Associations of Moderate to Severe Asthma with Obstructive Sleep Apnea

Purpose

This study aimed to evaluate the correlation between associating factors of moderate to severe asthma with obstructive sleep apnea (OSA).

Materials and Methods

One hundred and sixty-seven patients who visited the pulmonary and sleep clinic in Severance Hospital presenting with symptoms of sleep-disordered breathing were evaluated. All subjects were screened with ApneaLink. Thirty-two subjects with a high likelihood of having OSA were assessed with full polysomnography (PSG).

Results

The mean age was 58.8±12.0 years and 58.7% of subjects were male. The mean ApneaLink apnea-hypopnea index (AHI) was 12.7±13.0/hr. The mean ApneaLink AHI for the 32 selected high risk patients of OSA was 22.3±13.2/hr, which was lower than the sleep laboratory-based PSG AHI of 39.1±20.5/hr. When OSA was defined at an ApneaLink AHI ≥5/hr, the positive correlating factors for OSA were age, male gender, and moderate to severe asthma.

Conclusion

Moderate to severe asthma showed strong correlation with OSA when defined at an ApneaLink AHI ≥5/hr.     

Social inequalities in sleep‐disordered breathing: Evidence from the CoLaus|HypnoLaus study

Sleep‐disordered breathing is a common condition, related to a higher cardiometabolic and neurocognitive risk. The main risk factors for sleep‐disordered breathing include obesity, craniofacial characteristics, male sex and age. However, some studies have suggested that adverse socioeconomic circumstances and lifestyle‐related behaviours such as smoking and alcohol use, may also be risk factors for sleep‐disordered breathing. Here, we investigate the associations between socioeconomic status and sleep‐disordered breathing, as measured by sleep apnea–hypopnea and oxygen desaturation indexes. Furthermore, we assess whether these associations are explained by lifestyle‐related factors (smoking, sedentary behaviour, alcohol use and body mass index [BMI]). We used data from the CoLaus|HypnoLaus study, a population‐based study including 2162 participants from Lausanne (Switzerland). Socioeconomic status was measured through occupation and education. Sleep‐disordered breathing was assessed through polysomnography and measured using the apnea–hypopnea index (AHI: number of apnea/hypopnea events/hr: ≥15/≥30 events), and the ≥3% oxygen desaturation index (ODI: number of oxygen desaturation events/hr: ≥15/≥30 events). Lower occupation and education were associated with higher AHI and ODI (occupation: AHI30, odds ratio (OR) = 1.88, 95% confidence interval (CI) [1.07; 3.31]; ODI30, OR = 2.29, 95% CI [1.19; 4.39]; education: AHI30, OR = 1.21, 95% CI [0.85; 1.72]; ODI30, OR = 1.26, 95% CI [0.83; 1.91]). BMI was associated with socioeconomic status and AHI/ODI, and contributed to the socioeconomic gradient in SDB, with mediation estimates ranging between 43% and 78%. In this Swiss population‐based study, we found that low socioeconomic status is a risk factor for sleep‐disordered breathing, and that these associations are partly explained by BMI. These findings provide a better understanding of the mechanisms underlying social differences in sleep‐disordered breathing and may help implement policies for identifying high‐risk profiles for this disorder.     

