Obstructive sleep apnea and delirium: exploring possible mechanisms

Association Between Preoperative Sleep Disturbance and Postoperative Delirium in Elderly: A Retrospective Cohort Study

Purpose

Postoperative sleep disturbance, characterized by diminished postoperative sleep quality, is a risk factor for postoperative delirium (POD); however, the association between pre-existing sleep disturbance and POD remains unclear. This study aimed to evaluate the association between preoperative sleep disturbance and POD in elderly patients after non-cardiac surgery.

Patients and methods

This retrospective cohort study was conducted at a single center and enrolled 489 elderly patients who underwent surgery between May 1, 2020, and March 31, 2021. Patients were divided into the sleep disorder (SD) and non-sleep disorder (NSD) groups according to the occurrence of one or more symptoms of insomnia within one month or sleep- Numerical Rating Scale (NRS)≥6 before surgery. The primary outcome was the incidence of POD. Propensity score matching analysis was performed between the two groups. Multiple logistic regression analysis was performed to identify the risk factors for POD.

Results

In both the unmatched cohort (16.0% vs 6.7%, P=0.003) and the matched cohort (17.0% vs 6.2%, P=0.023), the incidence of POD was higher in the SD group than in the NSD group. In addition, the postoperative sleep quality and the VAS score at postoperative 24 h were significantly lower in the SD group than in the NSD group. Multivariate logistic regression analysis indicated that age (Odds Ratio, 1.13 [95% CI: 1.04-1.23], P=0.003) and preoperative sleep disturbance (Odds Ratio, 3.03 [95% CI: 1.09-9.52], P=0.034) were independent risk factors for the development of POD.

Conclusion

The incidence of POD was higher in patients with pre-existing sleep disturbance than those without it. Whether improving sleep quality for preoperative sleep disturbance may help prevent POD remains to be determined.

Sleep Loss the night before surgery and incidence of postoperative delirium in adults 65-95 years of age

STUDY OBJECTIVES

To describe the association between preoperative sleep disruption and postoperative delirium.

METHODS

Prospective cohort study with six time points (3 nights pre-hospitalization and 3 nights post-surgery). The sample included 180 English-speaking patients ≥65 years old scheduled for major non-cardiac surgery and anticipated minimum hospital stay of 3 days. Six days of wrist actigraphy recorded continuous movement to estimate wake and sleep minutes during the night from 22:00 to 05:59. Postoperative delirium was measured by a structured interview using the Confusion Assessment Method. Sleep variables for patients with (n = 32) and without (n = 148) postoperative delirium were compared using multivariate logistic regression.

RESULTS

Participants had a mean age of 72 ± 5 years (range 65-95 years). The incidence of postoperative delirium during any of the three postoperative days was 17.8%. Postoperative delirium was significantly associated with surgery duration (OR = 1.49, 95% CI 1.24-1.83) and sleep loss >15% on the night before surgery (OR = 2.64, 95% CI 1.10-6.62). Preoperative symptoms of pain, anxiety and depression were unrelated to preoperative sleep loss.

CONCLUSIONS

In this study of adults ≥65 years of age, short sleep duration was more severe preoperatively in the patients who experienced postoperative delirium as evidenced by sleep loss >15% of their normal night's sleep. However, we were unable to identify potential reasons for this sleep loss. Further investigation should include additional factors that may be associated with preoperative sleep loss to inform potential intervention strategies to mitigate preoperative sleep loss and reduce risk of postoperative delirium.

Assessment of Quality of Life and Symptoms in Non Syndromic Paediatric Obstructive Sleep Apnoea Patients: Before and After Adenotonsillectomy

This study aims to assess the improvement in quality of life and symptoms in paediatric obstructive sleep apnoea patients before and after adenotonsillectomy. From all paediatric patients who presented to our OPD with complaints of mouth breathing and snoring, a subset of patients fulfilling our inclusion criteria were selected and evaluated with PSQSRBD scale, quality of life (QoL) inventory and PSG level-III. Later37 patients who had moderate to severe OSA were selected for study and underwent adenotonsillectomy. They were further followed up postoperatively at 3 months and 7 months with PSQSRBD Scale and QoL inventory. The study cohort had 37 patients with moderate to severe OSA, with a mean age of 8yrs.The postoperative (mean of 3rd and 7th month) values of PSQSRBD Scale and QoL inventory values was significantly (p < 0.001) reduced compared to preoperative Values after adenotonsillectomy. There is statistically significant correlation between adenoid and tonsil size to the relief of symptoms (PSQSRBD SCALE values) and improvement of quality of life. In our study, surgical (adenotonsillectomy) intervention has significant effect in management of moderate to severe non syndromic paediatric OSA patients.

