Obstructive sleep disordered breathing is more prevalent in end stage kidney disease patients than in the general population, and may participate to the increased cardiovascular mortality observed in this group of patients. Despite a significant increase in knowledge about the harmful effects of obstructive sleep apnea, the pathophysiological mechanisms are poorly understood. Recent observations suggest a causative relationship between overnight fluid displacement from the legs to the neck soft and the severity of obstructive sleep apnea. This mechanism was demonstrated in otherwise healthy subjects, in heart failure patients, and in patients with venous insufficiency. We thus suspect that this pathophysiologic mechanism could explain the increased prevalence of obstructive sleep apnea in patients with hypervolemia, including chronic renal failure.~The purpose of this trial is to investigate the hypothesis that nocturnal rostral fluid ship is linked to overhydration and participates significantly to the severity of obstructive sleep apnea in patients on hemodialysis. The correction of overhydration by hemodialysis should therefore reduce the amount of nocturnally displaced water and consequently lower the severity of obstructive sleep apnea.~The severity of obstructive sleep apnea is measured by two consecutive attended polysomnographies, performed before and after an ambulatory hemodialysis session with fluid removal, whereas overhydration and leg fluid are evaluated by bioimpedance, performed at the beginning and at the end of each polysomnography. The sequence of the two polysomnographies with respect to hemodialysis is randomized, to minimize the first-night effect.
The purpose of this study is to investigate the effect of decreasing fluid overload by hemodialysis on the severity of obstructive sleep apnea, in patients with end stage chronic kidney disease on intermittent hemodialysis. It aims further to investigate the relationship between overhydration, nocturnal rostral fluid shift and the severity of sleep apnea.