Sleep-disordered breathing and 24-hour blood pressure pattern among older adults

Sleep apnea and autonomic dysfunction in patients with dementia

Sleep apnea is common sleep disorder that is associated with an is an increase in risk of many health conditions, including systemic hypertension, stroke, atrial fibrillation, and heart failure. The predominant underlying pathophysiological mechanism for elevated risk of these conditions in patients with sleep apnea is thought to involve autonomic dysfunction in the form of sympathetic overactivity. Autonomic dysfunction is also associated with several neurodegenerative disorders and sleep apnea, in turn, has been shown to be associated with an increased risk of development of mild cognitive impairment and various types of dementia. Rapid eye movement sleep behavior disorder, which is also associated with an increased risk of alpha synucleiopathy-related dementia, is also linked with autonomic dysfunction. In this article we explore the relationship between sleep apnea, autonomic dysfunction, rapid eye movement sleep behavior disorder and dementia. This article describes the various autonomic dysfunction that are thought to occur in the context of sleep apnea. And illustrate the mechanisms by which sleep apnea, through its impact on autonomic dysfunction could potentially result in dementia. We also review the evidence examining the impact of treatment of sleep apnea on autonomic dysfunction and cognitive outcomes.

Obstructive Sleep apnea and cardiovascular events in Elderly Patients

INTRODUCTION

In recent decades, life expectancy has increased considerably. The cardiovascular effects of Obstructive Sleep Apnea (OSA) in the elderly lead to patient disability and high resource consumption. Intermittent nocturnal hypoxia leads to hemodynamic stress and adrenergic activation, which promotes cardiovascular disease. However, chronic intermittent hypoxia may protect elderly patients from cardiovascular events (CVE) due to biological adaptation.

AREAS COVERED

OSA patients are at increased risk of cardiovascular events. The severity of OSA increases cardiovascular risk, and this association also exists in the elderly. This article reviews the association between OSA, CPAP treatment, and CVE, particularly stroke and coronary heart disease (CHD), in the elderly. MEDLINE and the Cochrane Collaboration databases were searched from inception to July 2021.

EXPERT COMMENTARY

Although a positive association between OSA and the incidence of cardiovascular disease in the elderly has been established, the role of sleep apnea in certain cardiovascular events remains controversial. Most authors agree that untreated OSA is a risk factor for stroke or worse stroke prognosis. However, the association between OSA and CHD is usually less pronounced than between OSA and stroke, especially in the elderly.

Machine learning-based preoperative datamining can predict the therapeutic outcome of sleep surgery in OSA subjects

Increasing recognition of anatomical obstruction has resulted in a large variety of sleep surgeries to improve anatomic collapse of obstructive sleep apnea (OSA) and the prediction of whether sleep surgery will have successful outcome is very important. The aim of this study is to assess a machine learning-based clinical model that predict the success rate of sleep surgery in OSA subjects. The predicted success rate from machine learning and the predicted subjective surgical outcome from the physician were compared with the actual success rate in 163 male dominated-OSA subjects. Predicted success rate of sleep surgery from machine learning models based on sleep parameters and endoscopic findings of upper airway demonstrated higher accuracy than subjective predicted value of sleep surgeon. The gradient boosting model showed the best performance to predict the surgical success that is evaluated by pre- and post-operative polysomnography or home sleep apnea testing among the logistic regression and three machine learning models, and the accuracy of gradient boosting model (0.708) was significantly higher than logistic regression model (0.542). Our data demonstrate that the data mining-driven prediction such as gradient boosting exhibited higher accuracy for prediction of surgical outcome and we can provide accurate information on surgical outcomes before surgery to OSA subjects using machine learning models.

Prevalence of high risk obstructive sleep apnoea by Berlin questionnaire in patients with hypertension: study from a tertiary care hospital

Background

Obstructive Sleep Apnoea (OSA), a condition characterized by a complete or partial cessation of airflow during sleep, can cause various cardiovascular disorders including hypertension. The aim of the study was to determine the prevalence of OSA in patients with hypertension.