Risk factors for postoperative delirium following total hip or knee arthroplasty: A meta-analysis

Objectives

The purpose of this study was to identify risk factors for delirium after total joint arthroplasty (TJA) and provide theoretical guidance for reducing the incidence of delirium after TJA.

Methods

The protocol for this meta-analysis is registered with PROSPERO (CRD42020170031). We searched PubMed, the Cochrane Library and Embase for observational studies on risk factors for delirium after TJA. Review Manager 5.3 was used to calculate the relative risk (RR) or standard mean difference (SMD) of potential risk factors related to TJA. STATA 14.0 was used for quantitative publication bias evaluation.

Results

In total, 25 studies including 3,767,761 patients from 9 countries were included. Old age has been widely recognized as a risk factor for delirium. Our results showed that the main risk factors for delirium after TJA were patient factors (alcohol abuse: RR = 1.63; length of education: SMD = −0.93; and MMSE score: SMD = −0.39), comorbidities (hypertension: RR = 1.26; diabetes mellitus: RR = 1.67; myocardial infarction: RR = 17.75; congestive heart failure: RR = 2.54; dementia: RR = 17.75; renal disease: RR = 2.98; history of stroke: RR = 4.83; and history of mental illness: RR = 2.36), surgical factors (transfusion: RR = 1.53; general anesthesia: RR = 1.10; pre-operative albumin: SMD = −0.38; pre-operative hemoglobin: SMD = −0.29; post-operative hemoglobin: SMD = −0.24; total blood loss: SMD = 0.15; duration of surgery: SMD = 0.29; and duration of hospitalization: SMD = 2.00) and drug factors (benzodiazepine use: RR = 2.14; ACEI use: RR = 1.52; and beta-blocker use: RR = 1.62).

Conclusions

Multiple risk factors were associated with delirium after TJA. These results may help doctors predict the occurrence of delirium after surgery and determine the correct treatment.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42020170031.

Sleep, Pain, and Cognition: Modifiable Targets for Optimal Perioperative Brain Health

The prevention of perioperative neurocognitive disorders is a priority for patients, families, clinicians, and researchers. Given the multiple risk factors present throughout the perioperative period, a multicomponent preventative approach may be most effective. The objectives of this narrative review are to highlight the importance of sleep, pain, and cognition on the risk of perioperative neurocognitive disorders and to discuss the evidence behind interventions targeting these modifiable risk factors. Sleep disruption is associated with postoperative delirium, but the benefit of sleep-related interventions is uncertain. Pain is a risk factor for postoperative delirium, but its impact on other postoperative neurocognitive disorders is unknown. Multimodal analgesia and opioid avoidance are emerging as best practices, but data supporting their efficacy to prevent delirium are limited. Poor preoperative cognitive function is a strong predictor of postoperative neurocognitive disorder, and work is ongoing to determine whether it can be modified to prevent perioperative neurocognitive disorders.

