Sleep-related breathing disorders and cardiovascular disease

Economic evaluation of telemonitoring as a follow-up approach for patients with obstructive sleep apnea syndrome starting treatment with continuous positive airway pressure

Telemonitoring of obstructive sleep apnea patients is increasingly being adopted though its cost-effectiveness evidence base is scanty. This study investigated whether telemonitoring is a cost-effective strategy compared with the standard follow-up in patients with obstructive sleep apnea who are starting continuous positive airway pressure treatment. In total, 167 obstructive sleep apnea patients were randomised into telemonitoring (n = 79) or standard follow-up (n = 88), initiated continuous positive airway pressure treatment, and were followed up for 6 months. The frequencies of healthcare contacts, related costs (in USD 2021 prices), treatment effect and compliance were compared between the follow-up approaches using generalised linear models. The cost effectiveness analysis was conducted from a healthcare perspective and the results presented as cost per avoided extra clinic visit. Additionally, patient satisfaction between the two approaches was explored. The analysis showed no baseline differences. At follow-up, there was no significant difference in treatment compliance, and the mean residual apnea-hypoapnea index. There was no difference in total visits, adjusted incidence rate ratio 0.87 (0.72-1.06). Participants in the telemonitoring arm made eight times more telephone visits, 8.10 (5.04-13.84), and about 73% fewer physical healthcare visits 0.27 (0.20-0.36). This translated into significantly lower total costs for the telemonitoring approach compared with standard follow-up, -192 USD (-346 to -41). The form of follow-up seemed to have no impact on the extent of patient satisfaction. These results demonstrate the telemonitoring of patients with obstructive sleep apnea initiating continuous positive airway pressure treatment as a cost saving strategy and can be argued as a potential worthy investment.

Development and validation of a scale for the assessment of the knowledge-attitude-practice of parents towards children snoring

BACKGROUND

Children Snoring is a common childhood disorder that affects the growth and development of children and is detrimental to their health. Increasing awareness of Children Snoring among parents is important.

AIM

To develop the Knowledge-Attitude-Practice of Parents towards Children Snoring Scale and test the reliability and validity of the scale.

METHODS

The development of the tool was divided into two phases involving 1257 parents from China. In the first phase, an initial project bank was created through a literature review. This was followed by a Delphi expert consultation, group discussion and pre-survey. The second stage screened the items and conducted an exploratory factor analysis, then conducted a confirmatory factor analysis and tested for reliability and validity.

RESULTS

Support was found for the 25-item Knowledge-Attitude-Practice toward Children Snoring scale. Exploratory and confirmatory factor analyses provide support for four subscales: (parental basic cognition toward Children Snoring; parents' perception of complications of Children Snoring; parents' attitude towards Children Snoring; parents' concern and prevention of Children Snoring). Internal consistency for the total scale was high (Cronbach's α = 0.93). The intraclass correlation coefficient of test-retest reliability was 0.92 (95%CI: 0.85 to 0.95), which provided support for the stability of the scale.

CONCLUSION

The Knowledge-Attitude-Practice of Parents towards Children Snoring scale shows promise as a measure that may be used by medical workers and community children's health managers.

Increased Levels of VCAM-1 in Patients with High Cardiovascular Risk and Obstructive Sleep Apnea Syndrome

(1) Background: Although obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity, the link between OSA and cardiovascular disease (CVD) is not completely elucidated. Thus, we aim to assess cardiovascular risk (CVR) using SCORE 2 and SCORE 2 for older persons (SCORE 2OP), and to evaluate the association between the endothelial biomarkers VCAM-1, ICAM-1, epicardial fat, and sleep study parameters in order to improve current clinical practices and better understand the short-and long-term CVRs in OSA patients. (2) Methods: 80 OSA patients and 37 healthy volunteers were enrolled in the study. SCORE2 and SCORE 2 OP regional risk charts (validated algorithms to predict the 10-year risk of first-onset CVD) were used for the analysis of CVR. Two-dimensional echocardiography was performed on all patients and epicardial fat thickness was measured. VCAM-1 and ICAM-1 serum levels were assessed in all patients. (3) Results: OSA patients were classified as being at high CVR, regardless of the type of score achieved. Increased EFT was observed in the OSA group. VCAM-1 was associated with a high CVR in OSA patients, but no significant correlation was observed between adhesion molecules and epicardial fat thickness. (4) Conclusions: OSA patients have a high CVR according to the SCORE 2 and SCORE 2OP risk scores. VCAM-1 may be associated with a high CVR in OSA patients. Extending conventional risk stratification scores by adding other potential biomarkers improves the risk stratification and guide treatment eligibility for CVD prevention in the OSA population.

Anthropometric Determinants of Autonomic Control in Obstructive Sleep Apnea: A Large-Scale Study

OBJECTIVE

Autonomic dysfunction is an independent risk factor for cardiovascular disease (CVD). Both obesity and obstructive sleep apnea (OSA) are associated with heart rate variability (HRV) (a hall marker of sympathetic arousal) and increased risk of CVD. This study aims to investigate whether anthropometric parameters could predict reduced HRV in adult OSA during wakefulness.

STUDY DESIGN

Cross-sectional study.

SETTING

Sleep center of Shanghai Jiao Tong University Affiliated Sixth Hospital from 2012 to 2017.

METHODS

Total of 2134 subjects (503 non-OSA and 1631 OSA) were included. Anthropometric parameters were recorded. HRV was recorded during a 5-minute wakefulness period and analyzed by using time-domain method and frequency-domain method. Multiple step-wise linear regressions were performed to determine significant predictors of HRV with and without adjustments. Multiplicative interactions between gender, OSA, and obesity on HRV were also determined and evaluated.

RESULTS

Waist circumference (WC) was significant negative determinant of root mean square of successive NN intervals (β = -.116, p < .001) and high-frequency power (β = -.155, p < .001). Age was the strongest determining factor of HRV. Significant multiplicative interactions between obesity and OSA on HRV, gender, and obesity on cardiovascular parameters were observed.

CONCLUSION

Anthropometric parameters could predict reduced HRV during wakefulness in patients with OSA, especially WC was the strongest influenceable factor. Obesity and OSA had significant multiplicative interaction on HRV. Gender and obesity had significant multiplicative interaction on cardiovascular parameters. Early intervention for obesity, especially centripetal obesity, may improve reduction of autonomic function and risk of CVD.

Heart Rate Variability as a Surrogate Marker of Severe Chronic Coronary Syndrome in Patients with Obstructive Sleep Apnea

BACKGROUND AND OBJECTIVES

Obstructive sleep apnea (OSA) is a known risk factor for chronic coronary syndrome (CCS). CCS and OSA are separately associated with significant changes in heart rate variability (HRV). In this proof-of-concept study, we tested whether HRV values are significantly different between OSA patients with concomitant severe CCS, and OSA patients without known CCS.

