Rationale and objectives

1. Patients on On Line Hemodiafiltration (OL- HDF) are more stable hemodynamically with less Intra Dialytic Hypotension (IDH) episodes compared to conventional hemodialysis (HD). The investigator will follow the hemodynamic parameters during the dialysis sessions (HD and OL-HDF) by using the new non invasive technology, the NICAS device.
2. By switching each patient with IDH from HD to OL- HDF, the investigators will evaluate the hemodynamic parameters and compare the two renal replacement treatment modalities, and prove the superiority of OL-HDF over HD regarding the hemodynamic measures.

Intradialytic hypotension (IDH) or a significant fall in blood pressure (BP) is the most common complication that occurs during hemodialysis (HD) treatment, occurring in up to 20-33% of sessions.

Different mechanisms are involved in the pathogenesis of IDH including acute central hypovolemia, may be precipitated by rapid or excessive ultrafiltration that lead to intravascular volume depletion beyond the level of hemodynamic compensatory response. Other proposed mechanisms of intra vascular depletion are volume shift into the extra-vascular space due to rapid reduction in plasma osmolality, slow and incompatible vascular refilling rate and incorrectly low prescribed dry weight.

Autonomic dysfunction occurs in considerable amount of dialysis patients up to about 50% . This dysfunction reduces the ability to produce an adequate sympathetic response in the setting of acute volume diminution.

Due to the complexity of the dialysis treatment and absence of non- invasive technology, few studies followed the hemodynamic changes which occur during a dialysis session especially during IDH episodes.

OL- HDF is a relatively new method of therapy that allows a larger volume of blood filtration during a single dialysis therapy compared with standard hemodialysis.

Compared to conventional HD treatment, OL-HDF treatment was associated with lower incidence of IDH and better hemodynamic stability.

Bioelectrical impedance analysis is a method for estimating body composition in most of the cases. The Non-Invasive Cardiac System (NICaS) device (non-invasive cardiac system) applies the principle of Whole Body Bio-Impedance and provides continuous data regarding the hemodynamic status (i.e. heart rate, stroke volume, cardiac output, cardiac index, and total peripheral vascular resistance) as well as respiration rate and total body water.

Following the hemodynamic changes, the NICaS device will allow to shed light on the physiological mechanisms underlying the IDH phenomenon and prove the superiority of OL-HDF over regular hemodialysis regarding the hemodynamic measures.

Inclusion Criteria:

• Patients affected by IDH during one or more dialytic sessions every week

Exclusion Criteria:

• Patients with recent change in chronic medications, chronic liver disease, recent acute coronary event, cardiac arrhythmias and acute infection.