Reduced Cardiovascular Morbidity in Obesity-Hypoventilation Syndrome: An Ischemic Preconditioning Protective Effect?

My voyage in the enchanted world of sleep

In this paper, I describe my 45-year career in sleep research. I started my undergraduate studies at Tel Aviv University, where I was first introduced to the enchanted world of sleep, continued to my graduate studies with Wilse B. Webb at the University of Florida, and then to post-doctoral training with Dan Kripke at the University of California at San Diego. Then, I describe the evolution of my academic career at the Technion-Israel Institute of Technology, where I started in 1975 as an Assistant Professor and retired in 2019 as the President of the Institute. I describe the areas of research that I pursued and how the research developed, emphasizing unexpected results that guided me and my lab team in new directions. This includes my early studies on ultradian rhythms, inspired by Nathaniel Kleitman's Basic Rest Activity Cyle hypothesis, utilizing the ultrashort sleep-wake paradigm to chart the 24-hour sleep propensity function, and how these studies led us to explore the role of melatonin in sleep regulation. I also explain why we directed our attention to sleep apnea, and how clinical observations led to the provocative hypothesis that sleep apnea-typically seen as a disorder-may also play a protective role. Under the leadership of my research partner and wife, Lena, we confirmed this hypothesis. Also in this article, I describe my enthusiasm for the history of our field and, as derived from my experience as a Dean of Medicine and President of a university, I share my philosophy about the role of members of academia in society. I emphasize that none of my achievements could have been accomplished without the hard work and motivation of my students and research partners, who shared my enthusiasm and passion for the enchanted world of sleep. This paper is part of the Living Legends in Sleep Research series, which is sponsored by Idorsia Pharmaceuticals and Jazz Pharmaceuticals.

Snoring Survivors: the impact of obstructive sleep apnoea and continuous positive airway pressure use on in-hospital mortality, length of stay and costs among patients hospitalised with acute cardiovascular disease - A retrospective analysis of 2016-2019 National Inpatient Sample Data

BACKGROUND

The routine administration of supplemental oxygen to non-hypoxic patients with acute myocardial infarction (AMI) has been abandoned for lack of mortality benefit. However, the benefits of continuous positive airway pressure (CPAP) use in patients hospitalised with acute cardiovascular disease and concomitant obstructive sleep apnoea (OSA) remain to be elucidated.

METHODS

In this retrospective case-control analysis, using 10th International Classification of Diseases, Clinical Modification (ICD-10) codes, we searched the 2016-2019 Nationwide Inpatient Sample for patients diagnosed with unstable angina (UA), AMI, acute decompensated heart failure (ADHF) and atrial fibrillation with rapid ventricular response (AFRVR), who also carried a diagnosis of OSA. We identified in-hospital CPAP use with ICD-10-Procedure Coding System codes. In-hospital death, length of stay (LOS) and hospital charges were compared between patients with and without OSA, and between OSA patients with and without CPAP use.

RESULTS

Our sample included 2 959 991 patients, of which 1.5% were diagnosed with UA, 30.3% with AMI, 37.5% with ADHF and 45.8% with AFRVR. OSA was present in 12.3%. Patients with OSA were more likely to be younger, male, smokers, obese and have chronic obstructive pulmonary disease, renal failure and heart failure (p<0.001 for all). Patients with OSA had significantly lower in-hospital mortality (aOR 0.71, 95% CI (0.7 to 0.73)). Among patients with OSA, CPAP use significantly increased the odds of in-hospital death (aOR 1.51, 95% CI (1.44 to 1.60)), LOS (adjusted mean difference of 1.49 days, 95% CI (1.43 to 1.55)) and hospital charges (adjusted mean difference of US$1168, 95% CI (273 to 2062)).

CONCLUSION

Our study showed that patients with recognised OSA hospitalised for AMI, ADHF and AFRVR had significantly lower mortality regardless of CPAP use, while CPAP treatment among these patients was associated with significantly higher in-hospital mortality and resource utilisation. The routine use of CPAP during acute cardiovascular encounters could neutralise the impact of chronic intermittent ischaemic preconditioning.

Cardiovascular disease in obesity hypoventilation syndrome - A review of potential mechanisms and effects of therapy

Cardiovascular disease is common in patients with obesity hypoventilation syndrome (OHS) and accounts in part for their poor prognosis. This narrative review article examines the epidemiology of cardiovascular disease in obesity hypoventilation syndrome, explores possible contributing factors and the effects of therapy. All studies that included cardiovascular outcomes and biomarkers were included. Overall, there is a higher burden of cardiovascular disease and cardiovascular risk factors among patients with obesity hypoventilation syndrome. In addition to obesity and sleep-disordered breathing, there are several other pathophysiological mechanisms that contribute to higher cardiovascular morbidity and mortality in OHS. There is evidence emerging that positive airway pressure therapy and weight loss have beneficial effects on the cardiovascular system in obesity hypoventilation syndrome patients, but further research is needed to clarify whether this translates to clinically important outcomes.

Obstructive Sleep Apnea Phenotypes and Markers of Vascular Disease: A Review

Obstructive sleep apnea (OSA) is a chronic and heterogeneous disorder that leads to early mortality, stroke, and cardiovascular disease (CVD). OSA is defined by the apnea–hypopnea index, which is an index of OSA severity that combines apneas (pauses in breathing) and hypopneas (partial obstructions in breathing) associated with hypoxemia. Yet, other sleep metrics (i.e., oxygen nadir, arousal frequency), along with clinical symptoms and molecular markers could be better predictors of stroke and CVD outcomes in OSA. The recent focus on personalized medical care introduces the possibility of a unique approach to the treatment of OSA based on its phenotypes, defined by pathophysiological mechanisms and/or clinical presentation. We summarized what is known about OSA and its phenotypes, and review the literature on factors or intermediate markers that could increase stroke risk and CVD in patients with OSA. The OSA phenotypes where divided across three different domains (1) clinical symptoms (i.e., daytime sleepiness), (2) genetic/molecular markers, and (3) experimental data-driven approach (e.g., cluster analysis). Finally, we further highlight gaps in the literature framing a research agenda.