**11. Conclusions**

The growing number of patients with CKD/KDOQI stage 5D is characterised by higher age and increasing comorbidities such as arterial hypertension, diabetes mellitus, arteriosclerosis and atherosclerosis, coronary heart disease as well as peripheral arterial perfusion impairments. In the large majority of patients, age and morbidity-related vascular alterations result in a reduced refilling capacity from the extracellular and intracellular compartment into the intravasal compartment.

The divergence between ultrafiltration and absent refilling can lead to severe hypotensive events during the course of the dialysis. Incidence and intensity of hypotensive complications are correlated with morbidity, frequency of hospitalisation, myocardial and cerebral ischemia and consecutively with mortality.

The complications are preventable by increasing the dialysis time and frequency, decreasing the dialysate temperature, increasing the dialysate calcium concentration and/or with online hemodiafiltration. Nonetheless, dialysis time and frequency are finite, and affects the staff and unit workload, while elevated dialysate calcium concentrations could lead to positive mass balance with cumulative calcium overload exposing the patients to higher risk of valvolar and vascular calcification. Nevertheless, hemodiafiltration, due to the high efficiency and high solute extraction, can yield to transient electrolyte and osmolar disequilibrium (Ursino et al, 1997) opposing to plasma refilling and exposing to higher risk of electrical disequilibrium and cardiac dysrhythmias especially in fragile patients, Then, HBS lends itself as a gentle and effective procedure to improve the refilling capacity, to prevent hypotensive events and to optimize the post-dialysis weight. Under HBS, arterial hypertension was improved, dialysis therapy more effective, the body weight optimised, the myocardial function improved, the risk of intradialytic hypotension lower and the patients' quality of life during intradialytic and interdialytic intervals improved.

HBS is a treatment option for elderly, morbid dialysis patients.