MATERIAL AND METHODS

The study comprised a retrospective assessment of the historical and raw polysomnography (PSG) data of 32 patients who presented to a tertiary university hospital with clinical complaints of OSA. A total of 16 patients (four females, mean age 62.94 ± 2.74 years, mean body mass index (BMI) 31.93 ± 1.65 kg/m2) with OSA (median apnea-hypopnea index (AHI) 39.1 (30.5-70.6)/h) and severe CCS were compared to 16 patients (four females, mean age 62.35 ± 2.06 years, mean BMI 32.19 ± 1.07 kg/m2) with OSA (median AHI 40 (30.6-44.5)/h) but without severe CCS. The short-long-term HRV (in msec) was calculated based on the data of a single-lead electrocardiogram (ECG) provided by one full-night PSG, using the standard deviation of the NN, normal-to-normal intervals (SDNN) and the heart rate variability triangular index (HRVI) methods, and compared between the two groups.

RESULTS

A significant reduction (p < 0.05) in both SDNN and HRVI was found in the OSA group with CCS compared to the OSA group without CCS.

CONCLUSIONS

Severe CCS has a significant impact on short-long-term HRV in OSA patients. Further studies in OSA patients with less-severe CCS may shed more light onto the involved mechanistic processes. If confirmed in future larger studies, this physiologic metric has the potential to provide a robust surrogate marker of severe CCS in OSA patients.

Association of Heart Rate Variability with Obstructive Sleep Apnea in Adults

Background and Objectives: Heart rate variability (HRV) analysis is a noninvasive method used to examine autonomic system function, and the clinical applications of HRV analysis have been well documented. The aim of this study is to investigate the association between HRV and the apnea–hypopnea index (AHI) in patients referred for polysomnography (PSG) for obstructive sleep apnea (OSA) diagnosis. Materials and Methods: Patients underwent whole-night PSG. Data on nocturnal HRV and AHI were analyzed. We determined the correlation of time- and frequency-domain parameters of HRV with the AHI. Results: A total of 62 participants (50 men and 12 women) were enrolled. The mean age, body mass index (BMI), neck circumference, and AHI score of the patients were 44.4 ± 11.5 years, 28.7 ± 5.2, 40.2 ± 4.8 cm, and 32.1 ± 27.0, respectively. The log root mean square of successive differences between normal heartbeats (RMSSD) were negatively correlated with BMI (p = 0.034) and neck circumference (p = 0.003). The log absolute power of the low-frequency band over high-frequency band (LF/HF) ratio was positively correlated with the AHI (p = 0.006). A higher log LF/HF power ratio (β = 5.01, p = 0.029) and BMI (β = 2.20, p < 0.001) were associated with a higher AHI value in multiple linear regression analysis. Conclusions: A higher log LF/HF power ratio and BMI were positively and significantly associated with the AHI during whole-night PSG in adult patients.

Effects of CPAP treatment on electroencephalographic activity in patients with obstructive sleep apnea syndrome during deep sleep: Preliminary findings of a cross-sectional study

Study objectives: To investigate whether electroencephalographic (EEG) activities during non-rapid eye movement sleep stage 3 (N3) in obstructive sleep apnea syndrome (OSAS) patients were changed with continuous positive airway pressure (CPAP) treatment.Methods: A cross-sectional study of EEG activity during N3 sleep was conducted in 15 patients with moderate to severe OSAS without and with CPAP treatment compared to 15 normal controls. The amplitude, and absolute and relative power of delta, theta, alpha and beta waves as well as the absolute power ratio of slow to fast EEG waves (i.e., absolute power of delta and theta waves/absolute power of alpha and beta waves) and the spectral power density of 0-30 Hz EEG activities were analyzed.Results: CPAP significantly increased N3 sleep, the absolute and relative powers, amplitudes of delta and theta waves, and absolute power ratio of slow to fast EEG waves, but decreased relative alpha and beta powers during N3 sleep. However, there were no significant differences in those parameters between the OSAS patients with CPAP treatment and normal controls.Conclusions: CPAP prolongs N3 sleep and increases the power and amplitude of slow EEG waves during N3 sleep, which indicates an improvement in sleep quality and further provides evidence for recommendation of CPAP treatment for OSAS patients.

Obstructive Sleep Apnoea Syndrome Screening Through Wrist-Worn Smartbands: A Machine-Learning Approach

Purpose

A large portion of the adult population is thought to suffer from obstructive sleep apnoea syndrome (OSAS), a sleep-related breathing disorder associated with increased morbidity and mortality. International guidelines include the polysomnography and the cardiorespiratory monitoring (CRM) as diagnostic tools for OSAS, but they are unfit for a large-scale screening, given their invasiveness, high cost and lengthy process of scoring. Current screening methods are based on self-reported questionnaires that suffer from lack of objectivity. On the contrary, commercial smartbands are wearable devices capable of collecting accelerometric and photoplethysmographic data in a user-friendly and objective way. We questioned whether machine-learning (ML) classifiers trained on data collected through these wearable devices would help predict OSAS severity.

Patients and Methods

Each of the patients (n = 78, mean age ± SD: 57.2 ± 12.9 years; 30 females) underwent CRM and concurrently wore a commercial wrist smartband. CRM's traces were scored, and OSAS severity was reported as apnoea hypopnoea index (AHI). We trained three pairs of classifiers to make the following prediction: AHI <5 vs AHI ≥5, AHI <15 vs AHI ≥15, and AHI <30 vs AHI ≥30.

Results

According to the Matthews correlation coefficient (MCC), the proposed algorithms reached an overall good correlation with the ground truth (CRM) for AHI <5 vs AHI ≥5 (MCC: 0.4) and AHI <30 vs AHI ≥30 (MCC: 0.3) classifications. AHI <5 vs AHI ≥5 and AHI <30 vs AHI ≥30 classifiers' sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV) and diagnostic odds ratio (DOR) are comparable with the STOP-Bang questionnaire, an established OSAS screening tool.

Conclusion

Machine learning algorithms showed an overall good performance. Unlike questionnaires, these are based on objectively collected data. Furthermore, these commercial devices are widely distributed in the general population. The aforementioned advantages of machine-learning algorithms applied to smartbands' data over questionnaires lead to the conclusion that they could serve a population-scale screening for OSAS.

Difficulty of falling asleep and non-high-density lipoprotein cholesterol level among Canadian older adults: a cross-sectional analysis of the Canadian Longitudinal Study for Aging baseline data

OBJECTIVE

To examine whether difficulty of falling asleep (DoFA) is associated with non-high-density lipoprotein cholesterol (non-HDL-C) level among Canadian older adults.