Prediction of sleep-disordered breathing by unattended overnight oximetry

Between January 1994 and July 1997, 793 patients suspected of having sleep-disordered breathing had unattended overnight oximetry in their homes followed by laboratory polysomnography. From the oximetry data we extracted cumulative percentage time at SaO2 < 90% (CT90) and a saturation variability index (delta Index, the sum of the differences between successive readings divided by the number of readings - 1). CT90 was weakly correlated with polysomnographic apnea/hypopnea index (AHI). (Spearman rho = 0.36, P < 0.0001) and with delta Index (rho = 0.71, P < 0.0001). delta Index was more closely correlated with AHI (rho = 0.59, P < 0.0001). In a multivariate model, only delta Index was significantly related to AHI, the relationship being AHI = 18.8 delta Index + 7.7. The 95% CI for the coefficient were 16.2, 21.4, and for the constant were 5.8, 9.7. The sensitivity of a delta Index cut-off of 0.4 for the detection of AHI > or = 15 was 88%, for detection of AHI > or = 20 was 90% and for the detection of AHI > or = 25 was 91%. The specificity of delta Index > or = 0.4 for AHI > or = 15 was 40%. In 113 further patients, oximetry was performed simultaneously with laboratory polysomnography. Under these circumstances delta Index was more closely correlated with AHI (rho = 0.74, P < 0.0001), as was CT90 (rho = 0.58, P < 0.0001). Sensitivity of delta Index > or = 0.4 for detection of AHI > or = 15 was not improved at 88%, but specificity was better at 70%. We concluded that oximetry using a saturation variability index is sensitive but nonspecific for the detection of obstructive sleep apnea, and that few false negative but a significant proportion of false positive results arise from night-to-night variability.     

Respiratory and body movements as indicators of sleep stage and wakefulness in infants and young children

Conventional polysomnographic (PSG) sleep staging to sleep staging based on a static-charge-sensitive bed (SCSB) recording in infants and young children was compared. The study consisted of whole-night clinical sleep studies in 22 children at 24 weeks (SD 24, range 1–79 weeks) of age. Most of the children presented with respiratory disturbances during sleep. From the SCSB record, sleep stages were differentiated according to regularity of breathing, presence of body movements, and most important, presence of high-frequency components of breathing (SCSB spikes). With both methods, three sleep/wake stages were distinguished: rapid eye movement (REM) sleep, non-rapid eye movement (NREM) sleep and wakefulness. The average inter-scorer reliability of the PSG sleep staging controlled in nine subjects was 88%. The average concordance between the two methods ranged from 82 to 85%, depending on the criteria used for scoring the SCSB. The mean sensitivity of the SCSB to detect NREM sleep ranged from 77 to 90% and the mean sensitivity to detect REM sleep ranged from 61 to 86%. The mean positive predictive value was 89–96% for NREM sleep and 54–67% for REM sleep. In conclusion, REM sleep is characterized by irregular breathing with superimposed fast respiratory movements. These changes are specific enough to allow distinction between episodes of NREM sleep, REM sleep and wakefulness with the non-invasive SCSB method in infants and young children. Incomplete concordance between PSG and SCSB score was most frequently observed during sleep stage transition periods, where the behavioural state and electrophysiological criteria disagreed. When combined with the PSG, the SCSB provides complementary information about the behavioural state of child.     

The severity of individual obstruction events is related to increased mortality rate in severe obstructive sleep apnea

Obstructive sleep apnea (OSA) is linked to an increased mortality rate. However, the severity of individual obstruction events is rarely considered quantitatively in clinical practice. We hypothesized that OSA with especially severe obstruction events would predispose a patient to greater health risks than OSA with a similar apnea–hypopnea index (AHI), but lower severity of individual events. This hypothesis was tested in a follow‐up (198.2 ± 24.7 months) of a population of 1068 men referred for ambulatory polygraphic recording due to suspected OSA. The recordings were analysed according to the guidelines of the American Academy of Sleep Medicine. Furthermore, a novel obstruction severity parameter was determined; this was defined as the product of duration of the individual obstruction event and area of the related desaturation event. Patients treated with continuous positive airway pressure (CPAP) were omitted. We identified 125 deceased patients from our original population and for 113 of these a matching alive patient with similar AHI, age, body mass index (BMI), smoking habits and follow‐up time could be found. The deceased patients with severe OSA (based on conventional AHI) showed higher obstruction severity values than their AHI‐matched alive controls. Based on the multivariate logistic regression analysis, obstruction severity was the only parameter which was related statistically significantly to mortality in the severe OSA category. Furthermore, 59% of all deceased patients and 83% of those who had severe OSA displayed higher obstruction severity than the AHI‐matched alive counterparts. To conclude, the obstruction severity parameter provided valuable prognostic information supplementing AHI. The obstruction severity parameter might improve recognition of the patients with the highest risk.     

