A Cross-sectional, Randomised-controlled Study to Investigate the Effect of HDF vs HD in Sleep Apnoea

Sleep Problem in Dialysis Patients Sleep apnoea is a significant issue in patients with end stage kidney disease. Evidence suggests that up to 80% of dialysis patients have sleep apnoea [1], yet the standard haemodialysis treatment does not improve the symptoms of sleep disturbance in most patients [2].

Sleep disturbance is specifically associated with poor quality of life (QoL) [4]; decreased mental and physical function, and adversely impact survival [5-7]. Recent data also suggest that the low oxygen state resulting from sleep apnoea can exaggerate the deterioration of kidney function and increase risk of high blood pressure, cardiovascular abnormality and overall death rates [8]. Despite the significance of sleep apnoea, it is acknowledged that there is insufficient evidence for clinicians to manage this common symptom burden in the dialysis population [9]; and patients who receive maintenance dialysis today still experience poor QoL and worse survival rates compared with most common cancer sufferers [10].

Knowledge Gap It is believed that the mechanism of sleep apnoea in dialysis patients are related to overactive chemoreceptors, which cause destabilisation of the respiratory drive and periodic breathing during the night [13]. Since the chemoreceptors can be triggered by inflammatory blood toxins, which accumulate in kidney failure [14], it is proposed that better clearance of these molecules can improve symptoms and outcomes of sleep apnoea. These molecules are poorly removed by standard haemodialysis [15] and are thought to cause the symptomatic effects of poor kidney function and inflammation, which are associated with poor sleep quality [16].

Better dialysis treatment may play an important role in the management of sleep apnoea. Previous studies have suggested that sleep apnoea may be improved by nocturnal dialysis; an intensive treatment which patients undergo at home, during sleep, for 8-10 hours every night. It provides better blood purification, compared with standard haemodialysis treatment. However, nocturnal dialysis is a home therapy which is not viable for the majority of haemodialysis patients who require care in a clinical setting. There is clearly a need to explore the effectiveness of dialysis treatment on sleep apnoea using a different dialysis model.

Modern dialysis technology, such as Haemodiafiltration (HDF), allows for better removal of toxic molecules such as beta 2 microglobulin (B2M) and C-Reactive protein (CRP), than standard haemodialysis treatment, and may offer the benefits of nocturnal dialysis to all dialysis patients. No one has examined the effect of HDF on sleep apnoea in haemodialysis patients, and the investigators will answer this question in this study.