METHODS

26,954 individuals aged 45–85 years from the baseline data of the Canadian Longitudinal Study for Aging were included in this study. DoFA was categorized into five groups by answer to the question “Over the last month, how often did it take you more than 30 min to fall asleep?” Response options are “Never, < 1 time/week, 1−2 times/week, 3−5 times/week, or 6−7 times/week”. Non-HDL-C, the difference of total cholesterol and HDL-C, were categorized into five categories based on these cut-offs (< 2.6 mmol/L, 2.6−3.7 mmol/L, 3.7−4.8 mmol/L, 4.8−5.7 mmol/L, and ≥ 5.7 mmol/L). Ordinal logistic regression (logit link) continuation ratio models were used to estimate the odds of higher non-HDL-C levels for DoFA status. Adjusted means of non-HDL-C by DoFA status were estimated by general linear models. All analyses were sex separately using analytic weights to ensure generalizability.

RESULTS

The proportions of DoFA in five categories were 41.6%, 25.7%, 13.6%, 9.4%, 9.7% for females and 52.9%, 24.9%, 10.5%, 6.1%, 5.6% for males, respectively. After adjustment of demographical and other covariates (such as depression, comorbidity, sleeping hour, etc.) compared to those who reported never having DoFA, the ORs (95% CIs) of higher levels of non-HDL-C for those whose DoFA status in < 1 time/week, 1−2 times/week, 3−5 times/week, and 6−7 times/week were 1.12 (1.05−1.21), 1.09 (0.99−1.18), 1.20 (1.09−1.33), 1.29 (1.17−1.43) in females and 1.05 (0.98−1.13), 0.95 (0.87−1.05), 1.21 (1.08−1.37), 0.97 (0.85−1.09) in males, respectively. The adjusted means of non-HDL-C among the five DoFA status were 3.68 mmol/L, 3.73 mmol/L, 3.74 mmol/L, 3.82 mmol/L, 3.84 mmol/L for females and 3.54 mmol/L, 3.58 mmol/L, 3.51 mmol/L, 3.69 mmol/L, 3.54 mmol/L for males, respectively.

CONCLUSIONS

The results of this study have identified a risk association pattern between DoFA status and non-HDL-C levels in females but not in males. Further research is needed to confirm these findings.

Effects of nighttime sleep duration and sex on the association between siesta and hypertension

OBJECTIVE

To examine the association between siesta and hypertension by sex and nighttime sleep duration among Chinese adults aged ≥35 years in Yinzhou, Ningbo City.

METHODS

All data were obtained from physical examinations and structured questionnaires. A total of 44, 652 participants were included. Logistic regression models were applied to calculate odds ratios and 95% confidence intervals for the association between siesta and hypertension.

RESULTS

When compared with no siesta, siesta durations of 60∼89 min (OR = 1.10, 95% CI:1.04-1.17) and ≥90 min (OR = 1.21, 95% CI:1.08-1.36) were associated with higher risk of hypertension in women. But no significant association was observed in men. Siesta durations of 30∼59 min (OR = 1.09, 95% CI:1.00-1.19) and 60-89 min (OR = 1.10, 95% CI:1.05-1.16) were associated with hypertension in people with 6∼8 h sleep, and this association appeared seemingly stronger with ≥90 min siesta either in short (<6 h) sleepers (OR = 1.20, 95% CI: 0.99-1.47) or in long (>8 h) sleepers (OR = 1.29, 95% CI: 1.00-1.68). However, in short sleepers, 60∼89 min siesta seemed to be associated with decreased risk of hypertension (OR = 0.95, 95% CI: 0.85-1.06); while in long sleepers, the same range of siesta seemed to be associated with increased risk of hypertension (OR = 1.11, 95% CI: 0.93-1.34).

CONCLUSION

Long siesta was associated with increased risk of hypertension in women but not in men. Not too long siesta may be related to decreased risk of hypertension in short sleepers but not in people with adequate or even long sleep. These findings warrant further examination with prospective studies and laboratory investigations.

Sleep disturbance in heart failure: A concept analysis

AIM

This concept analysis aims to analyze the concept of sleep disturbance (SD) in the context of heart failure (HF) to guide the development of a clearly defined definition.

BACKGROUND

The term "sleep disturbance" has been used in the literature to describe sleep problems and sleep disorders among individuals with HF. Environmental, physical, psychological, behavioral, and developmental factors complicate the phenomenon of SD in HF.

DESIGN

Walker and Avant's method was used for this concept analysis.

DATA SOURCE

Published literature from 2000 to 2020 was identified from electronic health profession-related databases. The current definition and usages of SD were abstracted from empirical work and electronic databases.

REVIEW METHODS

A focused review of abstracts and full text relating to SD in HF was performed. Studies featuring original data and peer-reviewed articles written in English were included to investigate the multifactorial contextual meaning of the concept.

RESULTS

SD in HF can be described as a condition in which individuals experience difficulty initiating and maintaining sleep, and difficulty continuing or resuming sleep due to frequent nocturnal arousals due to HF symptoms, sleep-disordered breathing, insomnia, and psychological burdens.

CONCLUSIONS

To evaluate SD in HF, clinicians must examine the underlying causes to provide the contextual meaning of the concept. A clearly defined and distinguishable concept of SD in HF provides a possibility for accurate measurements of sleep quality, exploring interventions, and evaluating outcomes.

Heart rate variability and obstructive sleep apnea: Current perspectives and novel technologies

Obstructive sleep apnea (OSA) is a highly prevalent condition, resulting in recurrent hypoxic events, sleep arousal, and daytime sleepiness. Patients with OSA are at an increased risk of cardiovascular morbidity and mortality. The mechanisms underlying the development of cardiovascular disease in OSA are multifactorial and cause a cascade of events. The primary contributing factor is sympathetic overactivity. Heart rate variability (HRV) can be used to evaluate shifts in the autonomic nervous system, during sleep and in response to treatment in patients with OSA. Newer technologies are aimed at improving HRV analysis to accelerate processing time, improve the diagnosis of OSA, and detection of cardiovascular risk. The present review will present contemporary understandings and uses for HRV, specifically in the realms of physiology, technology, and clinical management.

Psychoactive drug and medication use among patients referred to a tertiary sleep laboratory population

Psychoactive drugs including alcohol, caffeine, and prescription medications are commonly consumed to alter sleep/wake states, however the prevalence and impact of these drugs among populations seeking assessment from sleep physicians are unknown. We investigated the prevalence of commonly used drugs (alcohol and caffeine), and medications in a population (N=120; 50 females and 70 males) attending a tertiary sleep clinic for diagnostic polysomnography (PSG) assessment. In addition to objective sleep assessment, participants completed questionnaires assessing sleep quality (Pittsburgh Sleep Quality Index, PSQI), daytime sleepiness (Epworth Sleepiness Scale, ESS), depression and anxiety (Hospital Anxiety and Depression Scale, HADS), alcohol use (Alcohol Use Disorders Identification Test, AUDIT), caffeine and medication use, as well as their experience of adverse events (motor vehicle accidents and near-miss crashes). Caffeine was consumed by 90% of the population and was associated with a reduction in excessive sleepiness symptomology; while high AUDIT scores were associated with increased near-miss crashes. Polypharmacy was common, with a greater number of medications associated with poorer sleep quality, and changes in sleep architecture. This study maps commonly used drugs in those attending a tertiary sleep clinic, and demonstrates associations between drug use and sleep outcomes assessed objectively and subjectively.

