Relationship between sodium intake and sleep apnea in patients with heart failure

Roles of vitamins and nutrition in obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder, with a prevalence that rises alongside with the increasing prevalence of obesity. OSA is characterized by a low-inflammatory state and is followed by cardiovascular and metabolic sequelae. Continuous positive airway pressure (CPAP) represents the cornerstone of treatment for severe OSA. However, poor compliance with CPAP treatment renders OSA treatment a challenging venture. Weight loss and exercise are recommended as adjunctive treatment options for OSA. Several diets have proven to facilitate weight loss, and to alleviate the inflammatory status in patients with OSA. Moreover, several vitamins exhibit antioxidant properties that beneficially affect OSA pathology and reduce the risk of cardiovascular complications.

AREA COVERED

This narrative review aims to summarize the current knowledge regarding the effect of nutrition and vitamin deficiencies on OSA. Included were publications, relevant to the topic, with different types of design (i.e. cross-sectional studies, cohort studies, clinical trials, systematic reviews, meta-analyses, etc.) and indexed in PubMed database until 31 March 2024.

EXPERT OPINION

In addition to weight loss, other food components, such as proteins, carbohydrates, anti-inflammatory agents, vitamins A, B, C, D, E, and sodium, may play a beneficial role in the incidence and severity of OSA.

Diet and sleep quality in chilean university students

OBJECTIVES

To evaluate an association between eating patterns and sleep quality in Chilean university students.

METHODS

A cross-sectional analytical study was conducted. Participants included students from 4 Chilean universities. Each student was administered survey Questionnaire on the frequency of healthy and unhealthy eating habits and Pittsburgh Sleep Quality Index and their weight and height were taken to obtain the Body Mass Index (BMI).

RESULTS

A total of 1,079 young university students, 80.26 % were women and the average age was 21.7 years. The 73.68 % have inadequate sleep quality. There is a significant differences in frequency between sleep quality and the intake of breakfast (p<0.001), fish (p<0.05) and dinner (p<0.05), that is, university students who reported optimal sleep consume breakfast and dinner on a daily basis and their fish intake is in line with nutritional recommendations. With respect to the association between sleep quality and healthy dietary patterns, it is observed a significant association (p<0.01) between optimal sleep and daily breakfast consumption in model 3 (Odds Ratio (OR): 0.61 (0.46-0.82)). Regarding unhealthy dietary patterns, a significant association (p<0.05) is observed in model 3 between sleep quality and alcohol consumption (OR: 1.42 (1.02-1.96)). Furthermore, a significant association between optimal sleep and salt consumption is observed in both model 2 (OR: 0.73 (0.54-0.99)) and model 3 (OR: 0.72 (0.53-0.97)). Finally, a significant relationship between not tobacco use and optimal sleep is observed (OR: 0.68 (0.48-0.96)).

CONCLUSION

A positive relationship between healthy diet and sleep quality was observed in university students, which certain dietary patterns, such as the consumption of breakfast and low salt consumption and alcohol, are crucial to talk about a good sleep quality in this population group.

Comorbidity of patients with noncommunicable diseases in general practice. Eurasian guidelines

Создание руководства поддержано Советом по терапевтическим наукам отделения клинической медицины Российской академии наук.

Impact of Body Composition on Sleep and Its Relationship with Sleep Disorders: Current Insights

Sleep is involved in many physiological processes and is essential for both physical and mental health. Obesity and sleep deprivation due to sleep disorders are major public health issues. Their incidence is increasing, and they have a wide range of adverse health-related consequences, including life-threatening cardiovascular disease. The impact of sleep on obesity and body composition is well-known, and many studies have shown an association between insufficient or excessive sleep duration and obesity, body fat percentage, and weight gain. However, there is growing evidence of the effects of body composition on sleep and sleep disorders (particularly sleep disordered breathing) through anatomical and physiological mechanisms (nocturnal fluid shift, core body temperature, or diet). Although some research has been conducted on the bidirectional effects of sleep-disordered breathing and body composition, the specific effects of obesity and body composition on sleep and the underlying mechanisms that explain these effects remain unclear. Therefore, this review summarizes the findings on the effects of body composition on sleep and draws conclusions and proposals for future research in this field.

Eating habit of adding salt to foods and incident sleep apnea: a prospective cohort study

BACKGROUND

Previous studies have revealed that sodium-restricted diet intervention significantly decreased apnea frequency among patients with sleep apnea. However, the longitudinal association between the habit of adding salt to foods and sleep apnea in general populations is uncertain.

METHODS

The UK Biobank cohort study includes more than 500,000 participants aged 40 to 69 across the United Kingdom from 2006 to 2010. The frequency of adding salt to foods was collected through a touch screen questionnaire. Incident sleep apnea was ascertained by hospital inpatient records, death registries, primary care, and self-reported diagnosis. The association between the habit of adding salt to foods and incident sleep apnea was estimated using Cox proportional hazard regression models.

RESULTS

Among the 488,196 participants (mean age 56.5 years; 55.0% female) in this study. During a median follow-up of 12.3 years, 6394 sleep apnea events occurred. Compared to participants who never/rarely added salt to foods, those who sometimes, usually, and always added salt to foods had an 11% (hazard ratio [HR] 1.11, 95% confidence interval [CI]: 1.04 to 1.17), 15% (HR 1.15, 95% CI: 1.07 to 1.24), and 24% (HR 1.24, 95% CI: 1.12 to 1.37) higher risk for incident sleep apnea, respectively.