Suppression of CHOP Reduces Neuronal Apoptosis and Rescues Cognitive Impairment Induced by Intermittent Hypoxia by Inhibiting Bax and Bak Activation

Our previous study showed that growth arrest- and DNA damage-inducible gene 153 (GAD153/CHOP) plays an important role in intermittent hypoxia- (IH-) induced apoptosis and impaired synaptic plasticity. This study is aimed at determining which signaling pathway is activated to induce CHOP and the role of this protein in mitochondria-dependent apoptosis induced by IH. In the in vivo study, mice were placed in IH chambers for 8 h daily over a period of 2 weeks; the IH chambers had oxygen (O₂) concentrations that oscillated between 10% and 21%, cycling every 90 s. In the in vitro study, PC12 cells were exposed to 21% O₂ (normoxia) or 8 IH cycles (25 min at 21% O₂ and 35 min at 0.1% O₂ for each cycle). After 2 weeks of IH treatment, we observed that the expression levels of phosphorylated protein kinase-like endoplasmic reticulum kinase (p-PERK), activating transcription factor 4 (ATF-4) and phosphorylated eukaryotic initiation factor 2 alpha (p-elf2α), were increased, but the levels of activating transcription factor 6 (ATF-6) and inositol-requiring enzyme 1 (IRE-1) were not increased. GSK2606414, a specific chemical inhibitor of the PERK pathway, reduced the expression of p-PERK, ATF-4, p-elf2α, and CHOP and rescued ER structure. In addition, Bax and Bak accumulated in the mitochondria after IH treatment, which induced cytochrome c release and initiated apoptosis. These effects were prevented by GSK2606414 and CHOP shRNA. Finally, the impaired long-term potentiation and long-term spatial memory in the IH group were rescued by GSK2606414. Together, the data from the in vitro and in vivo experiments indicate that IH-induced apoptosis and impaired synaptic plasticity were mediated by the PERK-ATF-4-CHOP pathway. Suppressing PERK-ATF-4-CHOP signaling pathway attenuated mitochondria-dependent apoptosis by reducing the expression of Bax and Bak in mitochondria, which may serve as novel adjunct therapeutic strategy for ameliorating obstructive sleep apnea- (OSA-) induced neurocognitive impairment.

Perioperative Sleep Disorder: A Review

Patients in the perioperative period usually present with different types and degrees of sleep disorders, which can severely affect their post-operative outcomes. Multiple risk factors may lead to the occurrence of perioperative sleep disorders, including personal factors, psychological factors, surgery factors, and environmental factors. In this review, we summarize the potential risk factors for perioperative sleep disorders during hospitalization. And it also provides an overview of perioperative outcomes and potential therapeutic prevention of perioperative sleep disorders. However, the further search is necessary to investigate the effectiveness and safety of preventions in the clinical practice and push forward the therapies.

Global burden of sleep-disordered breathing and its implications

One-seventh of the world's adult population, or approximately one billion people, are estimated to have OSA. Over the past four decades, obesity, the main risk factor for OSA, has risen in striking proportion worldwide. In the past 5 years, the WHO estimates global obesity to affect almost two billion adults. A second major risk factor for OSA is advanced age. As the prevalence of the ageing population and obesity increases, the vulnerability towards having OSA increases. In addition to these traditional OSA risk factors, studies of the global population reveal select contributing features and phenotypes, including extreme phenotypes and symptom clusters that deserve further examination. Untreated OSA is associated with significant comorbidities and mortality. These represent a tremendous threat to the individual and global health. Beyond the personal toll, the economic costs of OSA are far-reaching, affecting the individual, family and society directly and indirectly, in terms of productivity and public safety. A better understanding of the pathophysiology, individual and ethnic similarities and differences is needed to better facilitate management of this chronic disease. In some countries, measures of the OSA disease burden are sparse. As the global burden of OSA and its associated comorbidities are projected to further increase, the infrastructure to diagnose and manage OSA will need to adapt. The use of novel approaches (electronic health records and artificial intelligence) to stratify risk, diagnose and affect treatment are necessary. Together, a unified multi-disciplinary, multi-organizational, global approach will be needed to manage this disease.

Association Between Preoperative Obstructive Sleep Apnea and Preoperative Positive Airway Pressure With Postoperative Intensive Care Unit Delirium

IMPORTANCE

Obstructive sleep apnea has been associated with postoperative delirium, which predisposes patients to major adverse outcomes. Positive airway pressure may be an effective intervention to reduce delirium in this population.

