The prevalence of obstructive sleep apnea increases with progressing renal insufficiency. Recent observations suggest a causative relationship between overnight fluid displacement from the legs to the neck soft tissues and the severity of obstructive sleep apnea. We suspect that this pathophysiologic mechanism could explain the increased prevalence of obstructive sleep apnea in patients with fluid overload, including chronic renal failure.~The beginning of a renal replacement therapy modify the fluid balance of the end stage renal disease patients and could therefore impact on the severity of sleep apnea in this population.~The purpose of this trial is to investigate the hypothesis that the transition from untreated end stage renal disease and a renal replacement therapy decreases the severity of sleep apnea, by a reduction of the fluid overload and of the nocturnal rostral fluid shift.~The severity of obstructive sleep apnea is measured by two attended polysomnographies (PSG), a baseline PSG performed before and a follow-up PSG performed 6 month after beginning of a renal replacement therapy. Overhydration and leg fluid are evaluated by bioimpedance, performed at the beginning and at the end of each polysomnography. Patients who have not yet begun a renal replacement therapy 6 months after the baseline PSG will be re-assessed and will be analyzed as control group
The purpose of this study is to investigate the effect of beginning a renal replacement therapy on fluid overload and its consequence on the severity of obstructive sleep apnea, in patients with end stage chronic kidney disease. It aims further to investigate the relationship between overhydration, nocturnal rostral fluid shift and the severity of sleep apnea.