CONCLUSIONS

In this large prospective study, the habit of adding salt to foods was associated with a higher risk of incident sleep apnea. The findings support the benefits of a salt reduction program in preventing sleep apnea.

Overall diet quality and proinflammatory diet in relation to risk of obstructive sleep apnea in 3 prospective US cohorts

BACKGROUND

Inflammation-related mechanisms may be important in the development of obstructive sleep apnea (OSA), and diet plays a crucial role in modulating inflammation. Current epidemiologic evidence for the associations between dietary patterns and OSA risk is limited to cross-sectional studies.

OBJECTIVES

We investigated prospectively the associations of overall diet quality and proinflammatory diet with OSA risk.

METHODS

We followed 145,801 participants in the Nurses' Health Study (NHS) (2002-2012), NHS II (1995-2013), and Health Professionals Follow-up Study (1996-2012). Alternative Healthy Eating Index 2010 (AHEI) and Empirical Dietary Inflammatory Pattern (EDIP) scores were calculated based on validated FFQs administered every 4 y. Cox models were used to estimate HRs and 95% CIs.

RESULTS

We documented 8856 incident OSA cases during follow-up. In pooled analyses adjusted for potential confounders, higher diet quality (higher AHEI scores) was associated with lower OSA risk (HR comparing the highest with the lowest quintile of AHEI: 0.76; 95% CI: 0.71, 0.82; P-trend < 0.001), and higher dietary inflammatory potential (higher EDIP scores) was associated with significantly increased risk (HR comparing the highest with the lowest quintile of EDIP: 1.94; 95% CI: 1.81, 2.08; P-trend < 0.001). Additional adjustment for metabolic factors attenuated both associations. The association with AHEI score was no longer statistically significant (comparable HR: 0.98; 95% CI: 0.91, 1.05; P-trend = 0.54), whereas the association with EDIP score remained statistically significant (comparable HR: 1.31; 95% CI: 1.22, 1.41; P-trend < 0.001).

CONCLUSIONS

A healthier diet, particularly one with anti-inflammatory potential, was associated with lower OSA risk.

Hypertension, Anxiety and Obstructive Sleep Apnea in Cardiovascular Disease and COVID-19: Mediation by Dietary Salt

This perspective paper used a grounded theory method to synthesize evidence proposing that sodium toxicity from excessive dietary salt intake is a potential common pathophysiological mechanism that mediates the association of hypertension, obstructive sleep apnea, and anxiety with cardiovascular disease and COVID-19. Increased anxiety in these conditions may be linked to a high-salt diet through stimulation of the sympathetic nervous system, which increases blood pressure while releasing catecholamines, causing a "fight or flight" response. A rostral shift of fluid overload from the lower to the upper body occurs in obstructive sleep apnea associated with COVID-19 and cardiovascular disease, and may be related to sodium and fluid retention triggered by hypertonic dehydration. Chronic activation of the renin-angiotensin-aldosterone system responds to salt-induced dehydration by increasing reabsorption of sodium and fluid, potentially exacerbating fluid overload. Anxiety may also be related to angiotensin II that stimulates the sympathetic nervous system to release catecholamines. More research is needed to investigate these proposed interrelated mechanisms mediated by dietary salt. Furthermore, dietary interventions should use a whole-food plant-based diet that eliminates foods processed with salt to test the effect of very low sodium intake levels on hypertension, anxiety, and obstructive sleep apnea in cardiovascular disease and COVID-19.

Bidirectional relationships of comorbidity with obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is frequently associated with comorbidities that include metabolic, cardiovascular, renal, pulmonary and neuropsychiatric. There is considerable evidence that OSA is an independent risk factor for many of these comorbidities but, more recently, there is evidence that some of these comorbidities may predispose to the development of OSA. Thus, there is growing evidence of a bidirectional relationship between OSA and comorbidity, especially for heart failure, metabolic syndrome and stroke. Potential mechanisms of bidirectional relationships differ in individual comorbidities with fluid retention and redistribution being especially important in heart failure and end-stage renal disease, whereas neural mechanisms may be more important in diabetes mellitus and stroke. The evidence for other comorbidities, such as hypertension and atrial fibrillation, support these being more a consequence of OSA with limited evidence to support a bidirectional relationship. The present review explores the evidence for such bidirectional relationships with a particular perspective on comorbidities that may predispose to OSA. The impact of therapy in bidirectional relationships is also reviewed, which highlights the clinical importance of accurate diagnosis. This aspect is especially true of COPD, where the identification of co-existing OSA has important implications for optimum therapy.

Obstructive sleep apnoea (OSA) is an independent risk factor for comorbidity, especially cardiometabolic. However, some comorbidities may be risk factors for OSA, supporting a bidirectional relationship that may have important implications for treatment.https://bit.ly/3BbJy6V

Obstructive Sleep Apnoea: Focus on Pathophysiology

Obstructive sleep apnoea (OSA) is characterized by recurring episodes of upper airway obstruction during sleep and the fundamental abnormality reflects the inability of the upper airway dilating muscles to withstand the negative forces generated within the upper airway during inspiration. Factors that result in narrowing of the oropharynx such as abnormal craniofacial anatomy, soft tissue accumulation in the neck, and rostral fluid shift in the recumbent position increase the collapsing forces within the airway. The counteracting forces of upper airway dilating muscles, especially the genioglossus, are negatively influenced by sleep onset, inadequacy of the genioglossus responsiveness, ventilatory instability, especially post arousal, and loop gain. Recent reports indicate that multiple endotypes reflecting OSA pathophysiology are present in individual patients. A detailed understanding of the complex pathophysiology of OSA encourages the development of therapies targeted at these pathophysiological endotypes and facilitates a move towards precision medicine as a potential alternative to continuous positive airway pressure therapy in selected patients.