OBJECTIVES

To determine if preoperative obstructive sleep apnea is associated with postoperative incident delirium in the intensive care unit and if preoperative positive airway pressure adherence modifies the association.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective single-center cohort study was conducted at a US tertiary hospital from November 1, 2012, to August 31, 2016, among 7792 patients admitted to an intensive care unit who underwent routine Confusion Assessment Method for the intensive care unit after major surgery. Patients were adults who had undergone a complete preoperative anesthesia assessment, received general anesthesia, underwent at least 1 delirium assessment, were not delirious preoperatively, and had a preoperative intensive care unit stay of less than 6 days. Statistical analysis was conducted from August 20, 2019, to January 11, 2020.

EXPOSURES

Self-reported obstructive sleep apnea, billing diagnosis of obstructive sleep apnea, or STOP-BANG (Snoring, Tiredness, Observed Apnea, Blood Pressure, Body Mass Index, Age, Neck Circumference and Gender) questionnaire score greater than 4, as well as self-reported use of preoperative positive airway pressure.

MAIN OUTCOMES AND MEASURES

Delirium within 7 days of surgery.

RESULTS

A total of 7792 patients (4562 men; mean [SD] age, 59.2 [15.3] years) met inclusion criteria. Diagnosed or likely obstructive sleep apnea occurred in 2044 patients (26%), and delirium occurred in 3637 patients (47%). The proportion of patients with incident delirium was lower among those with obstructive sleep apnea than those without (897 of 2044 [44%] vs 2740 of 5748 [48%]; unadjusted risk difference, -0.04; 99% credible interval [CrI], -0.07 to -0.00). Positive airway pressure adherence had minimal association with delirium (risk difference, -0.00; 99% CrI, -0.09 to 0.09). Doubly robust confounder adjustment eliminated the association between obstructive sleep apnea and delirium (risk difference, -0.01; 99% CrI, -0.04 to 0.03) and did not change that of preoperative positive airway pressure adherence (risk difference, -0.00, 99% CrI, -0.07 to 0.07). The results were consistent across multiple sensitivity analyses.

CONCLUSIONS AND RELEVANCE

After risk adjustment, this study found no association between obstructive sleep apnea and postoperative delirium in the context of usual care in the intensive care unit, with 99% CrIs excluding clinically meaningful associations. With limited precision, no association was found between positive airway pressure adherence and delirium. Selection bias and measurement error limit the validity and generalizability of these observational associations; however, they suggest that interventions targeting sleep apnea and positive airway pressure are unlikely to have a meaningful association with postoperative intensive care unit delirium.

Obstructive sleep apnoea, positive airway pressure treatment and postoperative delirium: protocol for a retrospective observational study

INTRODUCTION

Obstructive sleep apnoea (OSA) is common among older surgical patients, and delirium is a frequent and serious postoperative complication. Emerging evidence suggests that OSA increases the risk for postoperative delirium. We hypothesise that OSA is an independent risk factor for postoperative delirium, and that in patients with OSA, perioperative adherence to positive airway pressure (PAP) therapy decreases the incidence of postoperative delirium and its sequelae. The proposed retrospective cohort analysis study will use existing datasets to: (i) describe and compare the incidence of postoperative delirium in surgical patients based on OSA diagnosis and treatment with PAP; (ii) assess whether preoperatively untreated OSA is independently associated with postoperative delirium; and (iii) explore whether preoperatively untreated OSA is independently associated with worse postoperative quality of life (QoL). The findings of this study will inform on the potential utility and approach of an interventional trial aimed at preventing postoperative delirium in patients with diagnosed and undiagnosed OSA.

METHODS AND ANALYSIS

Observational data from existing electronic databases will be used, including over 100 000 surgical patients and ~10 000 intensive care unit (ICU) admissions. We will obtain the incidence of postoperative delirium in adults admitted postoperatively to the ICU who underwent structured preoperative assessment, including OSA diagnosis and screening. We will use doubly robust propensity score methods to assess whether untreated OSA independently predicts postoperative delirium. Using similar methodology, we will assess if untreated OSA independently predicts worse postoperative QoL.

ETHICS AND DISSEMINATION

This study has been approved by the Human Research Protection Office at Washington University School of Medicine. We will publish the results in a peer-reviewed venue. Because the data are secondary and high risk for reidentification, we will not publicly share the data. Data will be destroyed after 1 year of completion of active Institutional Review Board (IRB) approved projects.