Autonomic markers of arousal during sleep in patients undergoing investigation for obstructive sleep apnoea, their relationship to EEG arousals, respiratory events and subjective sleepiness

Estimating the degree of sleep fragmentation is an important part of a respiratory sleep study and is conventionally measured using EEG micro arousals or is inferred indirectly from respiratory abnormalities such as apnoeas and desaturations. There is a need for less labour-intensive measures of sleep fragmentation, and transient rises in blood pressure and heart rate may fulfil this role. Forty unselected sleep clinic referrals undergoing investigation for possible obstructive sleep apnoea (OSA) were studied with one night of polysomnography. Three conventional indices of sleep fragmentation (EEG micro arousals, apnoea/hypopnoea index (AHI) and oxygen saturation dip rate (SaO₂ dips)) and two autonomic indices (heart rate and blood pressure rises) have been compared. Correlations between these five indices ranged from r=0.38 to r=0.73. Of the two autonomic indices, the correlations for blood pressure rises with SaO₂ dips and EEG micro arousals were stronger (r=0.71 and r=0.65, respectively) than those for heart rate rises (0.55 and 0.51). All indices of sleep fragmentation, apart from heart rate rises, were similar in their correlation with subjective sleepiness (r-values 0.21–0.36). Arousals implied from blood pressure rises (using pulse transit time) can be measured easily, are objective, and appear no worse at predicting subjective sleepiness than either EEG micro arousals or AHI. They may therefore provide a useful alternative to manual scoring of micro arousals from the EEG as an index of sleep fragmentation in sleep clinic patients undergoing investigation for possible OSA.     

Chemoreflex control of ventilation is altered during wakefulness in humans with OSA

We hypothesized that patients with obstructive sleep apnea (OSA) have a different awake ventilatory response to carbon dioxide above and below eupnea compared with normal. Eight male subjects with OSA and control subjects matched for gender, race, age, height and weight voluntarily hyperventilated during wakefulness to reduce the partial pressure of carbon dioxide (PET(CO2)) below 25 mmHg. Subjects were then switched into a rebreathing bag containing a normocapnic (42 mmHg) hypoxic [partial pressure of end tidal oxygen (PET(O2))=50 mmHg (H50)] or hyperoxic [PET(O2)=140 mmHg (H140)] gas mixture. During the trial PET(CO2) increased while PET(O2) was maintained at a constant level. The point at which ventilation and PET(CO2) increased linearly was considered to be the carbon dioxide ventilatory recruitment threshold (VRT(CO2)). Measurements of ventilation and its components (i.e. tidal volume and breathing frequency) were made below this threshold and the slope of the minute ventilation; tidal volume or breathing frequency response above the threshold was determined. Four trials for a given oxygen level were completed. The PET(CO2) that demarcated the VRT(CO2) was increased (H(50)=43.43+/-0.92 vs. 41.05+/-0.67; H(140)=47.65+/-0.80 vs. 45.28+/-0.75), as were measures of ventilation below the threshold (H(50)=18.50+/-2.11 vs. 13.44+/-1.43; H(140)=19.66+/-2.71 vs. 10.83+/-1.24) in the OSA subjects compared with control. In contrast the OSA and control subjects did not respond differently to changes in PET(CO2) above the threshold. We conclude that the PET(CO2) that delineates the VRT(CO2) and ventilation below this threshold is elevated in subjects with OSA.     

Estimating daytime sleepiness with previous night electroencephalography,electrooculography, and electromyography spectrograms in patients with suspected sleep apnea using a convolutional neural network

