hourly activity counts (12:00 AM to 11:59 PM). Selected instruments from the National Institutes of Health Toolbox and Patient-Reported Outcomes Measurement Information System were used to assess symptoms of PICS: cognitive dysfunction, physical impairment, and psychological distress.

RESULTS

Graphs illustrated trends between inactivity and greater symptom severity of PICS: participants who were less active tended to score worse than one standard deviation of the mean on each outcome. Greater daytime activity was concurrently observed with higher performances on cognitive and physical assessments and better scores on psychological measures.

CONCLUSIONS

Post-ICU inactivity may identify older ICU survivors who may be at risk for PICS and may guide future research interventions to mitigate symptom burden.

The pathogenesis of influenza in intact alveoli: virion endocytosis and its effects on the lung's air-blood barrier

Lung infection by influenza A virus (IAV) is a major cause of global mortality from lung injury, a disease defined by widespread dysfunction of the lung's air-blood barrier. Endocytosis of IAV virions by the alveolar epithelium - the cells that determine barrier function - is central to barrier loss mechanisms. Here, we address the current understanding of the mechanistic steps that lead to endocytosis in the alveolar epithelium, with an eye to how the unique structure of lung alveoli shapes endocytic mechanisms. We highlight where future studies of alveolar interactions with IAV virions may lead to new therapeutic approaches for IAV-induced lung injury.

A Rapid Systematic Review of Pharmacologic Sleep Promotion Modalities in the Intensive Care Unit

Background: The Society of Critical Care Medicine Clinical Practice Guidelines for Management of Pain, Agitation, Delirium, Immobility, and Sleep recommend protocolized non-pharmacologic sleep improvement. Pharmacologic interventions are frequently initiated to promote sleep but the evidence supporting these strategies remains controversial. Purpose: To systematically search and synthesize evidence evaluating pharmacologic sleep promotion modalities in critically ill adults. Methods: A rapid systematic review protocol was used to search Medline, Cochrane Library, and Embase for reports published through October 2022. We included randomized controlled trials (RCTs) and before-and-after cohort studies evaluating pharmacologic modalities intended to improve sleep in adult intensive care unit (ICU) patients. Sleep-related endpoints were the primary outcome of interest. Study and patient characteristics and relevant safety and non-sleep outcome data were also collected. The Cochrane Collaboration Risk of Bias or Risk of Bias in Non-Randomized Studies of Interventions were used to assess the risk of bias for all included studies. Results: Sixteen studies (75% RCTs) enrolling 2573 patients were included; 1207 patients were allocated to the pharmacologic sleep intervention. Most studies utilized dexmedetomidine (7/16; total n = 505 patients) or a melatonin agonist (6/16; total n = 592 patients). Only half of the studies incorporated a sleep promotion protocol as standard of care. Most (11/16, 68.8%) studies demonstrated a significant improvement in ≥1 sleep endpoint (n = 5 dexmedetomidine, n = 3 melatonin agonists, n = 2 propofol/benzodiazepines). Risk of bias was generally low for RCTs and moderate-severe for cohort studies. Conclusions: Dexmedetomidine and melatonin agonists are the most studied pharmacologic sleep promotion modalities, but current evidence does not support their routine administration in the ICU to improve sleep. Future RCTs evaluating pharmacologic modalities for ICU sleep should consider patients' baseline and ICU risks for disrupted sleep, incorporate a non-pharmacologic sleep improvement protocol, and evaluate the effect of these medication interventions on circadian rhythm, physiologic sleep, patient-perceived sleep quality, and delirium.

Pediatric Intensive Care Unit related Sleep and Circadian Dysregulation: a focused review

The pediatric intensive care unit (PICU) is bright, loud, and disruptive to children. Strategies to improve the sleep of adults in the ICU have improved delirium and mortality rates. Children need more sleep than adults for active growth, healing, and development when well; this is likely true when they are critically ill. This review was performed to describe what we know in this area to date with the intent to identify future directions for research in this field. Since the 1990s, 16 articles on 14 observational trials have been published investigating the sleep on a total of 312 critically ill children and the melatonin levels of an additional 144. Sleep measurements occurred in 9 studies through bedside observation (n = 2), actigraphy (n = 2), electroencephalogram (n = 1) and polysomnography (n = 4), of which polysomnography is the most reliable. Children in the PICU sleep more during the day, have fragmented sleep and disturbed sleep architecture. Melatonin levels may be elevated and peak later in critically ill children. Early data suggest there are at-risk subgroups for sleep and circadian disruption in the PICU including those with sepsis, burns, traumatic brain injury and after cardiothoracic surgery. The available literature describing the sleep of critically ill children is limited to small single-center observational studies with varying measurements of sleep and inconsistent findings. Future studies should use validated measurements and standardized definitions to begin to harmonize this area of medicine to build toward pragmatic interventional trials that may shift the paradigm of care in the pediatric intensive care unit.