Prevention of postoperative delirium in elderly patients planned for elective surgery: systematic review and meta-analysis

Introduction: Vulnerable or “frail” patients are susceptible to the development of delirium when exposed to triggers such as surgical procedures. Once delirium occurs, interventions have little effect on severity or duration, emphasizing the importance of primary prevention. This review provides an overview of interventions to prevent postoperative delirium in elderly patients undergoing elective surgery.

Methods: A literature search was conducted in March 2018. Randomized controlled trials (RCTs) and before-and-after studies on interventions with potential effects on postoperative delirium in elderly surgical patients were included. Acute admission, planned ICU admission, and cardiac patients were excluded. Full texts were reviewed, and quality was assessed by two independent reviewers. Primary outcome was the incidence of delirium. Secondary outcomes were severity and duration of delirium. Pooled risk ratios (RRs) were calculated for incidences of delirium where similar intervention techniques were used.

Results: Thirty-one RCTs and four before-and-after studies were included for analysis. In 19 studies, intervention decreased the incidences of postoperative delirium. Severity was reduced in three out of nine studies which reported severity of delirium. Duration was reduced in three out of six studies. Pooled analysis showed a significant reduction in delirium incidence for dexmedetomidine treatment, and bispectral index (BIS)-guided anaesthesia. Based on sensitivity analyses, by leaving out studies with a high risk of bias, multicomponent interventions and antipsychotics can also significantly reduce the incidence of delirium.

Conclusion: Multicomponent interventions, the use of antipsychotics, BIS-guidance, and dexmedetomidine treatment can successfully reduce the incidence of postoperative delirium in elderly patients undergoing elective, non-cardiac surgery. However, present studies are heterogeneous, and high-quality studies are scarce. Future studies should add these preventive methods to already existing multimodal and multidisciplinary interventions to tackle as many precipitating factors as possible, starting in the pre-admission period.

Preoperative STOP-BANG Scores and Postoperative Delirium and Coma in Thoracic Surgery Patients

BACKGROUND

Obstructive sleep apnea (OSA) is associated with higher rates of postoperative delirium. The relationship between preoperative OSA risk and postoperative delirium and coma in thoracic surgery patients hospitalized in the intensive care unit (ICU) is not well understood. This study tests the hypothesis that thoracic surgery patients hospitalized in ICU with a higher preoperative risk for OSA are more likely to develop postoperative delirium and coma, resulting in longer hospital stays.

METHODS

Preoperative OSA risk was measured using the STOP-BANG questionnaire. STOP-BANG scores of greater than or equal to 3 were defined as intermediate-high risk for OSA; 128 patients who underwent major thoracic surgery completed the STOP-BANG questionnaire preoperatively. The Richmond Agitation and Sedation Scale was used to assess level of consciousness. The Confusion Assessment Method for the ICU was used to assess for delirium. Linear regression was used to assess the relationship between risk of OSA and outcome measures. Results were adjusted for age, sex, body mass index, Charlson Comorbidity Index, instrumental activities of daily living, and surgery type.

RESULTS

A total of 96 of 128 patients (76%) were in the intermediate-high-risk OSA group. Adjusted analyses showed that the intermediate-high-risk OSA group had a longer duration of postoperative ICU delirium and coma compared with the low-risk OSA group (1.4 ± 1.3 days versus 0.9 ± 1.4 days; P = 0.04). Total number of hospital days was not significantly different.

CONCLUSIONS

Higher preoperative risk for OSA in thoracic surgery patients was associated with a longer duration of postoperative delirium and coma.