A common symptom of obstructive sleep apnea (OSA) is excessive daytime sleepiness (EDS). The gold standard test for EDS is the multiple sleep latency test (MSLT). However, due to its high cost, MSLT is not routinely conducted for OSA patients and EDS is instead evaluated using sleep questionnaires. This is problematic however, since sleep questionnaires are subjective and correlate poorly with the MSLT. Therefore, new objective tools are needed for reliable evaluation of EDS. The aim of this study was to test our hypothesis that EDS can be estimated with neural network analysis of previous night polysomnographic signals. We trained a convolutional neural network (CNN) classifier using electroencephalography, electrooculography, and chin electromyography signals from 2,014 patients with suspected OSA. The CNN was trained to classify the patients into four sleepiness categories based on their mean sleep latency (MSL); severe (MSL < 5min), moderate (5 ≤ MSL < 10), mild (10 ≤ MSL < 15), and normal (MSL ≥ 15). The CNN classified patients to the four sleepiness categories with an overall accuracy of 60.6% and Cohen’s kappa value of 0.464. In two-group classification scheme with sleepy (MSL < 10 min) and non-sleepy (MSL ≥ 10) patients, the CNN achieved an accuracy of 77.2%, with sensitivity of 76.5%, and specificity of 77.9%. Our results show that previous night’s polysomnographic signals can be used for objective estimation of EDS with at least moderate accuracy. Since the diagnosis of OSA is currently confirmed by polysomnography, the classifier could be used simultaneously to get an objective estimate of the daytime sleepiness with minimal extra workload.     

Behavioral Correlates of Sleep-Disordered Breathing in Older Men

Study Objectives:

To examine the association between sleep-disordered breathing (SDB) and subjective measures of daytime sleepiness, sleep quality, and sleep-related quality of life in a large cohort of community-dwelling older men and to determine whether any association remained after adjustment for sleep duration.

Design:

Cross-sectional. The functional outcome measures of interest were daytime sleepiness (Epworth Sleepiness Scale, ESS), sleep-related symptoms (Pittsburgh Sleep Quality Index, PSQI), and sleep-related quality of life (Functional Outcomes of Sleep Questionnaire, FOSQ). Analysis of variance and adjusted regression analyses examined the association between these outcome measures and SDB severity and actigraphy-determined total sleep time (TST). We then explored whether associations with SDB were confounded by sleep duration by adjusting models for TST.

Setting:

Community-based sample in home and research clinic settings.

Participants:

Two-thousand eight-hundred forty-nine older men from the multicenter Osteoporotic Fractures in Men Study that began in 2000. All participants underwent in-home polysomnography for 1 night and wrist actigraphy for a minimum of 5 consecutive nights.

Interventions:

N/A.

Measurements and Results:

Participants were aged 76.4 ± 5.5 years and had an apnea-hypopnea index (AHI) of 17.0 ± 15.0. AHI and TST were weakly correlated. ESS scores individually were modestly associated with AHI and TST, but the association with AHI was attenuated by adjustment for TST. PSQI and FOSQ scores were largely not associated with measures of SDB severity but were modestly associated with TST.

Conclusions:

Daytime sleepiness, nighttime sleep disturbances, and sleep-related quality of life were modestly associated with TST. After adjustment for TST, there was no independent association with SDB severity. These results underscore the potential differences in SDB functional outcomes in older versus young and middle-aged adults.

Citation:

Kezirian EJ; Harrison SL; Ancoli-Israel S; Redline S; Ensrud K; Goldberg AN; Claman DM; Spira AP; Stone KL. Behavioral correlates of sleep-disordered breathing in older men. SLEEP 2009;32(2):253–261.     

Effects of a lifestyle intervention on REM sleep‐related OSA severity in obese individuals with type 2 diabetes

The aim of this study was to determine if an intensive lifestyle intervention (ILI) reduces the severity of obstructive sleep apnea (OSA) in rapid‐eye movement (REM) sleep, and to determine if longitudinal changes in glycaemic control are related to changes in OSA severity during REM sleep over a 4‐year follow‐up. This was a randomized controlled trial including 264 overweight/obese adults with type 2 diabetes (T2D) and OSA. Participants were randomized to an ILI targeted to weight loss or a diabetes support and education (DSE) control group. Measures included anthropometry, apnea–hypopnea index (AHI) during REM sleep (REM‐AHI) and non‐REM sleep (NREM‐AHI) and glycated haemoglobin (HbA1c) at baseline and year 1, year 2 and year 4 follow‐ups. Mean baseline values of REM‐AHI were significantly higher than NREM‐AHI in both groups. Both REM‐AHI and NREM‐AHI were reduced significantly more in ILI versus DSE, but these differences were attenuated slightly after adjustment for weight changes. Repeated‐measure mixed‐model analyses including data to year 4 demonstrated that changes in HbA1c were related significantly to changes in weight, but not to changes in REM‐AHI and NREM‐AHI. Compared to control, the ILI reduced REM‐AHI and NREM‐AHI during the 4‐year follow‐up. Weight, as opposed to REM‐AHI and NREM‐AHI, was related to changes in HbA1c. The findings imply that weight loss from a lifestyle intervention is more important than reductions in AHI for improving glycaemic control in T2D patients with OSA.     