SENP1-mediated NEMO de-SUMOylation inhibits intermittent hypoxia induced inflammatory response of microglia in vitro

Among the seven small ubiquitin-like modifier (SUMO)-specific proteases (SENPs), our previous work showed that SENP1 suppressed nuclear factor kappa B (NF-κB) activation and alleviates the inflammatory response in microglia. However, the mechanism is still largely unknown. In this study, western blot analysis and enzyme-linked immunosorbent assay were utilized for evaluating the extent of NF-κB activation and expression of proinflammatory cytokines. qPCR and western blot analysis were performed to detect SENP1 expression. Coimmunoprecipitation followed by western blot analysis was applied to measure the changes in SUMOylation of NF-κB essential modulator (NEMO) and P65 in microglia with or without overexpression of SENP1. As the results, we found that intermittent hypoxia (IH) triggered the activation of NF-κB and upregulated the expression levels of tumor necrosis factor-α and interleukin-6. Interestingly, our data indicated that the SUMOylation of NEMO was enhanced by IH while SUMOylation of P65 was not affected. Further, our data showed that overexpression of SENP1 could decrease the extent of NF-κB activation and inhibit the inflammatory response of microglia through regulating the SUMOylation of NEMO. Collectively, this study presents the first report of the SENP1-controlled de-SUMOylation process of NEMO and its critical role in regulating NF-κB activation and proinflammatory cytokines secretion in microglia cells. This study would benefit for clarifying the role of SENP1 in IH-induced activation of microglia, thus providing potential therapeutic targets for obstructive sleep apnea treatment.

Sleep mediates the association between homocysteine and oxidative status in mild cognitive impairment

Tremendous progress has been made over the last few years in understanding how sleep and amyloid-β (Aβ) cooperate to speed up the progression of Alzheimer's disease (AD). However, it remains unknown whether sleep deficits also interact with other risk factors that exacerbate the pathological cascade of AD. Based on evidence showing that higher levels of homocysteine (HCY) and sleep loss increase oxidative damage, we here investigate whether the relationship between HCY and total antioxidant capacity (TAC) is mediated by changes in objective sleep in healthy older (HO, N = 21) and mild cognitive impairment (MCI, N = 21) subjects. Results revealed that reduced TAC levels in MCI was significantly correlated with increased HCY, shorter sleep duration, lower sleep efficiency, and reduced volume of temporal regions. However, only the HCY-TAC association showed diagnostic value, and this relationship was mediated by poorer sleep quality in MCI patients. We further showed that HCY-related cerebral volume loss in MCI depended on the serial relationship between poorer sleep quality and lower TAC levels. These findings provide novel insights into how impaired sleep may contribute to maintain the relationship between HCY and oxidative stress in prodromal AD, and offer empirical foundations to design therapeutic interventions aimed to weaken this link.

Nocturnal heart rate variation in diabetic and non-diabetic patients with sleep apnea syndrome

OBJECTIVES

Heart rate variability (HRV) analysis is used for the evaluation of autonomic function in the cardiovascular system. Decreased HRV is associated with disorders affecting the autonomous system such as diabetes mellitus (DM) and obstructive sleep apnea (OSA). Previous studies have shown an association between OSA and DM. However, the interrelationships of HRV with OSA and DM are not well known. The aim of this study was to assess nocturnal HRV in patients who suffered from OSA with and without DM.

METHODS

Sixty patients with OSA (27 with DM and 33 non-DM) underwent polysomnography for eight hours starting at midnight. From electrocardiogram (ECG) recordings taken as a part of polysomnography, time-domain and frequency-domain HRV parameters were evaluated to compare patients with regard to nocturnal HRV components such as low frequency (LF) and high frequency (HF), apnea-hypopnea index (AHI) and sleep parameters.

RESULTS

In the non-DM group, a direct relationship was observed between AHI and HRV rather than very low frequency (VLF) and LF/HF variables. This relationship was just significant between AHI and standard deviation of five-min average of normal R-R intervals and adjacent R-R intervals differing by 0.50 ms over 24 h (p < 0.05). In the DM group, the correlation between AHI and HRV parameters except HF and waking frequency was direct and non-significant. Intergroup comparison showed a significant difference between groups regarding AHI and HRV-index, LF and VLF (p < 0.05).

CONCLUSIONS

DM can affect HRV; however, this is not the case in OSA patients. This means that in the presence of OSA, the DM effect on HRV disappears.

Association of Autonomic Dysfunction and Mild Obstructive Sleep Apnea

BACKGROUND: Autonomic dysfunction (AD) has been independently associated with obstructive sleep apnea (OSA). Autonomic abnormalities are generally considered to be secondary to OSA. Autonomic dysfunction may also contribute to OSA. If AD contributes to OSA, we postulated that abnormalities may be present in mild OSA where the confounding causal effects of hypoxemia and sleep disruption are reduced.

OBJECTIVE: We evaluated autonomic function tests and sleep studies in a cohort of subjects with no known diagnosis of OSA.

METHODS: We prospectively enrolled a cohort without diagnosed OSA who were part of an ongoing study of vasomotor rhinitis (VMR) for testing. A battery of autonomic nervous system tests (sudomotor and cardiovagal), nonattended polysomnography, and three-site esophageal/pharyngeal pH monitoring were performed.

RESULTS: Twenty of 22 patients completed the test battery and 12 (60%) met criteria for OSA (Apnea/Hypopnea Index “AHI” >5 events/hour). AHI correlated to mean tilt table blood pressure decrease (R = 0.58, P = 0.007) and the Valsalva-mediated phase 2 mean blood pressure decrease (R = 0.52, P = 0.017). OSA severity was related to sympathetic but not parasympathetic abnormalities. No differences in blood pressure responses were related to age, oxygen desaturation nadir, gastroesophageal reflux, VMR, or sleepiness.

CONCLUSION: Autonomic abnormalities suggestive of decreased adrenergic tone are associated with mild OSA. These abnormalities may potentially be secondary but may also precede development of OSA. (Otolaryngol Head Neck Surg 2004;130: 643-8.)