Methods

A cross-sectional prospective cohort study of 504 patients with hypertension was undertaken at a tertiary care hospital of India for a period of 6 months. OSA was evaluated using the Berlin questionnaire while the daytime sleepiness was determined using Epworth Sleepiness Scale. Data analysis was done using SPSS v. 20.

Results

High risk of OSA was identified in 120 (23.8%) patients and the prevalence of sleepiness (Epworth Sleepiness score >16) was found to be 32.5% (95% CI, p < 0.001) in these patients. The mean neck circumference, waist circumference and waist-to-hip ratio for high-risk OSA group were 37.41 ± 3.396 cm, 105.90 ± 11.28 cm and 1.01 ± 0.065 respectively while for the low-risk group, these parameters were 35.45 ± 2.652 cm, 98.75 ± 10.87 cm and 0.99 ± 0.080 respectively (95% CI, p<0.001). The mean blood pressure (BP) ≥133.52/84.37 mmHg was recorded in patients with a high risk of OSA (95% CI, P < 0.05), and resistant hypertension (3.3%) was significantly associated with the risk of OSA (95% CI, P < 0.05).

Conclusion

In the tertiary health care setting, the prevalence of high-risk of OSA in patients with hypertension is high. Screening for OSA should be a part of the hypertensive medical investigation and patients may benefit from a proper evaluation of OSA.

Quantification of Nocturnal Blood Pressure Oscillations Induced by Sleep Disordered Breathing

We present an approach to quantifying nocturnal blood pressure (BP) variations that are elicited by sleep disordered breathing (SDB). A sample-by-sample aggregation of the dynamic BP variations during normal breathing and BP oscillations prompted by apnea episodes is performed. This approach facilitates visualization and analysis of BP oscillations. Preliminary results from analysis of a full night study of 7 SDB subjects (5 Male 2 Female, 52±5.6 yrs., Body Mass Index 36.4±7.4 kg/m², Apnea-Hypopnea Index 69.1±26.8) are presented. Aggregate trajectory and quantitative values for changes in systolic blood pressure (SBP) and diastolic blood pressure (DBP) concomitant with obstructive apnea episodes are presented. The results show 19.4 mmHg (15.3%) surge in SBP and 9.4 mmHg (13.6%) surge in DBP compared to their respective values during normal breathing (p<0.05). Further, the peak of the surge in SBP and DBP occurred about 9s and 7s, respectively, post the end of apnea events. The return of SBP and DBP to baseline values displays a decaying oscillatory pattern.

Apnea in Older Adults

Sleep-disordered breathing (SDB) is a highly prevalent chronic disease in older adults. A growing body of evidence demonstrates that SDB in older adults is linked to many adverse cardiovascular, neurocognitive, and metabolic sequelae. However, several unanswered questions remain regarding the diagnosis, consequences, and treatment of SDB in older adults. This review presents the current evidence pertaining to the management of SDB in older adults and identifies crucial gaps in knowledge that need further investigation.

Sleep, death, and the heart

Obstructive and central sleep apnea have been associated with increased risk of adverse cardiovascular events and mortality. Sympathetic dysregulation occurring as a result of the respiratory disturbance is thought to play a role in this increased risk. Sleep apnea increases the risk of arrhythmias, myocardial ischemia/infarction, stroke, and heart failure, all of which may increase mortality risk. A higher incidence of nocturnal arrhythmias, cardiac ischemia, and sudden death has been noted in subjects with sleep-disordered breathing (SDB). In this review, the association between SDB and each of these conditions is discussed, as well as the potential mechanisms underlying these risks and the effects of treatment of SDB. Particular emphasis is placed on the relationship between SDB and nocturnal atrial and ventricular arrhythmias, myocardial ischemia/infarction and sudden death.

