[Comparison of methodologies to reach 'dry weight']

In clinical practice it is very difficult to determine a final weight that is the expression of normovolemia. In hemodialysis (HD), 'dry weight' is conventionally defined as the weight reached by the patient at the end of that hemodialytic session when the maximum quantity of fluids is removed without inducing any symptomatology. The determination of dry weight has been based on the application of clinical criteria. The use of artificial kidneys with blood volume (BV) sensors has allowed the determination of dry weight through the interpretation of changes in the intradialytic BV curve. Conventional bioimpedance analysis (BIA), or better, the vectorial BIA (BIVA) is a new method for determining dry weight. This study evaluated the use of the above-mentioned method for the proper governing of dry weight.

Twenty HD patients were observed for 4 weeks. In the 1st week, the clinical symptomatology of every patient was monitored during both HD sessions and interdialytic periods. During the 2nd week, intradialytic changes in the BV of each patient were observed on artificial kidneys. In the 3rd week, a cardiologist monitored patients before and after hemodialytic treatments. In the 4th week, the body composition of each patient was analyzed through bioelectrical bioimpedance.

Patients, who had clinically shown symptoms of hyperhydration, to the contrary at BIA were dehydrated. Conversely, patients who had dehydration symptoms presented signs of hyperhydration at BIA.

BIVA is the diagnostic instrument that more accurately demonstrates the hydration state of hemodialytic patients. It contributes in defining dry weight more efficiently.