Sleep Apnoea and Heart Failure

Heart Failure (HF) and Sleep-Disordered-Breathing (SDB) are two common conditions that frequently overlap and have been studied extensively in the past three decades. Obstructive Sleep Apnea (OSA) may result in myocardial damage, due to intermittent hypoxia increased sympathetic activity and transmural pressures, low-grade vascular inflammation and oxidative stress. On the other hand, central sleep apnoea and Cheyne-Stokes respiration (CSA-CSR) occurs in HF, irrespective of ejection fraction either reduced (HFrEF), preserved (HFpEF) or mildly reduced (HFmrEF). The pathophysiology of CSA-CSR relies on several mechanisms leading to hyperventilation, breathing cessation and periodic breathing. Pharyngeal collapse may result at least in part from fluid accumulation in the neck, owing to daytime fluid retention and overnight rostral fluid shift from the legs. Although both OSA and CSA-CSR occur in HF, the symptoms are less suggestive than in typical (non-HF related) OSA. Overnight monitoring is mandatory for a proper diagnosis, with accurate measurement and scoring of central and obstructive events, since the management will be different depending on whether the sleep apnea in HF is predominantly OSA or CSA-CSR. SDB in HF are associated with worse prognosis, including higher mortality than in patients with HF but without SDB. However, there is currently no evidence that treating SDB improves clinically important outcomes in patients with HF, such as cardiovascular morbidity and mortality.

Association of Sodium with Obstructive Sleep Apnea. The ELSA-Brasil Study

Rationale: Excessive sodium may have a role in the pathogenesis of obstructive sleep apnea (OSA) for patients with hypervolemic conditions, but it is unclear whether this is valid for all patients with OSA, including those with no significant comorbidities.Objectives: To test the association of urinary sodium and OSA in a large sample of participants from the ELSA-Brasil (Estudo Longitudinal de Saúde do Adulto-Brasil) Study. In addition, we stratified the analysis participants according to the presence of hypertension.Methods: In this cross-sectional study, OSA was defined by an apnea-hypopnea index ≥15 events/h. A validated 12-hour urine collection as representative of the 24-hour period was obtained from all participants to measure sodium excretion. We performed a logistic regression analysis to test the association of urinary sodium excretion with OSA (dependent variable) adjusting for age, sex, race and income, glomerular filtration rate, diabetes, physical activity, and antihypertensive classes related to sodium excretion. To address potential residual factors that may influence sodium excretion, we performed additional analysis replacing sodium excretion for salt intake (food frequency questionnaire) using the same models.Results: We studied 1,946 participants (age 49 ± 8 yr; 43.4% men). A third of them had OSA. Compared with those with no OSA, participants with OSA presented with higher sodium excretion (1.66 [1.19-2.29] vs. 1.99 [1.44-2.69] g/12 h; P < 0.001). After adjustments for confounding factors, we found no overall significant associations of sodium excretion with OSA (odds ratio [OR], 1.09; 95% confidence interval [CI], 0.97-1.23; P = 0.150). Regardless of the OSA status, the sodium excretion was higher in hypertensive than in normotensive participants (1.93 [1.35-2.64] vs. 1.71 [1.22-2.37] g/12 h). An independent association of sodium excretion with OSA was observed in patients with hypertension only (OR, 1.326; 95% CI, 1.067-1.648; P = 0.011), but the interaction of urinary sodium with hypertension was not significant (P = 0.37). The analysis of salt intake revealed consistent findings.Conclusions: The potential role of sodium in the pathogenesis of OSA seems to be modest and limited for those with higher salt intake and, consequently, higher fluid retention such as observed in patients with hypertension.

Relationship between salt intake and sleep disordered breathing in dialysis patients

BACKGROUND

The prevalence of sleep disordered breathing is high in patients with end-stage renal disease. Salt intake is related to the severity of obstructive sleep apnea in patients with resistant hypertension and hyperaldosteronism. We investigated the relationship between salt intake and sleep disordered breathing in patients on maintenance hemodialysis.

PATIENTS AND METHODS

We studied 128 dialysis outpatients (mean age 63 ± 11 years) who were followed at Kokura Daiichi Hospital. We estimated each patient's salt intake using an InBody S10 body composition analyzer and measured the 3% oxygen desaturation index (ODI) during sleep using a Pulsewatch: PMP-200 GplusX.

RESULTS

The average estimated salt intake was 8.0 ± 2.6 g/day, and the median value of that was 7.5 g/day. Blood pressure (BP) before and after dialysis were 140 ± 18/78 ± 11 and 127 ± 13/72 ± 8 mmHg, respectively. The geometric average number of 3% ODI was 7.1, and sleep disordered breathing was detected in 30% of all subjects. The patients with ≥ 7.5 g/day salt intake were younger and more frequently male and had higher body mass index (BMI) and BP before dialysis compared to those with salt intakes < 7.5 g/day. Patients with ≥ 7.5 g/day salt intake had a significantly higher geometric average number of 3% ODI; however, this relationship became weaker after adjusting for BMI. The same relationship was obtained for the prevalence of sleep disordered breathing.

