There is no easily applicable method to determine extra cellular volume and consequently estimate DW. Thus DW has to be clinically defined by ''trial and error'' and several indirect methods.

Recently, devices to measure DW by Bioimpedance spectroscopy (BİS) have become available. This non-invasive, cheap easily repeatable method has the potential to improve dialysis outcome in the majority of patients all over the world, The aim of the present project is to assess the feasibility of volume control by using a BİS device.

The excessive mortality of dialysis patients, particularly from cardiovascular events, is undoubtedly related for a large part to hypertension and cardiac damage(1). Most studies reveal that hypertension persists despite antihypertensive drugs. Some authors (Parfrey) have used the term ''natural history'' of heart disease in dialysis, suggesting that deterioration is inevitably linked to that procedure (2).

In sharp contrast, other studies (Charra, Özkahya)(3,4) have shown that a strict volume control strategy decreases blood pressure (BP) without drugs, and prolongs survival. This suggests that volume control is insufficient in most dialysis centers, despite the fact that treating physicians may consider that ''Dry Weight'' (DW) of their patients has been reached. In fact, there is no easily applicable method to determine extra cellular volume and consequently estimate DW. Thus DW has to be clinically defined by ''trial and error'' and several indirect methods.

Recently, devices to measure DW by Bioimpedance spectroscopy (BİS) have become available. This non-invasive, cheap easily repeatable method has the potential to improve dialysis outcome in the majority of patients all over the world, The aim of the present project is to assess the feasibility of volume control by using a BİS device and compare the results with the conventional ways of treatment.

Conventional ways to estimate DW (5)Intradialytic hypotension continues to be a leading problem, especially in the elderly and cardiovascularly compromised patient. This predominance can be explained by the fact that structural and functional abnormalities of the heart and blood vessels increase the sensitivity of the patient to changes in fluid status. It does not only cause discomfort, but also increases mortality. In a recent study, a low post-dialytic blood pressure was associated with a significantly increased risk for mortality . Therefore prevention of intradialytic hypotension, remains an important challenge to the dialysis physician.

The occurrence of hypotension during ultrafiltration (UF) necessitates termination of the UF procedure and is commonly considered as a sign that DW has been reached. However, although intradialytic hypotension is commonly considered to be a sign of hypovolemia, this is not always correct, because too rapid removal of large amounts of fluid within a few hours causes a temporary state of disequilibrium. It has been shown that achievement of DW by volume control in fact decreases the number of hypotensive episodes (5) Therefore, there is a need for objective methods to estimate the body fluid volumesThis prospective, randomized, controlled study aims to evaluate the usefulness of the new BCM device as a method to improve volume control dialysis patients and compare the results with those obtained by conventional volume control modalities. To our knowledge such an investigation has not been done elsewhere.

The investigators believe that the proposed study will produce powerful evidence to convince the nephrological society of the need for strict volume control strategy by using new device BCM in hemodialysis patients. The expected data may change routine practice causing achievement of normal blood pressure level without using anti-hypertensive medication.

Inclusion Criteria:

• Age older than 18-year,
• Maintenance bicarbonate HD scheduled thrice weekly (12 hours/week),
• Willingness to participate in the study with a written informed consent.

Exclusion Criteria:

• Presence of a cardiac stent, pacemaker or defibrillator ,
• Artificial joints, pin or amputation
• Permanent or temporary catheters (may affect BCM measurement),
• Beeing scheduled for living donor renal transplantation,
• Presence of serious life-limiting co-morbid situations, like malignancy, uncontrollable infection, end-stage cardiac, pulmonary, or hepatic disease,
• Pregnancy or lactating,
• Current use of investigational drugs or participation in an interventional clinical trial that contradicts or interferes with the therapies or measured outcomes in this trial,
• Mental incompetence.