Obstructive sleep apnoea in the elderly: role of continuous positive airway pressure treatment

Almost all the information about the effect of continuous positive airway pressure (CPAP) in patients with obstructive sleep apnoea (OSA) comes from clinical trials involving only middle-aged patients. The objective of this study was to assess the effect of CPAP treatment in elderly patients with severe OSA on clinical, quality-of-life and neurocognitive spheres. We performed an open-label, randomised, multicentre clinical trial in a consecutive clinical cohort of 224 elderly (≥70 years old) patients with confirmed severe OSA (apnoea-hypopnea index ≥30) randomised to receive CPAP (n=115) or no CPAP (n=109) for 3 months. A sleep study was performed by either full polysomnography or respiratory polygraphy. CPAP titration was performed by an autoCPAP device. The primary endpoint was quality of life (Quebec Sleep Questionnaire) and secondary endpoints included sleep-related symptoms, presence of anxiety/depression, office-based blood pressure and some neurocognitive tests. The mean±sd age was 75.5±3.9 years. The CPAP group achieved a greater improvement in all quality-of-life domains (p<0.001; effect size: 0.41-0.98), sleep-related symptoms (p<0.001; effect size 0.31-0.91) as well as anxiety (p=0.016; effect size 0.51) and depression (p<0.001; effect size: 0.28) indexes and some neurocognitive tests (digit symbol test (p=0.047; effect size: 0.20) and Trail Making Test A (p=0.029; effect size: 0.44)) in an intention-to-treat analysis. In conclusion, CPAP treatment resulted in an improvement in quality of life, sleep-related symptoms, anxiety and depression indexes and some neurocognitive aspects in elderly people with severe OSA.

Chemoreflexes, sleep apnea, and sympathetic dysregulation

Obstructive sleep apnea (OSA) and hypertension are closely linked conditions. Disordered breathing events in OSA are characterized by increasing efforts against an occluded airway while asleep, resulting in a marked sympathetic response. This is predominantly due to hypoxemia activating the chemoreflexes, resulting in reflex increases in sympathetic neural outflow. In addition, apnea - and the consequent lack of inhibition of the sympathetic system that occurs with lung inflation during normal breathing - potentiates central sympathetic outflow. Sympathetic activation persists into the daytime, and is thought to contribute to hypertension and other adverse cardiovascular outcomes. This review discusses chemoreflex physiology and sympathetic modulation during normal sleep, as well as the sympathetic dysregulation seen in OSA, its extension into wakefulness, and changes after treatment. Evidence supporting the role of the peripheral chemoreflex in the sympathetic dysregulation seen in OSA, including in the context of comorbid obesity, metabolic syndrome, and systemic hypertension, is reviewed. Finally, alterations in cardiovascular variability and other potential mechanisms that may play a role in the autonomic imbalance in OSA are also discussed.

Impacts of comorbidities on the association between arterial stiffness and obstructive sleep apnea in the elderly

BACKGROUND

Although the impact of obstructive sleep apnea (OSA) on cardiovascular risk is reasonably well established in middle-aged patients, the debate persists as to whether OSA also increases this risk in the elderly. Arterial stiffness has been used as an early independent predictor of cardiovascular risk.

STUDY OBJECTIVES

We sought to determine whether OSA has significant effects on the arterial stiffness in the elderly population and evaluate the impact of comorbidities on the association between arterial stiffness and OSA.

METHODS

We performed a cross-sectional study in a university hospital. Elderly participants (≥60 years) were invited to participate in our study between November 2010 and January 2013. OSA was diagnosed using gold standard polysomnography and arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV), cardio-ankle vascular index (CAVI) and central systolic and diastolic blood pressure (cSBP and cDBP). The high-sensitivity C-reactive protein (hs-CRP) level was also measured.

RESULTS

We found no significant association between the severity of OSA and the arterial stiffness-related parameters cSBP, cDBP, baPWV, CAVI and hs-CRP. However, in patients with no comorbid medical conditions or use of medications (n = 101), we showed a modest association between OSA and arterial stiffness-related parameters and hs-CRP.

CONCLUSION

We conclude that OSA is associated with increased arterial stiffness in an otherwise healthy elderly population, although the association was obviated by comorbidities and medications perhaps due to ceiling effects.

A pilot study: portable out-of-center sleep testing as an early sleep apnea screening tool in acute ischemic stroke

INTRODUCTION

Prompt diagnosis of obstructive sleep apnea (OSA) after acute ischemic stroke (AIS) is critical for optimal clinical outcomes, but in-laboratory conventional polysomnograms (PSG) are not routinely practical. Though portable out-of-center type III cardiopulmonary sleep studies (out-of-center cardiopulmonary sleep testing [OCST]) are widely available, these studies have not been validated in patients who have recently suffered from AIS. We hypothesized that OCST in patients with AIS would yield similar results when compared to conventional PSG.