CONCLUSION

The prevalence of sleep disordered breathing in patients on maintenance hemodialysis was high, and the sleep disordered breathing was associated with salt intake and BMI.

Dietary Factors and Sleep Quality Among Hemodialysis Patients in Malaysia

OBJECTIVES

Poor sleep quality is a commonly seen problem in hemodialysis patients. This study investigated the associations between dietary factors and sleep quality among hemodialysis patients.

DESIGN AND METHODS

This is a cross-sectional study conducted among 184 eligible hemodialysis patients at four dialysis units in Malaysia. Three days dietary recall were used in the analysis of dietary intake and behavior. Sleep quality was assessed through Pittsburgh Sleep Quality Index.

RESULTS

More than half of the patients were poor sleepers. Among the sleep components, sleep latency affected patients the most, with the use of sleep medications was relatively low. A majority of the patients had inadequate dietary intake of energy (88%) and protein (75%). Dietary protein, potassium adjusted for body weight, and sodium intake were significantly increased in poor sleepers. Lower percentage of energy from carbohydrates; higher percentage of energy from fats; higher intakes of dietary protein, fat, phosphorus, and sodium were correlated with poorer sleep quality and its components. Skipping dinner on non-dialysis days and having supper on dialysis days were associated with poor sleep quality.

CONCLUSION

Poor sleep is prevalent among hemodialysis patients. Sleep quality of hemodialysis patients was highly associated with certain dietary factors. Periodical assessment of sleep quality and dietary intake is necessary to identify poor sleepers with inappropriate dietary intake to allow effective clinical and nutritional interventions to improve the sleep quality and nutritional status of these patients.

From Brain to Blood Vessel: Insights From Muscle Sympathetic Nerve Recordings: Arthur C. Corcoran Memorial Lecture 2020

Multiunit recordings of postganglionic sympathetic outflow to muscle yield otherwise imperceptible insights into sympathetic neural modulation of human vascular resistance and blood pressure. This Corcoran Lecture will illustrate the utility of microneurography to investigate neurogenic cardiovascular regulation; review data concerning muscle sympathetic nerve activity of women and men with normal and high blood pressure; explore 2 concepts, central upregulation of muscle sympathetic outflow and cortical autonomic neuroplasticity; present sleep apnea as an imperfect model of neurogenic hypertension; and expose the paradox of sympathetic excitation without hypertension. In awake healthy normotensive individuals, resting muscle sympathetic nerve activity increases with age, sleep fragmentation, and obstructive apnea. Its magnitude is not signaled by heart rate. Age-related changes are nonlinear and differ by sex. In men, sympathetic nerve activity increases with age but without relation to their blood pressure, whereas in women, both rise concordantly after age 40. Mean values for muscle sympathetic nerve activity burst incidence are consistently higher in cohorts with hypertension than in matched normotensives, yet women's sympathetic nerve traffic can increase 3-fold between ages 30 and 70 without causing hypertension. Thus, increased sympathetic nerve activity may be necessary but is insufficient for primary hypertension. Moreover, its inhibition does not consistently decrease blood pressure. Despite a half-century of microneurographic research, large gaps remain in our understanding of the content of the sympathetic broadcast from brain to blood vessel and its specific individual consequences for circulatory regulation and cardiovascular, renal, and metabolic risk.

SLEEP APNEA IN GOUT PATIENTS: UNDERLYING MECHANISMS AND SHARED PATIENT SUBTYPES

Acute and chronic inflammation in gout causes permanent tissue damage, leads to restricted mobility and significantly reduces the quality of life. Obstructive sleep apnea (OSA) is a breath disordered sleep disease, which is a risk factor for respiratory, cardiovascular and cerebrovascular complications, nephropathy and other diseases. The aim of this paper was to explore the underlying mechanisms and shared pathways, targets and biomarkers of sleep apnea and gout. aiming at providing clear evidence about whether OSAS patients have higher serum uric acid levels and more susceptible to gout. Materials and methods. We conducted this literature analysis on relevant studies, which were identified via electronic databases from inception to May 30, 2020. Study selection was conducted according to predesigned criteria, and two authors independently extracted data from included studies. Results. In the period from 2010 to 2020, 4 large-scale population-based studies were conducted to prove that OSA can affect the level of uric acid, resulting in increased incidence of gout in OSA patients. Only one big population-based study during 2010-2020 assessed the development of OSA against the background of gout. The data from these studies showed an undoubted relationship between the two diseases, but to date it is not completely known how much it is due to common risk factors and how interlinked the development mechanisms are. Conclusions. Relationship between OSA, gout, and pro-inflammatory/metabolic disorders is therefore complex; with some recent studies indicate different mechanisms may play a role in the development of OSA-gout combination. The inconsistency in results may indicate the presence of several patient profiles or subtypes with gout-OSA comorbidity: combined with metabolic syndrome (most common), combined with renal dysfunction without obesity, and others (dietary violations, genetic diseases, acidosis). This paper reviews the research progress on the relationship between the epidemiological characteristics of OSA and the incidence of gout, with the insight into pathogenetic mechanisms of comorbidity.

Adherence to a Dietary Approach to Stop Hypertension (DASH)-Style in Relation to Daytime Sleepiness

BACKGROUND

The beneficial impact of adherence to a DASH diet on several metabolic conditions and psychological well-being has been shown previously. Dietary modification can affect sleep quality. Thus, the aim of this present study was to investigate the correlation between adherence to the DASH diet and daytime sleepiness score in adolescent girls.