Sleep‐disordered breathing in children with mucolipidosis

Mucolipidosis (ML) is a rare lysosomal storage disorder with a wide spectrum of disease severity according to the type. Sleep‐disordered breathing is recognized as a characteristic feature of ML but objective data are scarce. The aim of the study was to describe sleep data and medical management in children with ML α/β. All patients with ML α/β followed at a national reference center of ML were included. Five patients had ML II, one patient had ML III and one patient had ML II‐III. One patient was started on noninvasive ventilation (NIV) to allow extubation after prolonged invasive mechanical ventilation. The six other patients underwent sleep study at a median age of 1.8 years (range 4 months–17.4 years). Obstructive sleep apnea (OSA) was observed in all patients with a median apnea‐hypopnea index (AHI) of 36 events/hr (range 5–52) requiring continuous positive airway pressure (CPAP) or NIV. CPAP/NIV resulted in an improvement of nocturnal gas exchange and was continued in all patients with an excellent compliance. Two patients died. Systematic sleep studies are recommended at time of diagnosis in ML. CPAP or NIV are effective treatments of OSA, well tolerated, and may contribute to improve the quality of life of patients and caregivers.     

Total duration of apnea and hypopnea events and average desaturation show significant variation in patients with a similar apnea–hypopnea index

Obstructive sleep apnea (OSA) is commonly diagnosed based on the apnea-hypopnea index (AHI). Presently, novel indices were introduced for sleep apnea severity: total duration of sleep apnea and hypopnea events (TAHD%) and a combined index including duration and severity of the events (TAHD% × average desaturation). Two hundred and sixty-seven subjects were divided based on their AHI into four categories (normal, mild, moderate, severe OSA). In the most severe cases TAHD% exceeded 70% of the recorded time. This is important as excessive TAHD% may increase mortality and cerebro-vascular complications. Moreover, simultaneous increase in duration and frequency of apnea and hypopnea events leads to a paradoxical situation where AHI cannot increase along severity of the disease. Importantly, the combined index including duration and severity of the events showed significant variation between patients with similar apnea-hypopnea indices. To conclude, the present results suggest that the novel parameters could give supplementary information to AHI when diagnosing the severity of OSA.     

Using tracheal breathing sounds and anthropometric information for screening obstructive sleep apnoea during wakefulness

Obstructive sleep apnoea (OSA) is a common yet underdiagnosed disorder. Undiagnosed OSA significantly increases perioperative morbidity and mortality for OSA patients undergoing surgery, requiring full anaesthesia. Tracheal breathing sounds characteristics during wakefulness have shown a high correlation with the apnoea–hypopnea index (AHI), while they are also affected by the anthropometric parameters, e.g., sex, age, etc. This study investigates the effects of the anthropometric parameters on our new quick objective OSA screening tool during wakefulness. Breathing sounds of 122 individuals (71 with AHI <15 as non-OSA and 51 with AHI?>?15 as OSA) were recorded during wakefulness in the supine position. The spectra and bi-spectra of 81 (47 non-OSA) individuals’ signals, which were randomly selected, were analysed as a training dataset to extract the most significant features with the lowest sensitivity to the anthropometric parameters. Using a support vector machine (SVM) classifier, these features resulted in 72.1, 64.7 and 77.5% testing classification accuracy, sensitivity and specificity, respectively. We also investigated classifying subjects into subgroups related to each anthropometric parameter and incorporating a voting procedure. This routine resulted in 83.6, 74.5 and 90.1% testing classification accuracy, sensitivity and specificity, respectively. In conclusion, it is possible to positively utilise the anthropometric information to enhance the classification accuracy for a reliable OSA screening procedure during wakefulness.     