METHODS

Patients with AIS had simultaneous type III OCST and PSG studies performed within 72 hours from symptom onset. The accuracy of OCST was compared to PSG using: chi-square tests, receiver operatory characteristic curves, Bland-Altman plot, paired Student's t-test/Wilcoxon signed-rank test, and calculation of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

RESULTS

Twenty-one out of 23 subjects with AIS (age 61±9.4 years; 52% male; 58% African-American) successfully completed both studies (9% technical failure). Nearly all (95%) had Mallampati IV posterior oropharynx; the mean neck circumference was 16.8±1.6 in. and the mean body mass index (BMI) was 30±7 kg/m(2). The apnea hypopnea index (AHI) provided by OCST was similar to that provided by PSG (19.8±18.0 vs 22.0±22.7, respectively; P=0.49). On identifying subjects by OCST with an AHI ≥5 on PSG, OCST had the following parameters: sensitivity 100%, specificity 85.7%, PPV 93%, and NPV 100%. On identifying subjects with an AHI ≥15 on PSG, OCST parameters were as follows: sensitivity 100%, specificity 83.3%, PPV 81.8%, and NPV 100%. Bland-Altman plotting showed an overall diagnostic agreement between OCST and PSG modalities for an AHI cutoff >5, despite fine-grained differences in estimated AHIs.

CONCLUSION

Compared with PSG, OCST provides similar diagnostic information when run simultaneously in AIS patients. OCST is a reliable screening tool for early diagnosis of OSA in AIS patients.

Chemoreflex physiology and implications for sleep apnoea: insights from studies in humans

NEW FINDINGS

What is the topic of this review? This review summarizes chemoreflex physiology in health and disease, with specific focus on chemoreflex-mediated pathophysiology in obstructive and central sleep apnoea. What advances does it highlight? Chemoreflex mechanisms are thought to contribute significantly to the pathophysiology and adverse outcomes seen in sleep apnoea. Clinical implications of altered chemoreflex function in sleep apnoea from recent studies in humans, including cardiac arrhythmias, coronary artery disease, systolic/diastolic heart failure and sudden cardiac death are highlighted. Activation of the chemoreflex in response to hypoxaemia results in an increase in sympathetic neural outflow. This process is predominantly mediated by the peripheral chemoreceptors in the carotid bodies and is potentiated by the absence of the sympatho-inhibitory influence of ventilation during apnoea, as is seen in patients with sleep apnoea. In these patients, repetitive nocturnal hypoxaemia and apnoea elicit sympathetic activation, which may persist into wakefulness and is thought to contribute to the development of systemic hypertension and cardiac and vascular dysfunction. Chemoreflex activation could possibly lead to adverse cardiovascular outcomes, such as nocturnal myocardial infarction, systolic and/or diastolic heart failure, cardiac arrhythmias and sudden death in patients with sleep apnoea. This review summarizes chemoreflex physiology in health and disease, with specific focus on chemoreflex-mediated pathophysiology in obstructive and central sleep apnoea. Measurement of the chemoreflex response may serve as a potential avenue for individualized screening for cardiovascular disease. Whether modulation of this response in sleep apnoea may aid in the prevention and treatment of adverse cardiovascular consequences will require further study.

Distinct associations between hypertension and obstructive sleep apnea in male and female patients