Impact on the brain of the inflammatory response to surgery

The brain is both the orchestrator as well as the target of the innate immune system's response to the aseptic trauma of surgery. When trauma-induced inflammation is not appropriately regulated persistent neuro-inflammation interferes with the synaptic plasticity that underlies the learning and memory aspects of cognition. The complications that ensue, include postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) at two poles of a constellation that is now termed perioperative neurocognitive disorders. While the relationship of acute POD to the more indolent POCD is not completely understood both can be further complicated by earlier-onset of dementia and higher mortality. How and why these disorders occur is the focus of this report. The innate immune system response to peripheral trauma signals to the brain through a regulated cascade of cellular and molecular actors producing a teleological defense mechanism, "sickness behavior," to curtail further injury and initiate repair. Sickness behavior, including disordered cognition, is terminated by neural and humoral pathways that restore homeostasis and launch the organism on a path to good health. With so many "moving parts" the innate immune system is vulnerable in clinical settings that include advanced age and lifestyle-induced diseases such as "unhealthy" obesity and the inevitable insulin resistance. Under these conditions, inflammation may become exaggerated and long-lived. Consideration is provided how to identify the high-risk surgical patient and both pharmacological (including biological compounds) and non-pharmacological strategies to customize care.

Decreasing Delirium through Music (DDM) in critically ill, mechanically ventilated patients in the intensive care unit: study protocol for a pilot randomized controlled trial

Background

Delirium is a highly prevalent and morbid syndrome in intensive care units (ICUs). Changing the stressful environment within the ICU via music may be an effective and a scalable way to reduce the burden of delirium.

Methods/design

The Decreasing Delirium through Music (DDM) study is a three-arm, single-blind, randomized controlled feasibility trial.

Sixty patients admitted to the ICU with respiratory failure requiring mechanical ventilation will be randomized to one of three arms (20 participants per arm): (1) personalized music, (2) non-personalized relaxing music, or (3) attention-control. Music preferences will be obtained from all enrolled participants or their family caregivers. Participants will receive two 1-h audio sessions a day through noise-cancelling headphones and mp3 players. Our primary aim is to determine the feasibility of the trial design (recruitment, adherence, participant retention, design and delivery of the music intervention). Our secondary aim is to estimate the potential effect size of patient-preferred music listening in reducing delirium, as measured by the Confusion Assessment Method for the ICU (CAM-ICU). Participants will receive twice daily assessments for level of sedation and presence of delirium. Enrolled participants will be followed in the hospital until death, discharge, or up to 28 days, and seen in the Critical Care Recovery Clinic at 90 days.

Discussion

DDM is a feasibility trial to provide personalized and non-personalized music interventions for critically ill, mechanically ventilated patients. Our trial will also estimate the preliminary efficacy of music interventions on reducing delirium incidence and severity.

Trial registration

ClinicalTrials.gov, Identifier: NCT03095443. Registered on 23 March 2017.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2324-6) contains supplementary material, which is available to authorized users.

A randomised trial of peri-operative positive airway pressure for postoperative delirium in patients at risk for obstructive sleep apnoea after regional anaesthesia with sedation or general anaesthesia for joint arthroplasty

Previous pilot work has established an association between obstructive sleep apnoea and the development of acute postoperative delirium , but it remains unclear to what extent this risk factor is modifiable in the 'real world' peri-operative setting. In a single-blind randomised controlled trial, 135 elderly surgical patients at risk for obstructive sleep apnoea were randomly assigned to receive peri-operative continuous positive airway pressure (CPAP) or routine care. Of the 114 patients who completed the study, 21 (18.4%) experienced delirium. Delirium was equally common in both groups: 21% (12 of 58 subjects) in the CPAP group and 16% (9 of 56 subjects) in the routine care group (OR = 1.36 [95%CI 0.52-3.54], p = 0.53). Delirious subjects were slightly older - mean (SD) age 68.9 (10.7) vs. 64.9 (8.2), p = 0.07 - but had nearly identical pre-operative STOP-Bang scores (4.19 (1.1) versus 4.27 (1.3), p = 0.79). Subjects in the CPAP group used their devices for a median (IQR [range]) of 3 (0.25-5 [0-12]) nights pre-operatively (2.9 (0.1-4.8 [0.0-12.7]) hours per night) and 1 (0-2 [0-2]) nights postoperatively (1.4 (0.0-5.1 [0.0-11.6]) hours per night). Among the CPAP subjects, the residual pre-operative apnoea-hypopnea index had a significant effect on delirium severity (p = 0.0002). Although we confirm that apnoea is associated with postoperative delirium, we did not find that providing a short-course of auto-titrating CPAP affected its likelihood or severity. Voluntary adherence to CPAP is particularly poor during the initiation of therapy.