Excessive daytime sleepiness and fatigue may indicate accelerated brain aging in cognitively normal late middle-aged and older adults

Excessive daytime sleepiness (EDS) and fatigue increases with age. The aim of this study was to investigate the association between EDS and fatigue with cortical thickness and hippocampal volume in cognitively normal, late middle-aged and older adults. We performed a cross-sectional observational study of 1374 cognitively-normal subjects aged 50 years and older who had a structural MRI. Regional cortical thickness and hippocampal volume were measured. Multiple linear regression models were fit to explore associations between EDS and fatigue and structural MRI measures in different brain regions, adjusting for multiple covariates. EDS was defined as Epworth Sleepiness Scale ≥10. Fatigue severity was assessed with the Beck Depression Inventory-2. 208 participants had EDS, 27 had significant fatigue, and 11 had both. Participants with EDS or fatigue had significantly lower cognitive scores, more disturbed sleep, and medical comorbidities. The presence of EDS was associated with both global and regional atrophy, whereas fatigue was more associated with frontal and temporal changes. Cortical thinning predicted by EDS and fatigue was maximal in the temporal region with average reduction of 34.2 μm (95% CI, -54.1, -14.3; P = 0.001) and 90.2 μm (95% CI, -142.1, -38.2; P = 0.001), respectively. Fatigue was also associated with hippocampal volume reduction of -374.2 mm³ (95% CI, -670.8, -77.7; P = 0.013). Temporal cortical thinning predicted by presence of EDS and fatigue was equivalent to more than 3.5 and 9 additional years of aging, respectively. EDS and fatigue were associated with cortical thickness reduction primarily in regions with increased age-susceptibility, which may indicate accelerated brain aging.

A new algorithm for the detection of sleep apnea events in respiration signals

Sleep apneas are the most common type of sleep-related breathing disorders which cause a patient to move from a good sleep into an inefficient sleep. In addition, sleep apnea widely impacts the American population and is a large cost for healthcare. Traditional detection methods of sleep apneas are complex, expensive, and invasive to most patients. Among the various physiological signals, respiration signals are relatively easy to be monitored. However, not many studies are conducted using respiration signal only, and most of the previous algorithms are insufficient to detect apnea events. In this paper, we propose a new algorithm based on only the respiration signal to detect the apnea events during sleep and conduct experiments comparing the performance of our algorithm against two apnea detection algorithms. We use 20 patients' data, all of whom have severe Apnea Hypopnea Index (AHI>30: over 30 events per hour). Our study shows that our algorithm outperforms the other two algorithms.

Predictability decomposition detects the impairment of brain-heart dynamical networks during sleep disorders and their recovery with treatment

This work introduces a framework to study the network formed by the autonomic component of heart rate variability (cardiac processη) and the amplitude of the different electroencephalographic waves (brain processes δ, θ, α, σ, β) during sleep. The framework exploits multivariate linear models to decompose the predictability of any given target process into measures of self-, causal and interaction predictability reflecting respectively the information retained in the process and related to its physiological complexity, the information transferred from the other source processes, and the information modified during the transfer according to redundant or synergistic interaction between the sources. The framework is here applied to theη,δ,θ,α,σ,βtime series measured from the sleep recordings of eight severe sleep apnoea-hypopnoea syndrome (SAHS) patients studied before and after long-term treatment with continuous positive airway pressure (CPAP) therapy, and 14 healthy controls. Results show that the full and self-predictability of η, δ and θ decreased significantly in SAHS compared with controls, and were restored with CPAP forδandθbut not forη The causal predictability of η and δ occurred through significantly redundant source interaction during healthy sleep, which was lost in SAHS and recovered after CPAP. These results indicate that predictability analysis is a viable tool to assess the modifications of complexity and causality of the cerebral and cardiac processes induced by sleep disorders, and to monitor the restoration of the neuroautonomic control of these processes during long-term treatment.

Obstructive sleep apnea presenting as pseudopheochromocytoma

A 52-year-old female with a history of poorly controlled resistant hypertension was admitted to our hospital with severe hypertension. She had a history of fatigue and intermittent episodes of palpitations. Laboratory evaluation was significant for elevated 24-h urinary catecholamine levels (3,5 times the upper normal levels). This case was presenting with a clinical and biochemical picture indistinguishable from that of pheochromocytoma. However, neither computed tomography nor meta-iodo-benzyl-guanidine scintigraphy detected any catecholamine-producing tumor in or outside the adrenal glands. Our patient was screened with full polysomnography because of heavy snoring, daytime somnolence and obesity. It revealed severe obstructive sleep apnea syndrome. After three months of continuous positive airway pressure therapy, the patient experienced resolution of his presenting symptoms, improved blood pressure control and normalization of his urinary catecholamine levels. This case highlights sleep disordered breathing as a potentially reversible cause of pseudo-pheochromocytoma.

Increased Risk of Stroke in Patients With Fibromyalgia: A Population-BASED Cohort Study

Neuropsychiatric diseases might enhance stroke development, possibly through inflammation and atherosclerosis. Approximately 25% to 40% of patients with stroke, largely younger patients, are not associated with any conventional stroke risk factors. In this research, we explored whether fibromyalgia (FM), a neuropsychosomatic disorder, increases stroke risk.From a claims dataset with one million enrollees sourced of the Taiwan National Health Insurance database, we selected 47,279 patients with FM and randomly selected 189,112 age- and sex-matched controls within a 3-year period from January 1, 2000 to December 31, 2002. Stroke risk was assessed using Cox proportional hazards regression.Comorbidities associated with increased stroke risk, such as hypertension, diabetes, hyperlipidemia, coronary heart disease, irritable bowel syndrome, and interstitial cystitis, were more prevalent in patients with FM and high stroke risk than in the controls. The overall stroke risk was 1.25-fold (95% confidence interval [CI]: 1.21-1.30) higher in the FM group than in the non-FM group. Even without comorbidities, stroke risk was higher in patients with FM than in the controls (adjusted hazard ratio [aHR] = 1.44, 95% CI: 1.35-1.53, P < 0.001). The relative risk of stroke was 2.26-fold between FM and non-FM groups in younger patients (age <35 years, 95% CI: 1.86-2.75).This is the first investigation associating FM with an increased risk of stroke development. The outcomes imply that FM is a significant risk factor for stroke and that patients with FM, particularly younger patients, require close attention and rigorous measures for preventing stroke.

Effect of adenotonsillectomy on ADHD symptoms of children with adenotonsillar hypertrophy and sleep disordered breathing

BACKGROUND

Adenotonsillar hypertrophy is the most common etiologic agent for the obstruction of the upper airways in children, which might be associated with attention-deficit hyperactivity disorder (ADHD), one of the most common psychiatric disorders of childhood. Despite the concurrence of these two conditions, i.e., obstruction of the airways and ADHD, no exact etiologic relationship has been established between adenotonsillectomy (AT) and ADHD symptoms. This study was undertaken to evaluate the effect of AT on the ADHD symptoms in children with adenotonsillar hypertrophy and sleep disordered breathing (SDB).

METHODS

The design of the present study consisted of pre-test and post-test, followed by post hoc tests. Fifty-three children aged 3-12 were included in this study, selected from those referring to the Pediatric Hospital of Tabriz University of Medical Sciences, with SDB, adenotonsillar hypertrophy and ADHD based on DSM-IV criteria, by availability of the subjects undergoing adenotonsillectomy after evaluation of the severity of ADHD symptoms. The scores of ADHD symptoms were evaluated before AT and at 3- and 6-month postoperative intervals based on Conner's Parent Rating Scale-Revised (CPRS-R) Questionnaire. Repeated-measures ANOVA and Fisher's exact test were used for data analysis.

