Apnées du sommeil : une question de fluide ?

The prevalence of obstructive sleep apnea (OSA) is higher in patients with fluid-retaining states, such as chronic heart failure (CHF), than in the general population. In patients with CHF, central sleep apnea (CSA), which is rare in the general population, is also common. Although OSA and CSA pathogenesis is multifactorial, these observations suggest that fluid retention may contribute to the development of both types of sleep apnea in CHF and in other fluid retaining states. In particular, excess fluid accumulated in the legs while upright during the day because of gravity, is redistributed rostrally overnight on lying down, again due to gravity. Some of this fluid may reach the neck, increasing tissue pressure around upper airway and thereby predisposing to OSA. In CHF patients, with increased rostral fluid shift, fluid may additionally accumulate in the lungs, provoking hyperventilation, driving PaCO2 below the apnea threshold and thereby triggering CSA. This article will review the evidence supporting overnight rostral fluid shift as a potential contributor to the development of both OSA and CSA.