METHODS

A total of 535 adolescent girls aged between 12 and 18 years old were recruited from different regions of Khorasan Razavi in northeastern of Iran, using a random cluster sampling method. DASH scores were determined according to the method of Fung et al. A Persian translation of the Epworth Sleepiness Scale (ESS-IR) was used to assess of daytime sleepiness. To investigate the correlation between DASH-style diet and daytime sleepiness score, we applied logistic regression analysis in crude and adjusted models.

RESULTS

As may be expected, participants with the greatest adherence to the DASH diet had significantly higher intakes of fruits, vegetables, low-fat dairy products, fish and nuts, and lower consumption of refined grains, red and processed meat, sugar-sweetened beverages and sweets. There was an inverse correlation between adherence to the DASH-style diet and scores for daytime sleepiness in crude model (β= -0.12; P=0.005). These findings were remained significant after adjustment for confounding variables (β= -0.08 P=0.04).

CONCLUSION

There is an inverse correlation between adherence to DASH diet and daytime sleepiness score. Further studies, particularly longitudinal studies, are required to determine whether dietary intervention may improve daytime sleepiness.

Sleep Apnea and Cardiovascular Disease: An Enigmatic Risk Factor

Synchronization of molecular, metabolic, and cardiovascular circadian oscillations is fundamental to human health. Sleep-disordered breathing, which disrupts such temporal congruence, elicits hemodynamic, autonomic, chemical, and inflammatory disturbances with acute and long-term consequences for heart, brain, and circulatory and metabolic function. Sleep apnea afflicts a substantial proportion of adult men and women but is more prevalent in those with established cardiovascular diseases and especially fluid-retaining states. Despite the experimental, epidemiological, observational, and interventional evidence assembled in support of these concepts, this substantial body of work has had relatively modest pragmatic impact, thus far, on the discipline of cardiology. Contemporary estimates of cardiovascular risk still are derived typically from data acquired during wakefulness. The impact of sleep-related breathing disorders rarely is entered into such calculations or integrated into diagnostic disease-specific algorithms or therapeutic recommendations. Reasons for this include absence of apnea-related symptoms in most with cardiovascular disease, impediments to efficient diagnosis at the population level, debate as to target, suboptimal therapies, difficulties mounting large randomized trials of sleep-specific interventions, and the challenging results of those few prospective cardiovascular outcome trials that have been completed and reported. The objectives of this review are to delineate the bidirectional interrelationship between sleep-disordered breathing and cardiovascular disease, consider the findings and implications of observational and randomized trials of treatment, frame the current state of clinical equipoise, identify principal current controversies and potential paths to their resolution, and anticipate future directions.

The relationship between adherence to a Dietary Approach to Stop Hypertension (DASH) dietary pattern and insomnia

BACKGROUND

Adherence to a DASH- style diet has been reported to be associated with several health-related outcomes. A limited number of reports suggest that diet is an important behavioral determinant of insomnia. The current study aimed to explore the relationship between adherence to a DASH diet and the prevalence of insomnia in adolescent girls.

METHODS

A total of 488 adolescent girls aged 12-18 years old were recruited from different regions of Khorasan Razavi in northeastern of Iran, using a random cluster sampling method. DASH scores were determined according to the method of Fung et al. A validated Iranian version of the Insomnia Severity Index questionnaire was used to assess sleep insomnia. To assess the association between the DASH dietary pattern and insomnia, we applied logistic regression analysis in crude and adjusted models.

RESULTS

As may be expected, participants in the upper quintile of the DASH diet had significantly higher intakes of fruits, vegetables, low fat dairy products, fish and nuts and lower consumption of refined grains, red and processed meat, sugar-sweetened beverages and sweets. We found that a high adherence to a DASH-style diet was associated with a lower odds of insomnia (OR: 0.51; 95% CI 0.26-1.00) compared with those with lowest adherence. Similar results were found after adjustment for potential confounders.

CONCLUSIONS

There is an inverse association between adherence to DASH dietary patterns and insomnia. Further prospective studies are required to demonstrate these findings.

Diuretic or sodium-restricted diet for obstructive sleep apnea-a randomized trial

Study Objectives

Interventions that decrease leg fluid retention reduce obstructive sleep apnea (OSA) severity in nonrandomized experiments. We aimed to investigate in a randomized trial the effect of interventions that reduce fluid volume on OSA severity.

Methods

Men diagnosed with severe OSA were randomized to receive daily spironolactone 100 mg + furosemide 20 mg or nutritional counseling to sodium-restricted diet plus placebo pill or placebo pill. All participants underwent home sleep apnea testing at baseline and after 1 week follow-up. The change in apnea-hypopnea index (AHI) was the primary outcome.

Results

The study included 54 participants and all were assessed at follow-up. The average baseline value of the AHI was similar among groups and from baseline to follow-up the AHI reduced 14.4 per cent (δ value -7.3 events per hour; 95% confidence interval, -13.8 to -0.9) in the diuretic group, 22.3 per cent (-10.7; 95% CI, -15.6 to -5.7) in the diet group, and 0.8 per cent (0.4; 95% CI, -2.5 to 3.2) in the placebo group (p = .001 for time × group interaction). None of the patients had their AHI returned to normal. The reduction in the total body water was 2.2 ± 2.2 L in the diuretic group (p < .001) and 1.0 ± 1.6 l in the low salt diet group (p = .002). Sleepiness and neck circumference were significantly reduced only in the diet group (p = .007 and p < .001 for the time × group interactions, respectively).

