S. Redolfi

Targeting volume overload and overnight rostral fluid shift: A new perspective to treat sleep apnea

Sleep apnea is a common condition associated with increased morbidity and mortality. Continuous positive airway pressure and oral appliances are efficient for treating sleep apnea; however, they are often poorly tolerated. Therefore, alternative therapies are needed. Overnight rostral fluid shift has been implicated in the pathogenesis of sleep apnea, particularly in conditions associated with fluid overload. Fluid shift predisposes to both obstructive and central sleep apnea, with the type of sleep apnea being related to whether the fluid shifts from the legs into the neck or chest, respectively. The amount of fluid that shifts from the legs to the upper part of the body at night is correlated with the severity of sleep apnea. As a result of this observation, it has been suggested that the prevention of overnight fluid shift may reduce sleep apnea severity. It has recently been shown that interventions targeting fluid overload and daytime fluid accumulation in the legs consistently attenuate nocturnal fluid shift and sleep apnea, as greater reductions in fluid shift are correlated with greater reductions in sleep apnea severity. This review will focus on interventions that counteract fluid shift, such as diuretics, ultrafiltration/dialysis, physical activity, compression stockings and salt/fluid restriction, which have been shown to have efficacy in reducing sleep apnea severity.

Prevalence and Phenotype of Sleep Disorders in 60 Adults With Prader–Willi Syndrome

Study Objectives Excessive sleepiness is a common symptom in Prader-Willi syndrome (PWS), and it negatively impacts the quality of life. Obstructive sleep apnea and narcolepsy phenotypes have been reported in PWS. We characterized sleep disorders in a large cohort of adults with PWS. Methods All consecutive patients with genetically confirmed PWS unselected for sleep-related symptoms, underwent a clinical interview, polysomnography, and multiple sleep latency tests (MSLT, n = 60), followed by long-term (24 hours) polysomnography (n = 22/60). Results Among 60 adults evaluated (57% female, aged 25 ± 10 years, body mass index: 39 ± 12 kg/m2), 67% reported excessive sleepiness. According to the sleep study results, 43% had a previously unrecognized hypersomnia disorder, 15% had an isolated sleep breathing disorder, 12% had combined hypersomnia disorder and untreated breathing sleep disorder, and only 30% had normal sleep. Isolated hypersomnia disorder included narcolepsy in 35% (type 1, n = 1, and type 2, n = 8), hypersomnia in 12% (total sleep time >11 hours, n = 2, and MSLT <8 minutes, n = 1), and borderline phenotype in 53% (≥2 sleep onset in REM periods and MSLT >8 minutes, n = 10, and 8 minutes < MSLT < 10 minutes, n = 4). Sleep breathing disorders, isolated and combined, included obstructive sleep apnea (n = 14, already treated in seven), sleep hypoxemia (n = 1) and previously undiagnosed hypoventilation (n = 5). Modafinil was taken by 16 patients (well tolerated in 10), resulting in improved sleepiness over a mean 5-year follow-up period. Conclusion Sleepiness affects more than half of adult patients with PWS, with a variety of hypersomnia disorder (narcolepsy, hypersomnia, and borderline phenotypes) and breathing sleep disorders. Earlier diagnosis and management of sleep disorders may improve sleepiness, cognition, and behavior in these patients.