Sleepiness and residual sleepiness in adults with obstructive sleep apnea

Sleepiness is a common, but not necessary symptom of the obstructive sleep apnea syndrome (OSA) and is a frequent chief complaint of patients with OSA who seek medical attention. While sleepiness may seem simple in nature, the underlying mechanisms producing daytime sleepiness in OSA are complex and poorly characterized. Moreover, the meaningful assessment of pathological sleepiness is frequently far from straightforward. Effective treatment of OSA is generally expected to resolve or ameliorate daytime sleepiness. An unknown percentage of treated OSA patients, however, remain sleepy during waking hours. The assessment and treatment of residual sleepiness in treated OSA can range from simple to difficult, depending on the nature and causes of the continued sleepiness. Recently, however, data from clinical trials have been generated which provide direction in the evaluation and management of the OSA patient suffering residual daytime sleepiness.     

Sleep state distribution of obstructive events in children: is obstructive sleep apnoea really a rapid eye movement sleep‐related condition?

Obstructive sleep apnoea (OSA) in children is commonly considered to occur predominantly in rapid eye movement (REM) sleep, but clinical experience suggests that this is not universally the case. We hypothesized that there would be a subgroup of children with OSA who have non‐REM (NREM) predominance of obstructive events and that these children share certain clinical characteristics. Thus, we aimed to compare the obstructive apnoea–hypopnoea index (OAHI) in REM versus NREM sleep and to assess factors influencing the distribution of events by sleep state. Polysomnography (PSG) recordings of 102 children aged 0–18 years with moderate to severe OSA (OAHI ≥5 h^?1) were reviewed. OAHI was calculated separately for REM and NREM sleep. A REM predominance index (RPI) was determined using log transformation [RPI = log (REM OAHI + 0.5) ? log (NREM OAHI + 0.5)] and compared with possible influencing factors using multiple linear regression. Analysis showed that obstructive events were more common in REM sleep (median REM OAHI 21.4 h^?1, median NREM OAHI 8.3 h^?1, P < 0.001). Mean RPI was significantly greater than zero (P = 0.003). However, a substantial minority of children (30.4%) had a higher NREM than REM OAHI. The factors that were related significantly to NREM predominance were older age (P = 0.02), higher arousal index (P < 0.001) and higher SpO₂ nadir (P < 0.001). Our findings demonstrate that while OSA is a REM sleep‐related problem in the majority of children, there is a significant subset of children with NREM predominance of obstructive events. This finding highlights the importance of considering sleep state distribution of events in studies of the pathophysiology and outcomes of OSA in childhood.     

Metrics of sleep apnea severity: beyond the apnea-hypopnea index

Obstructive sleep apnea (OSA) is thought to affect almost 1 billion people worldwide. OSA has well established cardiovascular and neurocognitive sequelae, although the optimal metric to assess its severity and/or potential response to therapy remains unclear. The apnea-hypopnea index (AHI) is well established; thus, we review its history and predictive value in various different clinical contexts. Although the AHI is often criticized for its limitations, it remains the best studied metric of OSA severity, albeit imperfect. We further review the potential value of alternative metrics including hypoxic burden, arousal intensity, odds ratio product, and cardiopulmonary coupling. We conclude with possible future directions to capture clinically meaningful OSA endophenotypes including the use of genetics, blood biomarkers, machine/deep learning and wearable technologies. Further research in OSA should be directed towards providing diagnostic and prognostic information to make the OSA diagnosis more accessible and to improving prognostic information regarding OSA consequences, in order to guide patient care and to help in the design of future clinical trials.     

