Morbidity and mortality rates in end stage kidney disease (ESKD) patients remain high. The majority of excess mortality is cardiovascular and infectious in aetiology. Interest has emerged in increasing haemodialysis dose, using more frequent and/or longer duration treatments to improve outcomes. Currently, there is insufficient evidence defining the strengths and weaknesses of different haemodialysis regimens. Alternate daily haemodialysis may offer advantages over daily haemodialysis, including reduced costs, fewer vascular access cannulations and less intrusion on patients’ lifestyles.
Changes in cardiovascular structure, function and risk factors were measured 3-24 months following conversion of 63 prevalent patients from home conventional haemodialysis (CHD: 4-6 hours/session for 3-5 sessions weekly) to alternate nightly home nocturnal haemodialysis (NHD: 6-9 hours/session, 3.5-5 sessions weekly).
Cardiovascular Studies (n=63, Follow up 12-24months): Left ventricular mass index, diastolic function, carotid intima-media thickness, brachial artery reactivity and total arterial compliance remained stable. Augmentation index increased. Blood pressure control improved. Antihypertensive medication use was stable or reduced in the majority. Interdialytic weight gains increased. Lipid profile, haemoglobin and iron stores remained stable. Erythropoietin requirements decreased. There was no appreciable change in oxidative stress parameters over 6 months (n=37).
Bone Mineral Metabolism Studies (n=26, Follow up 12months): Predialysis serum phosphate, calcium-phosphate product and parathyroid hormone levels fell. Use of phosphate binding medication decreased. Bone mineral density remained stable. Vascular and ectopic calcification improved or stabilised. Bone histomorphometry at 12 months showed high, normal and low bone turnover in 10, 3 and 4 patients, respectively, with 35% demonstrating abnormal mineralisation.
Nutritional Studies (n=37, Follow up 6 months): Dry weight and waist / hip circumference remained stable between baseline and 6 months. Fat mass increased whilst lean mass remained stable. Fasting predialysis plasma ghrelin, serum leptin, serum adiponectin and insulin sensitivity remained stable. Serum albumin, C reactive protein, white cell count, vitamins B12 and red cell folate remained stable. Routine water soluble vitamin supplementation, including at least 25mg of pyridoxine was prescribed. Sodium loading was documented in 6/6 patients with high interdialytic weight gains when a 140mmol/L dialysate sodium concentration was used.
Endocrine Function (n=37, Follow up 6 months): In male patients (n=30), serum prolactin fell and total and free testosterone increased. Sex hormone binding globulin, luteinizing hormone and follicle stimulating hormone were unchanged. Regular menses returned in 2/3 premenopausal women. Thyroid function remained stable.
Sleep (n=47, Follow up 3months): Ninety-seven percent had sleep disordered breathing, predominantly moderate to severe obstructive sleep apnoea. There was no significant sleep hypoxia. Fifty-six percent of patients had >15 leg movements/hour. There were no significant changes in sleep architecture, Apnoea/Hypopnoea Index, Arousal Index or Epworth Sleepiness Score. Non-REM sleep mean partial pressure of oxygen improved but other measures of oxygenation did not. The intercept of the carbon dioxide-minute ventilation relationship decreased but the slope was unchanged. Ventilatory response to hypoxia was unchanged. Benzodiazepine use increased.
Quality of Life (n=63, Follow up 6months): Using Kidney Diseases Quality of Life survey, significant improvements in general health and overall health ratings, physical function, physical role and energy and fatigue were observed. The distance covered in the 6 minute walk test improved.
Hospital Admissions and Mortality Rates (n=63): When NHD and button hole cannulation technique were used simultaneously septic dialysis access events were increased compared with 63 patients maintained on facility CHD. Total hospital admissions, hospital admissions for other indications and mortality rates were comparable. The NHD discontinuation rate was one per 3.74 patient-years.
Conclusion: Alternate nightly NHD is a safe and sustainable therapy for ESKD, which can improve bone mineral metabolism, quality of life and fitness when compared to CHD. In contrast to the cardiovascular benefits reported in previous studies of quotidian haemodialysis regimens, no improvements in cardiovascular structure and function or hospitalization rates were observed following conversion to NHD in this study. Moreover, the risk of dialysis access infectious complications appeared to be increased, particularly when the buttonhole cannulation technique was used in conjunction with extended-hours haemodialysis. Care should be taken to ensure a high standard of hygiene is maintained during cannulation and that patients, and staff, are well educated about this risk and can recognise and treat access infection promptly. Consideration should be given to avoiding buttonhole cannulation technique in quotidian haemodialysis patients where possible.
This study highlights important differences in outcomes achieved with various haemodialysis regimens. Interdialytic weight gains remain higher with alternate daily, extended hours, haemodialysis regimens when compared with daily haemodialysis regimens. High interdialytic weight gains may remain a source of ongoing cardiovascular stress and may counteract the effects of improved control of other uraemic toxins.
The study’s conclusions were limited by its observational cohort design. Future randomised controlled trials of the safety, efficacy and cost-effectiveness of augmented dialysis session duration and/or frequency is needed.