Conclusions

Interventions to reduce bodily fluid content in men with severe OSA promoted a limited decrease of apnea frequency. This finding suggests that rostral fluid displacement affects only partially the OSA severity and/or that other factors prevail in determining pharyngeal collapsibility.

Clinical Trial

Sodium-Restricted Diet and Diuretic in the Treatment of Severe Sleep Apnea (DESALT), https://clinicaltrials.gov/ct2/show/NCT01945801 ClinicalTrials.gov number: NCT01945801.

Temporal shifts in fluid in pulmonary hypertension with and without sleep apnea

Overnight extracellular rostral fluid shifts have been shown to be of importance in patients with fluid-retaining states and are associated with a higher prevalence of sleep apnea. Pulmonary hypertension is frequently associated with right ventricular dysfunction and progressive right ventricular failure, and an increased prevalence of sleep apnea has been described. In light of the importance of fluid shifts in the pathophysiology of sleep apnea, we aimed to explore temporal fluid shifts in patients with pulmonary hypertension with and without sleep apnea. Patients with pulmonary hypertension (WHO Group 1 or 4) had overnight extracellular rostral fluid shift assessment before and a minimum of 3 months after initiation of pulmonary hypertension-specific therapy. Fluid shift measurements of extracellular leg, abdominal, thoracic and neck fluid volumes were performed simultaneously. Twenty-nine patients with pulmonary hypertension (age 55 ± 16 years, 69% female) participated. Sleep apnea was diagnosed in 15 subjects (apnea-hypopnea index 14 [8-27] per hr). There were no significant differences in baseline or overnight leg extracellular rostral fluid, abdominal extracellular rostral fluid, thoracic extracellular rostral fluid or neck extracellular rostral fluid between those with and without sleep apnea. There was a significant inverse correlation between the sleep apnea severity and the overnight change in leg extracellular rostral fluid (r = -0.375, p = 0.049). There were no significant differences detected in overnight extracellular rostral fluid shifts from baseline to follow-up. Treatment-naïve patients with pulmonary hypertension both with and without sleep apnea demonstrate overnight extracellular rostral fluid shifts from the legs into the thorax and neck. Pulmonary hypertension-specific treatment, while significantly improving cardiac haemodynamics, had little impact on nocturnal extracellular rostral fluid shifts or the presence of sleep apnea.

What You Eat Could Affect Your Sleep: Dietary Findings in Patients With Newly Diagnosed Obstructive Sleep Apnea

Rationale. We hypothesized that certain dietary components such as increased fat intake are associated with severity of obstructive sleep apnea (OSA). Methods. A total of 104 patients, diagnosed with OSA completed a validated dietary survey. The apnea-hypopnea index (AHI) was used to measure the severity of OSA. Subjects were divided using body mass index (BMI) into obese and overweight categories. Regression analysis was performed to predict severity of OSA from gender, BMI, age, % energy from fat, and the individual dietary components of the survey. Results. Overweight subjects who ate a diet high in fat (>35% of their total diet) had twice the severity of sleep apnea (AHI 18.2 ± 10.1 vs 36.6 ± 27.5; P = .001). There was a strong trend (P = .056) in OSA severity between subjects eating processed meats "often" (AHI 42.5 ± 30.7) versus those eating "rarely/never" (AHI 28.9 ± 22.7). Eating greater than 2 servings of dairy daily was associated with worsening severity of OSA (AHI 26.2 ± 15.6 vs 39.7 ± 31; P = .04]. Conclusions. Dietary components such as fat intake and processed meats were associated with increased risk of OSA severity. In addition, 2 servings of dairy foods were associated with a decreased severity of OSA at presentation.

Fluid Redistribution in Sleep Apnea: Therapeutic Implications in Edematous States

Sleep apnea (SA), a condition associated with increased cardiovascular risk, has been traditionally associated with obesity and aging. However, in patients with fluid-retaining states, such as congestive heart failure and end-stage renal disease, both prevalence and severity of SA are increased. Recently, fluid shift has been recognized to play an important role in the pathophysiology of SA, since the fluid retained in the legs during the day shifts rostrally while recumbent, leading to edema of upper airways. Such simple physics, observed even in healthy individuals, has great impact in patients with fluid overload. Correction of the excess fluid volume has risen as a potential target therapy to improve SA, by attenuation of nocturnal fluid shift. Such strategy has gained special attention, since the standard treatment for SA, the positive airway pressure, has low compliance rates among its users and has failed to reduce cardiovascular outcomes. This review focuses on the pathophysiology of edema and fluid shift, and summarizes the most relevant findings of studies that investigated the impact of treating volume overload on SA. We aim to expand horizons in the treatment of SA by calling attention to a potentially reversible condition, which is commonly underestimated in clinical practice.

Significance of obstructive sleep apnea in the patient with pulmonary hypertension

PURPOSE OF REVIEW

The purpose of this review was to evaluate the consequence of obstructive sleep apnea (OSA) in pulmonary hypertension by reviewing the current literature and understanding potential pathophysiological mechanisms.