RESULTS

AT resulted in a significant decrease in the severity of ADHD symptoms (oppositional behavior, cognitive disorders, inattention, hyperactivity and ADHD index) at 3- and 6-month postoperative intervals (P<0.001), with more significant decreases at 6-month postoperative interval compared to 3-month interval (P<0.001).

CONCLUSIONS

Based on the results of this pilot study, AT in children with SDB associated with ADHD resulted in a significant decrease in the severity of ADHD symptoms.

Hematological Parameters as Predictors of Cardiovascular Disease in Obstructive Sleep Apnea Syndrome Patients

We investigated the role of the red cell distribution width (RDW) and other parameters including platelet (PLT) count, mean platelet volume (MPV), and platelet distribution width (PDW) in patients with obstructive sleep apnea syndrome (OSAS) having cardiovascular diseases (CVDs). Patients (n = 142) having sleep disorders and who applied for a night polysomnography were included in this study. For statistical analysis, chi-square test, bivarite correlation, and logistic and stepwise regression tests were used. A positive correlation between RDW MPV, RDW, and body mass index as well as PLT and apnea-hypopnea index were observed. A negative correlation between AHI and PDW (P= .041) and a positive correlation between AHI and PLT (P= .010) were found in the patients ≥40 years old with CVD. The RDW was higher in patients ≥40 years old who had CVD (P= .016), and 19% of them had RDW >14%. The PDW (odds ratio = 6.02 [95% confidence interval = 1.3-28.2],P= .023) appeared to be associated with increased risk of hyperlipidemia in patients with severe OSAS. If these results are confirmed, RDW could be used with other markers, especially PLT and PDW, in prediction of CVD in patients with severe OSAS.

Vascular factors and multiple measures of early brain health: CARDIA brain MRI study

OBJECTIVE

To identify early changes in brain structure and function that are associated with cardiovascular risk factors (CVRF).

DESIGN

Cross-sectional brain Magnetic Resonance I (MRI) study.

SETTING

Community based cohort in three U.S. sites.

PARTICIPANTS

A Caucasian and African-American sub-sample (n= 680; mean age 50.3 yrs) attending the 25 year follow-up exam of the Coronary Artery Risk Development in Young Adults Study.

PRIMARY AND SECONDARY OUTCOMES

3T brain MR images processed for quantitative estimates of: total brain (TBV) and abnormal white matter (AWM) volume; white matter fractional anisotropy (WM-FA); and gray matter cerebral blood flow (GM-CBF). Total intracranial volume is TBV plus cerebral spinal fluid (TICV). A Global Cognitive Function (GCF) score was derived from tests of speed, memory and executive function.

RESULTS

Adjusting for TICV and demographic factors, current smoking was significantly associated with lower GM-CBF and TBV, and more AWM (all <0.05); SA with lower GM-CBF, WM-FA and TBV (p=0.01); increasing BMI with decreasing GM-CBF (p<0003); hypertension with lower GM-CBF, WM-FA, and TBV and higher AWM (all <0.05); and diabetes with lower TBV (p=0.007). The GCS was lower as TBV decreased, AWM increased, and WM-FA (all p<0.01).

CONCLUSION

In middle age adults, CVRF are associated with brain health, reflected in MRI measures of structure and perfusion, and cognitive functioning. These findings suggest markers of mid-life cardiovascular and brain health should be considered as indication for early intervention and future risk of late-life cerebrovascular disease and dementia.

Factors associated with reported snoring among elderly patients attending the geriatric centre in Nigeria

INTRODUCTION

Snoring is the major symptom of sleep disordered breathing (SDB) which is of immense public health importance. It is associated with some morbidities and mortality in the elderly. Few studies have addressed this problem in the elderly Nigerians.

METHODS

Cross-sectional study of 843 elderly patients at the Geriatric Centre, University College Hospital, Ibadan, Nigeria. Data were collected on the following candidate variables which may be associated with snoring such as socio-demographic characteristics, morbidities, lifestyle habits and functional disability using Katz index. Anthropometric measurements such as body mass index and neck, waist and hip circumferences were taken. Statistical analysis was done with SPSS 17.

RESULTS

The point prevalence of reported snoring was 31.2%. Habitual snoring was reported by 24.8%. Snoring was significantly associated with obesity, moderate to severe oropharyngeal crowding, wide neck and waist circumferences in both sexes. Logistic regression analysis showed wide neck circumference (OR = 6.005; 95%CI= 2.150-16.770) among the males and obesity (OR = 2.028; 95%CI= 1.344-3.061) and moderate to severe oropharyngeal crowding (OR = 1.639; 95%CI= 1.057-2.543) in the females to be the most significant factors associated with snoring.

CONCLUSION

The high prevalence of snoring among elderly patients in Nigeria calls for concerted effort by healthcare workers to educate the elderly.

Nocturnal snoring decreases daytime baroreceptor sensitivity

BACKGROUND

In patients with obstructive sleep apnea heart rate variability and baroreceptor sensitivity during night and daytime are impaired. Snoring without obstructive sleep apnea may already influence heart rate variability and baroreceptor sensitivity during daytime.

METHODS

Cardiovascular daytime testing was performed in 11 snorers and age, BMI, and gender matched controls. Sleep apnea and snoring were quantified by sleep recordings. Paced breathing was performed during daytime with ECG, non-invasive blood pressure, and respiration recorded. Heart rate variability and blood pressure variability were analyzed in the time and frequency domain. Baroreceptor sensitivity (alpha gain) was calculated.

RESULTS

In snorers a significant increase in high frequency systolic blood pressure variability (SBPV-HF) compared to control group (0.37 mm Hg(2) vs. 0.11 mm Hg(2) for 12 breaths and 0.35 mm Hg(2) vs. 0.10 mm Hg(2) for 15 breaths) was demonstrated. Furthermore a lower baroreceptor sensitivity was found in snorers compared to controls (9.2 ms/mm Hg vs. 16.2 ms/mm Hg for 12 breaths and 8.5 ms/mm Hg vs. 17.4 ms/mm Hg for 15 breaths per minute) using the paced breathing protocol. Mean heart rate was elevated in snorers as well.

CONCLUSIONS

Snorers may have a reduced parasympathetic tone during daytime rather than an increased sympathetic tone.

