Rostral fluid shifts and other mechanisms of interaction between obstructive sleep apnea and heart failure - a systematic review.

<b>Introduction:</b> Obstructive sleep apnea (OSA) is a chronic inflammatory disorder characterized by episodes of total or partial upper airway obstruction during sleep. Untreated OSA leads to various cardiovascular complications, including heart failure (HF), both involving complex and detrimental pathophysiological processes.<b>Aim:</b> The aim of this study is to describe the role of rostral fluid shifts and other mechanisms responsible for the co-existence of OSA and HF, providing insight into potential diagnostic and therapeutic strategies.<b>Materials and methods:</b> Two authors independently searched the literature and assessed articles following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analytics) guidelines.<b>Results:</b> Rostral fluid shifts, characterized by nocturnal redistribution from the lower limbs to the neck tissues, exacerbate upper airway obstruction by increasing neck circumference and predisposing individuals to respiratory events. This phenomenon is particularly significant in patients with HF due to impaired cardiovascular function leading to fluid retention. The repetitive collapse of the upper airway during sleep triggers abrupt changes in intrathoracic pressure negatively impacting cardiac tissue remodeling by promoting inflammation and fibrosis. Moreover, sleep fragmentation and arousals activate the sympathetic nervous system (SNS), imposing additional strain on the cardiovascular system. Accumulated data suggest that rostral fluid shifts are a clinically significant pathomechanism in the coexistence of OSA and HF. Therapeutic strategies, including the benefits of continuous positive airway pressure (CPAP) therapy and lifestyle modifications, have been discussed. This systematic review highlights the need for integrated treatment approaches to manage both OSA and HF effectively.<b>Conclusions:</b> Understanding and addressing these interconnected mechanisms is essential to offer an integrated diagnostic and therapeutic management of patients, highlighting the importance of multidisciplinary care to optimize patient health and quality of life.