Sleep-disordered breathing and cardio- and cerebrovascular diseases: 2003 update of clinical significance and future perspectives

Summary The purpose of this review is to summarize current knowledge about the link between sleep-disordered breathing (SDB) and cardiovascular and cerebrovascular diseases. Obstructive sleep apnoea (OSA) is a well-established risk factor for systemic arterial hypertension, and its treatment with continuous positive airway pressure leads to a decrease in daytime and night-time blood pressure profiles. Pulmonary arterial hypertension occurs in 20–30% of OSA patients and is usually mild. It is not yet clear if OSA per se leads to pulmonary hypertension or if the coexistence of chronic obstructive pulmonary disease with daytime and/or sleep-related hypoxaemia is required to provoke a persistent rise in pulmonary artery pressure. Furthermore, OSA is associated with nocturnal cardiac arrhythmias, especially cyclical fluctuations of the heart rate in response to recurrent apnoeas. Atrioventricular conduction blocks and ventricular premature beats are less often observed and seem to be confined to patients with severe OSA and those with accompanying ischaemic heart disease. The association between OSA and vaso-occlusive disease (i.e. atherosclerosis) is less clear. However, accumulating experimental and epidemiological data support such a link. Thus, OSA may lead to coronary artery disease (CAD) and stroke by promoting atherosclerosis. Correspondingly, patients with CAD or acute stroke show a high prevalence of SDB. Cheyne–Stokes respiration (CSR) is a specific pattern of central sleep apnoea occurring in patients with advanced congestive heart failure (CHF). If present, CSR clearly has a negative impact on the clinical course of CHF. Although the optimal treatment strategy for CSR is less well defined than that for OSA, the successful reversal of CSR might increase overall survival in affected patients.     

Comparing the neurocognitive effects of 40 h sustained wakefulness in patients with untreated OSA and healthy controls

We hypothesized that individuals with untreated obstructive sleep apnea (OSA) would exhibit greater vulnerability to sleep deprivation than healthy controls, due to the additional neurobiological 'load' of chronic sleep fragmentation. After baseline sleep with 8 h time in bed, participants remained awake for 40 h. Psychomotor Vigilance Task (PVT, mean slowest 10% 1/RT), AusEd Driving Simulator task (steering and speed deviation), and subjective sleepiness (Karolinska Sleepiness Scale, KSS) were assessed every 2 h. Nonlinear mixed-effects models were used to characterize individual differences in baseline/average performance, the linear effect of increasing hours awake, circadian amplitude and phase. Eight participants with untreated OSA with mean (SD) age 44.6 (8.4), apnea–hypopnea index (AHI) 49.8 (24.7), Epworth Sleepiness Scale (ESS) 11.9 (4.8) and nine healthy controls age 27.8 (3.7), AHI 4.5 (2.7), ESS 7.3 (2.1) completed the protocol. Baseline KSS was significantly higher (1.4 units, P  = 0.03) in the OSA group and there was a trend toward lower baseline speed deviation on the AusEd ( P  = 0.05). After adjusting for the significant effects of accumulated time awake, circadian amplitude and phase (all P  < 0.005), there was no difference in performance decrements between those with and without sleep apnea in PVT, driving simulator performance and subjective sleepiness ( P  > 0.5). Random-effects modeling confirmed the presence of significant inter-individual variability in vulnerability to sleep deprivation. Patients with OSA did not respond differently to sleep deprivation than healthy controls. As expected, total sleep deprivation led to significant worsening in performance and subjective sleepiness in both groups.     

Sleep-disordered breathing in heart failure: characteristics and implications

Sleep-disordered breathing, namely obstructive sleep apnea (OSA) and central sleep apnea (CSA), are both often encountered in the setting of heart failure (HF), and have distinct differences in terms of prevalence, pathophysiology and consequences. OSA is independently associated with an increased risk for cardiovascular disease and for congestive HF in the general population. It is conceivable that this breathing disorder may have particularly deleterious effects in patients with coexisting heart disease, especially in those with a failing heart. There are considerable data addressing the interaction between OSA and the cardiovascular system, which underscore the importance of an early detection of this breathing disorder, especially in patients with HF. CSA is generally considered a consequence rather than a cause of HF, and is correlated with the severity of hemodynamic impairment. However, when present, it is associated with increased arrhythmic risk and higher cardiac mortality. Potential mechanisms implicated in the genesis of this breathing pattern and the possible therapeutic options, which have been proven to be effective in the clinical setting, are discussed.