Obstructive sleep apnea (OSA) is highly associated with hypertension. However, the correlation between hypertension and OSA at different levels of severity and the influence of gender on that correlation are unclear. A total of 996 patients (776 males and 190 females) with OSA were recruited. The influence of gender on the correlation between hypertension and OSA at different stratifications of severity, based on the apnea-hypopnea index (AHI), was fully evaluated together with the major health risk factors obesity, age, and diabetes. Females with OSA were significantly older on average than males with OSA. Moreover, females had milder degrees of OSA on average than the extent of severity seen in males. The proportion of females with diabetes or hypertension was higher than that of males. The proportion of males with hypertension and obesity increased significantly with OSA, and age also increased with OSA. The percentage of females with hypertension at different degrees of OSA severity was stable at about 26% in the mild, moderate, and severe OSA groups. Among females, age was increased significantly in the moderate relative to the mild OSA group. Moreover, the proportion of obese subjects was increased significantly in the severe compared with the moderate OSA group. The proportions of males and females with diabetes were not significantly different among all OSA severity groups. An ordinal multivariate logistic regression analysis confirmed that hypertension, age, and obesity were associated with OSA severity in males, whereas only age and obesity were associated with OSA severity in females. Although the proportion of subjects with hypertension was higher in females with OSA than in males with OSA, the proportion of subjects with hypertension increased as the severity of OSA increased in males but not in females.

Snoring, daytime sleepiness, and incident cardiovascular disease in the health, aging, and body composition study

OBJECTIVES

To examine the association between snoring and incident cardiovascular disease (CVD).

DESIGN SETTINGS AND PARTICIPANTS

This is a prospective study in which community dwelling older adults were evaluated at baseline, and followed up for an average of 9.9 years.

MEASUREMENTS

Data on snoring, daytime sleepiness, as well as demographic and clinical characteristics of study participants was collected at baseline, and participants were followed up every six months for an average of 9.9 years. Based on snoring and sleepiness status, 4 groups of participants were created: (1) No Snoring, No Sleepiness; (2) No Snoring, Sleepiness; (3) Snoring, No Sleepiness; (4) Snoring, Sleepiness. Incident CVD was defined as a diagnosis of myocardial infarction, angina pectoris, or congestive heart failure that resulted in overnight hospitalization during the follow-up period. Cox proportional hazard was used to estimate the risk of incident cardiovascular disease during follow-up by baseline snoring and sleepiness status.

RESULTS

A total of 2,320 participants with a mean age of 73.6 (2.9) years at baseline were included in the analysis. Fifty-two percent were women, and 58% were white. A total of 543 participants developed CVD events during the follow-up period. Participants who reported snoring associated with daytime sleepiness had significantly increased hazard ratio for CVD events (HR = 1.46 [1.03-2.08], P = 0.035) after adjusting for demographic and clinical confounding factors.

CONCLUSION

The results suggest that self-reported snoring and daytime sleepiness status are associated with an increased risk of future cardiovascular disease among older adults.

Neurocognitive correlates of nocturnal oxygen desaturation in a memory clinic population

Previous studies suggested that sleep apnea is associated with neurocognitive impairments but did not examine populations most likely to have clinically relevant impairments. Cross-sectional, retrospective analyses were performed on 108 patients (65 with mild cognitive impairment, 43 with dementia) seen in an academic medical center. Results indicated that severity of oxygen desaturation was associated with cognitive impairments in attention and executive function domains, even after controlling for age, sex, education, and depressive symptoms. Strength of associations was influenced by cardiovascular disease. Screening for nocturnal oxygen desaturation may be a useful procedure to assess for a potentially reversible cause of cognitive impairment.

Executive summary of respiratory indications for polysomnography in children: an evidence-based review

OBJECTIVE

This comprehensive, evidence-based review provides a systematic analysis of the literature regarding the validity, reliability, and clinical utility of polysomnography for characterizing breathing during sleep in children. Findings serve as the foundation of practice parameters regarding respiratory indications for polysomnography in children.

METHODS

A task force of content experts performed a systematic review of the relevant literature and graded the evidence using a standardized grading system. Two hundred forty-three evidentiary papers were reviewed, summarized, and graded. The analysis addressed the operating characteristics of polysomnography as a diagnostic procedure in children and identified strengths and limitations of polysomnography for evaluation of respiratory function during sleep.