Qualidade do sono e tolerância ao esforço em portadores de apneia obstrutiva do sono

INTRODUÇÃO: O sono é um estado natural e recorrente, no qual acontecem processos neurobiológicos importantes. A má qualidade do sono está diretamente associada com piores indicadores de saúde. A qualidade do sono pode ser medida objetiva e subjetivamente por métodos como a polissonografia, que é o padrão de referência, ou por meio de testes e questionários, como o índice de qualidade de sono de Pittsburgh (IQSP).OBJETIVO: Correlacionar a qualidade do sono com a tolerância ao esforço em pacientes portadores da síndrome da apneia/hipopneia obstrutiva do sono (SAHOS).MÉTODOS: Participaram do estudo 63 indivíduos (57 mulheres e seis homens), média de idade de 51,7 ± 6,6 anos; índice de massa corpórea (IMC) média de 28,2 ± 5,0 kg/m2); índice de apneia/hipopneia (IAH) médio de 7,3 ± 10,50 eventos/hora, verificado através da polissonografia. Para a avaliação da qualidade do sono, os participantes responderam ao IQSP, e para a avaliação da tolerância ao esforço, realizaram o teste de caminhada de 6 minutos (TC6M).RESULTADOS: Não houve correlação entre o IQSP e o TC6M (Rs= -0,103620, p = 0,419), assim como entre o IAH e o TC6M (Rs= -0, 000984, p = 0,9939). Podemos sugerir que a qualidade do sono e a gravidade da SAHOS não afetam a tolerância ao esforço dos indivíduos com SAHOS.CONCLUSÃO: Estudos com uma amostra maior, levando-se em consideração a estratificação pela gravidade da SAHOS e utilizando métodos mais acurados de avaliação da capacidade funcional, devem ser realizados, a fim de que resultados mais abrangentes possam ser obtidos.

Function and modulation of premotor brainstem parasympathetic cardiac neurons that control heart rate by hypoxia-, sleep-, and sleep-related diseases including obstructive sleep apnea

Parasympathetic cardiac vagal neurons (CVNs) in the brainstem dominate the control of heart rate. Previous work has determined that these neurons are inherently silent, and their activity is largely determined by synaptic inputs to CVNs that include four major types of synapses that release glutamate, GABA, glycine, or serotonin. Whereas prior reviews have focused on glutamatergic, GABAergic and glycinergic pathways, and the receptors in CVNs activated by these neurotransmitters, this review focuses on the alterations in CVN activity with hypoxia-, sleep-, and sleep-related cardiovascular diseases including obstructive sleep apnea.

A multi-feature classification approach to detect sleep apnea in an ultrasonic upper airway occlusion detector system

Obstructive Sleep Apnea (OSA) is the most common form of sleep disorder breathing. It is estimated that this insidious disease affects 15% of the US adult population. Current procedure of diagnosing OSA requires polysomnography (NPSG) conducted in accredited sleep laboratories and the data getting scored by certified sleep technicians, a costly process that is not readily available in all areas. Ultrasonic techniques are increasingly used in the area of medical diagnosis and treatments due to their safety and economic costs. This paper investigates a feasibility study of a multi-channel ultrasonic OSA detection system. The approach utilizes wavelet-based as well as temporal and spectral features extracted from multiple ultrasound waves transmitted through patient's neck during sleep. Using NPSG data as gold standard, the proposed classifier makes a preliminary decision on the data sequence by labeling epochs as normal or apneic. A Finite State Machine (FSM) is employed to update the classified labels for a more robust detection. Experimental results on three sleep disordered patients suggest that it may be feasible to consider the proposed approach for an ultrasound based detection system.

The incidence and severity of pulmonary hypertension in obstructive sleep apnea with hypothyroidism

BACKGROUND

Hypothyroidism and obstructive sleep apnea (OSA) are both common health problems and can be seen together. Each of these 2 diseases can cause pulmonary hypertension (PH). We aimed to determine whether hypothyroidism with OSA has a significant effect on the frequency and severity of PH.

MATERIAL AND METHODS

A total of 236 patients were included in the study. Patients were divided into 3 groups: Group I, Obstructive Sleep Apnea (n=149); Group II, Hypothyroidism (n=56); and Group III, Obstructive Sleep Apnea-Hypothyroidism (n=31). All patients underwent polysomnography and echocardiography and serum levels of thyroid-stimulating hormone (TSH) and free thyroxine 4 (FT4) were analyzed.

RESULTS

There were 167 male and 69 female participants, and the mean age was 47.8 ± 11.5 (Group I: 81.9% male, 18.1% female; Group II: 44.6% male, 55.4% female; Group III: 64.6% male, 35.4% female). Distribution of mean pulmonary arterial pressure on echocardiography was statistically different among the 3 groups (x(2)=14.99, p=0.006). When adjusted according to the apnea-hypopnea index (AHI), age, and body mass index (BMI), a significant relation with PH was determined (p=0.002).

CONCLUSIONS

The combination of hypothyroidism with OSA is associated with an increased frequency and severity of PH. When PH is found out of line with the severity of OSA, thyroid dysfunction should be investigated.

Targeted ablation at stable atrial fibrillation sources improves success over conventional ablation in high-risk patients: a substudy of the CONFIRM Trial

BACKGROUND

Pulmonary vein (PV) isolation has disappointing results in patients with obesity, heart failure, obstructive sleep apnea (OSA) and enlarged left atria (LA), for unclear reasons. We hypothesized that these comorbidities may cause higher numbers or non-PV locations of atrial fibrillation (AF) sources, where targeted source ablation (focal impulse and rotor modulation [FIRM]) should improve the single-procedure success of ablation.

METHODS

The Conventional Ablation of AF With or Without Focal Impulse and Rotor Modulation (CONFIRM) trial prospectively enrolled 92 patients at 107 AF ablation procedures, in whom computational mapping identified AF rotors or focal sources. Patients underwent FIRM plus conventional ablation (FIRM-guided), or conventional ablation only, and were evaluated for recurrent AF quarterly with rigourous, often implanted, monitoring. We report the n = 73 patients undergoing first ablation in whom demographic information was available (n = 52 conventional, n = 21 FIRM-guided).

RESULTS

Stable sources for AF were found in 97.1% of patients. The numbers of concurrent sources per patient (2.1 ± 1.1) rose with LA diameter (P = 0.021), lower left ventricular ejection fraction (P = 0.039), and the presence of OSA (P = 0.002) or hypomagnesemia (P = 0.017). Right atrial sources were associated with obesity (body mass index ≥ 30; P = 0.015). In patients with obesity, hypertension, OSA, and LA diameter > 40 mm, single-procedure freedom from AF was > 80% when FIRM-guided was used vs. < 50% when conventional ablation was used (all; P < 0.05).

CONCLUSIONS

Patients with "difficult to treat" AF exhibit more concurrent AF sources in more widespread biatrial distributions than other patients. These mechanisms explain the disappointing results of PV isolation, and how FIRM can identify patient-specific AF sources to enable successful ablation in this population.

Long-term CPAP treatment partially improves the link between cardiac vagal influence and delta sleep

BACKGROUND

Continuous positive airway pressure (CPAP) treatment improves the risk of cardiovascular events in patients suffering from severe sleep apnea-hypopnea syndrome (SAHS) but its effect on the link between delta power band that is related to deep sleep and the relative cardiac vagal component of heart rate variability, HF(nu) of HRV, is unknown. Therefore, we tested the hypothesis that CPAP restores the link between cardiac autonomic activity and delta sleep across the night.