RECENT FINDINGS

Small studies have suggested a high prevalence of comorbid OSA in those with known pulmonary hypertension. Pathophysiological mechanisms are highly suggestive of potential deleterious effect of OSA on pulmonary hemodynamics.

SUMMARY

Clearly, current research work on comorbid OSA and pulmonary hypertension is still in its infancy and the field is ripe for future investigation. The significance of OSA in this population has yet to be fully determined.

Effect of diuretics and sodium-restricted diet on sleep apnea severity: study protocol for a randomized controlled trial

Background

Obstructive sleep apnea occurs as a result of increased collapsibility of the upper airway. Overnight fluid displacement from the legs to the neck causes pharyngeal narrowing and increased apnea severity. Sodium intake is associated with apnea severity. We hypothesized that interventions that decrease bodily fluid content might reduce the severity of sleep apnea.

Methods/design

This is a randomized clinical trial including men with an apnea-hypopnea index greater than 30 events/hour, previously diagnosed by full-night in-laboratory polysomnography. A total of 54 men will be included and randomly assigned to three groups: Diuretic (n = 18), sodium-restricted diet (n = 18), and control (n = 18). The intervention will last one week. Intention-to-treat and per-protocol analyses will be performed. The diuretic group will receive combined spironolactone 100 mg plus furosemide 20 mg daily, taken in the morning. The diet group will receive a regimen with a maximum intake of 3 g of sodium per day. The control group will receive a placebo pill and will maintain all eating habits while keeping a recall diary of their dietary behavior. The primary outcome measure will be change in apnea-hypopnea index. The secondary outcome measures will be variations of: anthropometric and bioelectrical impedance variables, office blood pressure, respiratory variables from in-home level III polysomnography, excessive daytime sleepiness, glycolipid profile, C-reactive protein, 24 h urinary variables, and adverse events.

Discussion

Despite the high efficacy of continuous positive airway pressure to reverse upper airway obstruction in sleep apnea, partial adherence to this form of treatment reduces its efficiency. Thus, additional forms of treating apnea need to be investigated. If the results of this proof-of-concept trial show that decreases in bodily fluid content, either by diuretic or dietary intervention, reduces the severity of sleep apnea, further investigation will be necessary before these results can be translated and adopted as an adjunct apnea therapy.

Trial registration

clinicaltrials.gov NCT01945801.

Very early screening for sleep-disordered breathing in acute coronary syndrome in patients without acute heart failure

BACKGROUND

Obstructive sleep apnea (OSA) is frequently associated with acute coronary syndrome (ACS). Screening of sleep-disordered breathing (SDB) has not been previously evaluated in ACS within 72 h in intensive care settings and its management could potentially enhance patients' prognosis. This pilot study assessed the feasibility of SDB screening at the early phase of ACS.

METHODS

All consecutive patients admitted to the coronary care unit (CCU) for ACS without acute heart failure underwent one overnight-attended polysomnography (PSG) within 72 h after admission. A telemonitoring (TM) system was set up to remotely monitor the signals and repair faulty sensors. The 27 recordings were analyzed as respiratory polygraphy (RP) and as PSG, and the results were compared.

RESULTS

The TM system allowed successful intervention in 48% of recordings, resulting in excellent quality PSG for 89% of cases. The prevalence of SDB [apnea-hypopnea index (AHI) ≥ 15/h] was 82% and mainly consisted of central SDB and periodic breathing, except three patients with OSA. Compared with PSG, RP underestimated AHI, probably due to the poor sleep efficiency, reduction of slow-wave sleep, and alteration of rapid eye movement sleep.

CONCLUSION

An early SDB screening by remote-attended PSG is feasible in ACS patients shortly after admission to CCU. The TM enhanced the quality of PSG. A high prevalence of central SDB was noticed, for which the etiology remains unknown. Further large-scale studies are needed to determine whether central SDB is an incidental finding in early ACS and whether the presence and severity of SDB have a prognostic impact.

Sleep apnea and cardiovascular risk

Sleep apnea is evident in approximately 10% of adults in the general population, but in certain cardiovascular diseases, and in particular those characterized by sodium and water retention, its prevalence can exceed 50%. Although sleep apnea is not as yet integrated into formal cardiovascular risk assessment algorithms, there is increasing awareness of its importance in the causation or promotion of hypertension, coronary artery disease, heart failure, atrial arrhythmias, and stroke, and thus, not surprisingly, as a predictor of premature cardiovascular death. Sleep apnea manifests as two principal phenotypes, both characterized by respiratory instability: obstructive (OSA), which arises when sleep-related withdrawal of respiratory drive to the upper airway dilator muscles is superimposed upon a narrow and highly compliant airway predisposed to collapse, and central (CSA), which occurs when the partial pressure of arterial carbon dioxide falls below the apnea threshold, resulting in withdrawal of central drive to respiratory muscles. The present objectives are to: (1) review the epidemiology and patho-physiology of OSA and CSA, with particular emphasis on the role of renal sodium retention in initiating and promoting these processes, and on population studies that reveal the long-term consequences of untreated OSA and CSA; (2) illustrate mechanical, autonomic, chemical, and inflammatory mechanisms by which OSA and CSA can increase cardiovascular risk and event rates by initiating or promoting hypertension, atherosclerosis, coronary artery disease, heart failure, arrhythmias, and stroke; (3) highlight insights from randomized trials in which treating sleep apnea was the specific target of therapy; (4) emphasize the present lack of evidence that treating sleep apnea reduces cardiovascular risk and the current clinical equipoise concerning treatment of asymptomatic patients with sleep apnea; and (5) consider clinical implications and future directions of clinical research and practice.