Association between Serum IGF-I levels and Postoperative Delirium in Elderly Subjects Undergoing Elective Knee Arthroplasty

Evidence is mixed for an association between serum insulin-like growth factor-I (IGF-I) levels and postoperative delirium (POD). The current study assessed preoperative serum IGF-I levels as a predictor of incident delirium in non-demented elderly elective knee arthroplasty patients. Preoperative serum levels of total IGF-I were measured using a commercially available Human IGF-I ELISA kit. POD incidence and severity were determined using DSM-IV criteria and the Delirium Rating Scale-Revised-98 (DRS-R98), respectively. Median IGF-I levels in delirious (62.6 ng/ml) and non-delirious groups (65.9 ng/ml) were not significantly different (p = 0.141). The ratio (95% CI) of geometric means, D/ND, was 0.86 (0.70, 1.06). The Hodges-Lehmann median difference estimate was 7.23 ng/mL with 95% confidence interval (−2.32, 19.9). In multivariate logistic regression analysis IGF-I level was not a significant predictor of incident POD after correcting for medical comorbidities. IGF-I levels did not correlate with DRS-R98 scores for delirium severity. In conclusion, we report no evidence of association between serum IGF-I levels and incidence of POD, although the sample size was inadequate for a conclusive study. Further efforts to investigate IGF-I as a delirium risk factor in elderly should address comorbidities and confounders that influence IGF-I levels.

Sleep-disordered breathing in dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is the second most common form of dementia, and it is very frequently associated with changes in sleep patterns. To date, the literature has focused mainly on REM sleep behavior as the most prominent sleep disorder in DLB while little is known about the prevalence and the impact of sleep-disordered breathing (SDB) in DLB. Clinicians should be aware that the clinical diagnosis of SDB in DLB is difficult to establish and that the risk of overlooking SDB in patients with DLB is substantial. Polysomnographic sleep investigations may therefore be advisable in patients with DLB in order to objectify their sleep respiratory patterns. The available literature data on this topic, which are very limited and based on small case series, indicate that SDB occurs in 34.8 to 60% of patients with DLB. SDB can be hypothesized to coexist with other sleep-related disorders in an interactive loop: SDB alters sleep continuity, which can in turn facilitate nocturnal and daytime vigilance-dependent phenomena. There is an absolute need for prospective, preferably multi-center, controlled trials to establish whether, and to what extent, SDB might affect neuropsychological performances in patients with DLB and whether its treatment can improve residual daytime functioning in these patients.

Sleep disorders and acute nocturnal delirium in the elderly: a comorbidity not to be overlooked

Delirium is a disturbance of consciousness and cognition that results in a confusional state. It tends to fluctuate in intensity and is often observed in older patients. Sleep is a window of vulnerability for the occurrence of delirium and sleep disorders can play a role in its appearance. In particular, delirious episodes have been associated with obstructive sleep apnoea syndrome, which is reported to be frequent in the elderly. Hereby, we present a case-report documenting the sudden onset of a confusional state triggered by obstructive sleep apnoea-induced arousal, together with a review of the literature on the topic. We emphasise that, among the many pathogenic factors implicated in delirium, it is worth considering the possible link between nocturnal delirium and the occurrence of impaired arousals. Indeed, the complex confusional manifestations of delirium could be due, in part, to persistence of dysfunctional sleep activity resulting in an inability to sustain full arousal during behavioural wakefulness. Arousals can be triggered by sleep disturbances or other medical conditions. Clinicians should be aware that older patients may present disordered sleep patterns, and make investigation of sleep patterns and disorders potentially affecting sleep continuity a key part of their clinical workup, especially in the presence of cognitive comorbidities. Correct diagnosis and optimal treatment of sleep disorders and disrupted sleep can have a significant impact in the elderly, improving sleep quality and reducing the occurrence of abnormal sleep-related behaviours.