Fluid Redistribution in Sleep Apnea: Therapeutic Implications in Edematous States

Ketogenic diet acutely improves gas exchange and sleep apnoea in obesity hypoventilation syndrome: A non-randomized crossover study

BACKGROUND AND OBJECTIVE

Obesity hypoventilation syndrome (OHS) causes hypercapnia which is often refractory to current therapies. We examine whether hypercapnia in OHS can be improved by a ketogenic dietary intervention.

METHODS

We conducted a single-arm crossover clinical trial to examine the impact of a ketogenic diet on CO2 levels in patients with OHS. Patients were instructed to adhere to 1 week of regular diet, 2 weeks of ketogenic diet, followed by 1 week of regular diet in an ambulatory setting. Adherence was assessed with capillary ketone levels and continuous glucose monitors. At weekly visits, we measured blood gases, calorimetry, body composition, metabolic profiles, and sleep studies. Outcomes were assessed with linear mixed models.

RESULTS

A total of 20 subjects completed the study. Blood ketones increased from 0.14 ± 0.08 during regular diet to 1.99 ± 1.11 mmol/L (p < 0.001) after 2 weeks of ketogenic diet. Ketogenic diet decreased venous CO2 by 3.0 mm Hg (p = 0.008), bicarbonate by 1.8 mmol/L (p = 0.001), and weight by 3.4 kg (p < 0.001). Sleep apnoea severity and nocturnal oxygen levels significantly improved. Ketogenic diet lowered respiratory quotient, fat mass, body water, glucose, insulin, triglycerides, leptin, and insulin-like growth factor 1. Rebound hypercapnia was observed after resuming regular diet. CO2 lowering was dependent on baseline hypercapnia, and associated with circulating ketone levels and respiratory quotient. The ketogenic diet was well tolerated.

CONCLUSION

This study demonstrates for the first time that a ketogenic diet may be useful for control of hypercapnia and sleep apnoea in patients with obesity hypoventilation syndrome.

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.

Physical activity, sedentary behaviour and incidence of obstructive sleep apnoea in three prospective US cohorts

BACKGROUND

Reduced physical activity and increased sedentary behaviour may independently contribute to the development of obstructive sleep apnoea (OSA) through increased adiposity, inflammation, insulin resistance and body fluid retention. However, epidemiological evidence remains sparse and is primarily limited to cross-sectional studies.

METHODS

We prospectively followed 50 332 women from the Nurses' Health Study (2002-2012), 68 265 women from the Nurses' Health Study II (1995-2013) and 19 320 men from the Health Professionals Follow-up Study (1996-2012). Recreational physical activity (quantified by metabolic equivalent of task (MET)-h per week) and sitting time spent watching TV and at work/away from home were assessed by questionnaires every 2-4 years. Physician-diagnosed OSA was identified by validated self-report. Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals for OSA incidence associated with physical activity and sedentary behaviour.

RESULTS

During 2 004 663 person-years of follow-up, we documented 8733 incident OSA cases. After adjusting for potential confounders, the pooled HR for OSA comparing participants with ≥36.0 versus <6.0 MET-h per week of physical activity was 0.46 (95% CI 0.43-0.50; p_trend<0.001). Compared with participants spending <4.0 h per week sitting watching TV, the multivariable-adjusted HR was 1.78 (95% CI 1.60-1.98) for participants spending ≥28.0 h per week (p_trend<0.001). The comparable HR was 1.49 (95% CI 1.38-1.62) for sitting hours at work/away from home (p_trend<0.001). With additional adjustment for several metabolic factors, including body mass index and waist circumference, the associations with physical activity and sitting hours at work/away from home were attenuated but remained significant (p_trend<0.001), whereas the association with sitting hours watching TV was no longer statistically significant (p_trend=0.18).

CONCLUSIONS

Higher levels of physical activity and fewer sedentary hours were associated with lower OSA incidence. The potential mediating role of metabolic factors in the association between sedentary behaviour and OSA incidence may depend on the type of sedentary behaviour. Our results suggest that promoting an active lifestyle may reduce OSA incidence.

[Chronic obstructive pulmonary disease, sleep-disordered breathing and hypoventilation-Influence on the cardiorenal system]

Comorbidities are frequently observed in patients suffering from pulmonary diseases due to shared risk factors and intricate interactions between various organ systems. This article aims to characterize the effects of selected diseases of the respiratory system on the cardiovascular system and kidneys. Advanced chronic obstructive pulmonary disease (COPD) often leads to a prognostically unfavorable increased pressure in the pulmonary circulation. In this respect treatment of these patients is primarily aimed at the underlying pulmonary disease and targeted treatment of the pulmonary hypertension should only be carried out according to invasive diagnostics and in an individualized manner. So far, the fact that there is a substantial overlap between COPD and heart failure with preserved ejection fraction has been completely ignored, which should be considered in the diagnostic procedure. Obstructive sleep apnea (OSA) has several unfavorable effects on the cardiovascular system and has been identified as an independent risk factor for cardiovascular diseases. The established treatment of OSA with continuous positive airway pressure (CPAP) has been shown to improve daytime sleepiness and the quality of life; however, an effect of CPAP on the occurrence of cardiovascular events, especially in asymptomatic patients, has so far not been demonstrated in randomized trials. Peripheral edema is frequently observed in patients suffering from chronic hypercapnia, which can be explained by several pathophysiological mechanisms, including pulmonary vasoconstriction and a direct effect of the hypercapnia on renal blood flow. Apart from the administration of diuretics, recompensation of such patients always requires treatment of the hypercapnia by noninvasive ventilation.

Artificial intelligence and sleep: Advancing sleep medicine

Artificial intelligence (AI) allows analysis of "big data" combining clinical, environmental and laboratory based objective measures to allow a deeper understanding of sleep and sleep disorders. This development has the potential to transform sleep medicine in coming years to the betterment of patient care and our collective understanding of human sleep. This review addresses the current state of the field starting with a broad definition of the various components and analytic methods deployed in AI. We review examples of AI use in screening, endotyping, diagnosing, and treating sleep disorders and place this in the context of precision/personalized sleep medicine. We explore the opportunities for AI to both facilitate and extend providers' clinical impact and present ethical considerations regarding AI derived prognostic information. We cover early adopting specialties of AI in the clinical realm, such as radiology and pathology, to provide a road map for the challenges sleep medicine is likely to face when deploying this technology. Finally, we discuss pitfalls to ensure clinical AI implementation proceeds in the safest and most effective manner possible.