Increased dietary sodium is related to severity of obstructive sleep apnea in patients with resistant hypertension and hyperaldosteronism

BACKGROUND

Obstructive sleep apnea (OSA) is a strong and independent risk factor for the development of hypertension, particularly resistant hypertension, and cardiovascular diseases. Patients with resistant hypertension have a high prevalence of OSA in association with elevated aldosterone levels, high salt intake, and salt-sensitive BP. The objective of this study was to determine whether dietary salt and aldosterone are associated with severity of OSA in patients with resistant hypertension.

METHODS

Ninety-seven patients with resistant hypertension were prospectively evaluated by overnight polysomnography and 24-h urinary sodium and aldosterone levels while maintaining their usual diet. Hyperaldosteronism was defined as a plasma renin activity of < 1 ng/mL/h and urinary aldosterone level of ≥ 12 μg/24 h.

RESULTS

Overall, patients' mean clinic BP was 156.3 ± 22.4/88.9 ± 13.3 mm Hg while taking an average of 4.3 ± 1.1 antihypertensive medications. Prevalence of OSA was 77.3%. Twenty-eight (28.9%) patients had hyperaldosteronism. Urinary sodium level was an independent predictor of severity of OSA only in patients with hyperaldosteronism.

CONCLUSIONS

The findings suggest that dietary salt is related to the severity of OSA in patients with resistant hypertension and hyperaldosteronism. The results support dietary salt restriction as a treatment strategy for reduction of OSA severity in these patients.

Role of nocturnal rostral fluid shift in the pathogenesis of obstructive and central sleep apnoea

Obstructive sleep apnoea (OSA) is common in the general population and increases the risk of motor vehicle accidents due to hypersomnolence from sleep disruption, and risk of cardiovascular diseases owing to repetitive hypoxia, sympathetic nervous system activation, and systemic inflammation. In contrast, central sleep apnoea (CSA) is rare in the general population. Although their pathogenesis is multifactorial, the prevalence of both OSA and CSA is increased in patients with fluid retaining states, especially heart failure, where they are associated with increased mortality risk. This observation suggests that fluid retention may contribute to the pathogenesis of both OSA and CSA. According to this hypothesis, during the day fluid accumulates in the intravascular and interstitial spaces of the legs due to gravity, and upon lying down at night redistributes rostrally, again owing to gravity. Some of this fluid may accumulate in the neck, increasing tissue pressure and causing the upper airway to narrow, thereby increasing its collapsibility and predisposing to OSA. In heart failure patients, with increased rostral fluid shift, fluid may additionally accumulate in the lungs, provoking hyperventilation and hypocapnia, driving below the apnoea threshold, leading to CSA. This review article will explore mechanisms by which overnight rostral fluid shift, and its prevention, can contribute to the pathogenesis and therapy of sleep apnoea.

Supine fluid redistribution: should we consider this as an important risk factor for obstructive sleep apnea?

INTRODUCTION

Obstructive sleep apnea (OSA) is a common medical disorder affecting at least 2 % of women and 4 % of men living in Western societies. Obesity, older age, male gender, alcohol and sedative use, smoking, craniofacial parameters, and volume overload are some of the risk factors for this disorder.

DISCUSSION

OSA is a known risk factor complicating the course of arterial hypertension, heart failure, and chronic kidney disease. It is important to note that all of the aforementioned comorbid disorders are associated with volume overload. This explains why patients with OSA and comorbid disorders associated with fluid overload can benefit from treatment with diuretics and drugs modulating the renin-angiotensin-aldosterone system. Additionally, patients with heart failure and high sodium intake are at increased risk for OSA, further supporting the complex interrelationship.

CONCLUSIONS

Hemodialysis and renal transplantation can markedly improve the severity of OSA in patients with concomitant kidney disease. Finally, there is a potential of a vicious cycle between OSA and fluid overload disorders, whereby OSA can contribute to the pathogenesis of arterial hypertension, heart failure, and chronic kidney disease, which in turn will significantly contribute to the course OSA.

Sleep apnea and heart failure

Sleep apnea is frequently observed in patients with heart failure (HF). In general, sleep apnea consists of two types: obstructive and central sleep apnea (OSA and CSA, respectively). OSA results from upper airway collapse, whereas CSA arises from reductions in central respiratory drive. In patients with OSA, blood pressure is frequently elevated as a result of sympathetic nervous system overactivation. The generation of exaggerated negative intrathoracic pressure during obstructive apneas further increases left ventricular (LV) afterload, reduces cardiac output, and may promote the progression of HF. Intermittent hypoxia and post-apneic reoxygenation cause vascular endothelial damage and possibly atherosclerosis and consequently coronary artery disease and ischemic cardiomyopathy. CSA is also characterized by apnea, hypoxia, and increased sympathetic nervous activity and, when present in HF, is associated with increased risk of death. In patients with HF, abolition of coexisting OSA by continuous positive airway pressure (CPAP) improves LV function and may contribute to the improvement of long-term outcomes. Although treatment options of CSA vary compared with OSA treatment, CPAP and other types of positive airway ventilation improve LV function and may be a promising adjunctive therapy for HF patients with CSA. Since HF remains one of the major causes of mortality in the industrialized countries, the significance of identifying and managing sleep apnea should be more emphasized to prevent the development or progression of HF.