METHODS

Eight patients suffering from severe SAHS before and after 4 ± 3 years of nasal CPAP treatment were matched with fourteen healthy controls. Sleep EEG and ECG were analysed to obtain spectral sleep and HRV components. Coherence analysis was applied between HF(nu) and delta power bands across the first three sleep cycles.

RESULTS

Sleep characteristics and spectral HRV components were similar between untreated patients, treated patients and controls, with the exception of decreased Rapid Eye Movement duration in untreated patients. Coherence and gain values between HF(nu) and delta EEG variability were decreased in untreated patients while gain values normalized in treated patients. In patients before and during long-term CPAP treatment, phase shift and delay between modifications in HF(nu) and delta EEG variability did not differ from controls but were not different from zero. In healthy men, changes in cardiac vagal activity appeared 9 ± 7 minutes before modifications in delta sleep.

CONCLUSIONS

Long-term nasal CPAP restored, in severe SAHS, the information between cardiovascular and sleep brainstem structures by increasing gain, but did not improve its tightness or time shift.

Association between self reported snoring, STOP questionnaire and postoperative pulmonary complications in patients submitted to ortophaedic surgery

Background

Obstructive sleep apnea (OSA) may increase perioperative complications. The aim of this study was to determine the relationship among postoperative pulmonary complication, snoring and STOP questionnaire in patients with ortophaedic surgery.

Methods

1,406 consecutive records of patients who had undergone elective ortophaedic surgery during the period January 2005-December 2008 were investigated retrospectively. Demographic information, sleep symptoms, STOP questionnaire, comorbidities and outcome data were collected.

Results

There were 289 (20.5%) snorers and 1,117 (79.5%) non-snorers in the study group. There was no significant difference between snorer and non-snorer patients (p > 0.05) in the prevalence of pneumonia and respiratory failure. But in snorer patients the rate of postoperative atelectasis was significantly higher than in non-snorer group (p < 0.0001). The STOP Questionnaire was given to 1,406 patients and 147 (10.4%) out of them were classified at high risk of OSA. There was no significant difference in the prevalence of pneumonia and respiratory failure between low and high risk group (p > 0.05). However, in high risk patients the occurrence of postoperative atelectasis was significantly higher than in low risk group (p < 0.0001).

Conclusion

Postoperative atelectasis was significantly more prevalent in the high risk group according to STOP questionnaire.

Sleep apnea and atrial fibrillation; 2012 update

Atrial fibrillation (AF) and obstructive sleep apnea (OSA) are very prevalent diseases in modern society. Recent years have seen the emergence of a wide body of literature suggesting an important association between these two diseases. This review will provide a summary of this evidence as it currently exists. First, it will review the literature suggesting an association between AF and OSA by highlighting the prevalence of AF in OSA, the correlation of AF prevalence with OSA severity and the trend towards increased AF recurrence in patients with OSA after treatment for AF. Second, it will identify the possible pathophysiologic mechanisms for this association. In doing so, it will discuss the investigated effects of intrathoracic pressure changes, autonomic instability and atrial remodeling. Finally, it will review the evidence of the effect of treatment of OSA on AF, highlighting the role of continuous positive airway pressure (CPAP) in the treatment of OSA and its impact on AF prevalence and recurrence.

Etiopathogenetic mechanisms of pulmonary hypertension in sleep-related breathing disorders

Obstructive sleep apnea syndrome is a common disorder with significant health consequences and is on the rise in consonance with the obesity pandemic. In view of the association between sleep-disordered breathing and pulmonary hypertension as depicted by multiple studies, current clinical practice guidelines categorize obstructive sleep apnea as a risk factor for pulmonary hypertension and recommend an assessment for sleep disordered breathing in evaluating patients with pulmonary hypertension. The dysregulatory mechanisms associated with hypoxemic episodes observed in sleep related breathing disorders contribute to the onset of pulmonary hypertension and identification of these potentially treatable factors might help in the reduction of overall cardiovascular mortality.

[Sleep-disordered breathing and cardiac resynchronization therapy]

Patients with progressive heart failure often suffer from sleep-disordered breathing (SDB). Upon receiving cardiac resynchronization therapy (CRT), there is an improvement of cardiac function and central sleep apnea syndrome (CSA) with Cheyne-Stokes respiration; however, effects of CRT on obstructive sleep apnea syndrome seemed to be without clinical relevance. Likewise, additional atrial overdrive pacing did not improve CRT effects relevantly in CSA patients. During CRT, there is an improvement in sleep parameters, sleep quality by reduction of depressive syndromes, and in long-term survival. Therefore, all patients with chronic heart failure and indication for CRT should be monitored regarding SDB before and after CRT device implantation.

Upper airway occlusion detection using a novel ultrasound technique

Obstructive sleep apnea/hypopnea Syndrome (OSAHS) is the most common form of Sleep Disordered Breathing (SDB) and it is estimated to affect approximately 15% of US adult population. In this paper, we report on the results of in vivo experiments of an ultrasonic device for the non-invasive detection of obstructive sleep apnea/hypopnea (OSAH). A description of the ultrasonic system used is presented, followed by the results of a full night sleep study. The findings show a significant difference in the spectral features extracted from the received ultrasonic waveform during apneic breathing, compared to the hyperventilation that follows. Therefore, the findings indicate the feasibility of developing an ultrasonic detection device for low cost diagnosis of SDB.

Peripheral vasoconstriction and abnormal parasympathetic response to sighs and transient hypoxia in sickle cell disease

RATIONALE

Sickle cell disease is an inherited blood disorder characterized by vasoocclusive crises. Although hypoxia and pulmonary disease are known risk factors for these crises, the mechanisms that initiate vasoocclusive events are not well known.

OBJECTIVES

To study the relationship between transient hypoxia, respiration, and microvascular blood flow in patients with sickle cell.

METHODS

We established a protocol that mimics nighttime hypoxic episodes and measured microvascular blood flow to determine if transient hypoxia causes a decrease in microvascular blood flow. Significant desaturations were induced safely by five breaths of 100% nitrogen.

MEASUREMENTS AND MAIN RESULTS

Desaturation did not induce change in microvascular perfusion; however, it induced substantial transient parasympathetic activity withdrawal in patients with sickle cell disease, but not controls subjects. Marked periodic drops in peripheral microvascular perfusion, unrelated to hypoxia, were triggered by sighs in 11 of 11 patients with sickle cell and 8 of 11 control subjects. Although the sigh frequency was the same in both groups, the probability of a sigh inducing a perfusion drop was 78% in patients with sickle cell and 17% in control subjects (P < 0.001). Evidence for sigh-induced sympathetic nervous system dominance was seen in patients with sickle cell (P < 0.05), but was not significant in control subjects.

CONCLUSIONS

These data demonstrate significant disruption of autonomic nervous system balance, with marked parasympathetic withdrawal in response to transient hypoxia. They draw attention to an enhanced autonomic nervous system–mediated sigh–vasoconstrictor response in patients with sickle cell that could increase red cell retention in the microvasculature, promoting vasoocclusion.