Frequent haemodialysis

Haemodialysis is a renal replacement treatment, an ‘artificial kidney’ that performs some of the functions of the normal kidney. It is an inelegant device, providing only a fraction of native kidney’s ability to filter toxins from the blood, but with none of the responsiveness to volume, fine feedback control to regulate solute concentrations, or endocrine functions of the healthy organ. Conventional haemodialysis performed three times a week for 4 hours per treatment filters the blood for only 12 of 168 hours each week, and removes less than 10 per cent of small solutes like urea than does the normal kidney. It is therefore not surprising that haemodialysis patients suffer high morbidity and mortality. A dialysis patient’s expected remaining lifetime is substantially shorter than a comparable person with normal kidney function. For example, a woman aged 40–44 years old in the general population can expect on average 40 more years of life, but if she is on dialysis her life expectancy is only 8.1 years. She is also more likely to have co-morbid disease, including hypertension, cardiovascular disease, metabolic bone disease, anaemia, sepsis, depression, malnutrition and inflammation, and physical and cognitive impairment.