Disruption of the circadian rhythm of melatonin: A biomarker of critical illness severity

Circadian dysrhythmias occur commonly in critically ill patients reflecting variable effects of underlying illness, ICU environment, and treatments. We retrospectively analyzed the relationship between clinical outcomes and 24-h urinary 6-sulfatoxymelatonin (aMT6s) excretion profiles in 37 critically ill patients with shock and/or respiratory failure. Nonlinear regression was used to fit a 24-h cosine curve to each patient's aMT6s profile, with rhythmicity determined by the zero-amplitude test. From these curves we determined acrophase, amplitude, phase, and night/day ratio. After assessing unadjusted relationships, we identified the optimal multivariate models for hospital survival and for discharge to home (vs. death or transfer to another facility). Normalized aMT6s rhythm amplitude was greater (p = 0.005) in patients discharged home than in those who were not, while both groups exhibited a phase delay. Patients with rhythmic aMT6s excretion were more likely to survive (OR 5.25) and be discharged home (OR 8.89; p < 0.05 for both) than patients with arrhythmic profiles, associations that persisted in multivariate modelling. In critically ill patients with shock and/or respiratory failure, arrhythmic and/or low amplitude 24-h aMT6s rhythms were associated with worse clinical outcomes, suggesting a role for the melatonin-based rhythm as a novel biomarker of critical illness severity.

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.

[Non-pharmacological Management of Postoperative Delirium]

Postoperative delirium is common especially in the elderly and is associated with high rates of morbidity and mortality. Non-pharmacological multicomponent interventions are effective in reducing the incidence and to a degree the duration of postoperative delirium and are recommended in international guidelines on postoperative delirium as first line intervention for management of delirium. Non-pharmacological management of postoperative delirium consists of strategies for risk stratification, risk reduction by non-pharmacological bundle interventions, early recognition of delirium by screening protocols and immediate therapy of underlying causes of delirium and continuation of non-pharmacological bundles. Non-pharmacological bundle interventions address common perioperative risk factors. Bundles comprise strategies for oxygenation, mobilization, hydration and nutrition, sensory and cognitive stimulation, reorientation, modifications of environmental factors such as design aspects and noise reduction, adequate analgesia, management of agitation and anxiety, protecting circadian rhythms for example by adequate light exposure during daytime, family involvement and timely reduction of unnecessary catheters and anticholinergic drugs. The article aims at providing an overview of non-pharmacological management of postoperative delirium in the hospital.

Melatonin Use in Pediatric Intensive Care Units: A Single-Center Experience

Growing evidence indicates that altered melatonin secretion during critical illness may influence the quality and quantity of sleep, delirium, and overall recovery. However, limited data exist regarding the use of melatonin in pediatric critical illness. Data were reviewed over a 5-year period at a tertiary pediatric intensive care unit for pediatric patients (ages 0-18 years) who were prescribed melatonin with the aim of identifying the frequency of and indications for use. Data collection included the hospital day of initiation, the dose, the frequency, the duration of use, and the length of stay. The results demonstrate that melatonin was infrequently prescribed (6.0% of patients admitted; n = 182) and that the majority of patients received melatonin as continuation of home medication (46%; n = 83 of 182). This group had significantly earlier melatonin use (0.9 ± 2.3 day of hospitalization; p < 0.0001) and significantly reduced lengths of stay compared to the other groups (mean LOS 7.2 ± 9.3 days; p < 0.0001). Frequently, clear documentation of indication for melatonin use was absent (20%; n = 37). In conclusion, given that melatonin is infrequently used within a tertiary PICU with the most common indication as the continuation of home medication, and often without clear documentation for indication, this presents an opportunity to emphasize a more attentive and strategic approach regarding melatonin use in the PICU population.