Relationship between salt intake and sleep disordered breathing in dialysis patients

Background The prevalence of sleep disordered breathing is high in patients with end-stage renal disease. Salt intake is related to the severity of obstructive sleep apnea in patients with resistant hypertension and hyperaldosteronism. We investigated the relationship between salt intake and sleep disordered breathing in patients on maintenance hemodialysis. Patients and methods We studied 128 dialysis outpatients (mean age 63 +/- 11 years) who were followed at Kokura Daiichi Hospital. We estimated each patient's salt intake using an InBody S10 body composition analyzer and measured the 3% oxygen desaturation index (ODI) during sleep using a Pulsewatch: PMP-200 GplusX. Results The average estimated salt intake was 8.0 +/- 2.6 g/day, and the median value of that was 7.5 g/day. Blood pressure (BP) before and after dialysis were 140 +/- 18/78 +/- 11 and 127 +/- 13/72 +/- 8 mmHg, respectively. The geometric average number of 3% ODI was 7.1, and sleep disordered breathing was detected in 30% of all subjects. The patients with >= 7.5 g/day salt intake were younger and more frequently male and had higher body mass index (BMI) and BP before dialysis compared to those with salt intakes < 7.5 g/day. Patients with >= 7.5 g/day salt intake had a significantly higher geometric average number of 3% ODI; however, this relationship became weaker after adjusting for BMI. The same relationship was obtained for the prevalence of sleep disordered breathing. Conclusion The prevalence of sleep disordered breathing in patients on maintenance hemodialysis was high, and the sleep disordered breathing was associated with salt intake and BMI.