RESULTS

The analysis documents strong face validity and content validity, moderately strong convergent validity when comparing respiratory findings with a variety of relevant independent measures, moderate-to-strong test-retest validity, and limited data supporting discriminant validity for characterizing breathing during sleep in children. The analysis documents moderate-to-strong test-retest reliability and interscorer reliability based on limited data. The data indicate particularly strong clinical utility in children with suspected sleep related breathing disorders and obesity, evolving metabolic syndrome, neurological, neurodevelopmental, or genetic disorders, and children with craniofacial syndromes. Specific consideration was given to clinical utility of polysomnography prior to adenotonsillectomy (AT) for confirmation of obstructive sleep apnea syndrome. The most relevant findings include: (1) recognition that clinical history and examination are often poor predictors of respiratory polygraphic findings, (2) preoperative polysomnography is helpful in predicting risk for perioperative complications, and (3) preoperative polysomnography is often helpful in predicting persistence of obstructive sleep apnea syndrome in patients after AT. No prospective studies were identified that address whether clinical outcome following AT for treatment of obstructive sleep apnea is improved in association with routine performance of polysomnography before surgery in otherwise healthy children. A small group of papers confirm the clinical utility of polysomnography for initiation and titration of positive airway pressure support.

CONCLUSIONS

Pediatric polysomnography shows validity, reliability, and clinical utility that is commensurate with most other routinely employed diagnostic clinical tools or procedures. Findings indicate that the "gold standard" for diagnosis of sleep related breathing disorders in children is not polysomnography alone, but rather the skillful integration of clinical and polygraphic findings by a knowledgeable sleep specialist. Future developments will provide more sophisticated methods for data collection and analysis, but integration of polysomnographic findings with the clinical evaluation will represent the fundamental diagnostic challenge for the sleep specialist.

Perioperative practical experiences in using a level 2 portable polysomnography

PURPOSE

The objective of the study is to test the hypothesis that a level 2 portable sleep device (Embletta X100) is a reliable alternative for standard PSG in surgical patients.

METHODS

After hospital ethics approvals, preoperative patients over 18 years old were recruited. The patients for validation underwent standard PSG and Embletta X100 simultaneously in a sleep laboratory before surgery. The other patients received sleep studies with Embletta X100 perioperatively. The correlation analysis and paired Student t test between variables from Embletta and from standard PSG were used to evaluate the accuracy of Embletta. The quality of PSG recordings with Embletta was summarized.

RESULT

Twenty-one patients completed sleep study on both systems; ten females and ten males, age was 54 ± 11 and BMI was 36 ± 9. There was a significant correlation between the majority of parameters from standard PSG and Embeltta X100 with manual scoring. The inter-rater agreement was substantial to perfect at different AHI cutoffs with a Kappa coefficient of 0.69 to 1. A significant correlation between standard PSG and Embletta X100 with automatic scoring was found only in AHI and a few other parameters. In 385 patients, 1,002 perioperative PSG recordings were carried out with Embletta. Of them, 889(88.7%) were technically good and 90(9%) technically acceptable. Only 23 (2.3%) PSG recordings failed.

CONCLUSION

Embletta X100, installed by a well-trained sleep technician, is a good alternative when standard PSG was not available or impractical. Manual scoring by a certified PSG technologist is the key for reliable results.

Sleep-disordered breathing and frailty in the Cardiovascular Health Study Cohort

Sleep-disordered breathing (SDB) is associated with pathophysiology that may influence the development and progression of frailty. Using data collected in 1995-1996, the authors explored the relation between SDB and components of frailty among 1,042 participants of the Cardiovascular Health Study. Diagnosis of SDB was based on the results of overnight polysomnography, and severe SDB was defined as an apnea-hypopnea index of >30 per hour of sleep. Slow walking speed, low grip strength, exhaustion, low physical activity, and unexplained weight loss were referred to as frailty indicator variables. There were 584 (56%) female and 458 (44%) male participants, and the mean age was 77 (standard deviation, 4) years. There was independent association between severe SDB and 1 or more frailty indicator variables (adjusted odds ratio = 4.85, 95% confidence interval: 1.40, 16.78), slow walking speed (adjusted odds ratio = 2.67, 95% confidence interval: 1.04, 6.84), and low grip strength (adjusted odds ratio = 3.29, 95% confidence interval: 1.36, 7.96) among female study participants. The finding of an independent association between SDB and frailty indicator variables among older women could have important implications in interventions aimed at preventing or delaying the progression of frailty.