Randomized Study Comparing Analysis With Bioeletric Impedance and Clinical Evaluation to Determine Dry Weight in Hemodialyis Patients

Adequate control of extracellular volume is a major goal of renal replacement therapy in patients with chronic renal disease. Fluid overload is present in the early stages of chronic kidney disease and contributes significantly to hypertension, arteriosclerosis and high prevalence of left ventricular hypertrophy. These are associated with high rates of morbidity and mortality in this group of patients, rates on dialysis in Brazil is around17.9 % per year. Dry weight during hemodialysis remains a delicate gap between hypervolemia and hypovolemic. Many studies have shown that tight control of post - dialysis weight is related to better outcomes in short term and higher long-term survival. Many methods have been proposed for estimating the hydration status of hemodialysis patients in an objective manner, including ultrasonography of the inferior vena cava and echocardiography. However, these methods are very time-consuming and cumbersome to use in daily practice. In most dialysis centers, the dry weight is evaluated on subjective clinical criteria, with trial and error and time consuming. It was recently introduced in Brazil to monitor body composition by multifrequency bioimpedance, called Body Composition Monitor ( BCM ) manufactured by Fresenius Medical Care. The BCM is a piece of bioimpedance spectrometry using a three compartment model, able to quantify objectively and accurately the extracellular volume and hydration status of each patient by measuring body resistance to an electric current. The procedure is safe, simple and relatively inexpensive. The BCM uses multi-frequency currents (ranging from 5 to 1000 KHz ). The availability of this device evaluation of body composition which assesses the dry weight more efficiently and objectively determine a target to be achieved to prevent left ventricular hypertrophy, hypertension better manage and improve cardiovascular outcomes, motivates us to perform this study. So the goal is to compare the efficacy between bioelectrical impedance analysis and clinical evaluation for suitability of dry weight in hemodialysis patients. A prospective, randomized, crossover study, which will include all chronic renal failure patients on hemodialysis at St. Luke 's Hospital (PUC - RS), including patients with at least three months on HD and over 18 years of age. The expected primary outcome is to achieve greater accuracy in determining the state of hydration and dry weight of these patients.