Probing the Dry Weight by Bioimpedance: The Resistance Stabilization Test

Probing the Dry Weight (DW) by Bioimpedance (BIA): Which is the Gold Standard Between Clinical DW and BIA DW?

Clinical methods are fundamental in probing the DW. They must be supported by strict BIA protocols. REST appears to be a (the) brilliant solution in solving the old problem of DW in HD patients

Probing the dry weight (DW) was largely dependent on clinical subjective estimates until recently. New bedside non-invasive tools have been developed with the aim of providing more objective information on volume status and guiding physicians in the quest for DW. Among them, bioimpedance (BIA) appears to be very promising. Very recently, a BIA test aimed at assessing DW in hemodialysis (HD) patients has been developed, the "REsistance Stabilization Test" (REST). It is called BIA DW. Its rationale is based on the achievement of the flattening of the curve of the ratio R0/Rt (R0 is resistance at time 0 and Rt is resistance at a given time t during the HD session) of less than + 1% over 20 minutes in the presence of ongoing ultrafiltration. Study protocol: the Clinical DW is the gold standard by definition. It is determined under strict clinical surveillance by the same attending physician. She/he will be helped by a clinical score of volume state about symptoms and signs of hypo- or hypervolemia. Then, this Clinical DW will be compared with BIA DW, as obtained after performing REST

All patients undergo a Clinical DW assessment. Then, they undergo a HD session in which BIA DW (injection of 800 microAmpere at 50 kilohertz alternating sinusoidal current with a standard tetrapolar technique) is determined. BIA DW is determined by performing the REsistance Stabilization Test (REST).

Assessment of the gold standard method for the measurement of DW (in kg) through the comparison of clinical DW (as determined by means of a validated clinical score) and BIA DW (measurement of the resistance in kilohertz).

Inclusion Criteria stable uremic patients thrice weekly hemodialysis treatment start of hemodialysis treatment since at least 3 months Exclusion Criteria overt edema liver cirrhosis cardiac failure serum albumin < 3g/dl pregnancy metallic implants or a pacemaker limb amputation

Basile C, Libutti P, Lisi P, Rossi L, Lomonte C. Probing the dry weight by bioimpedance: the resistance stabilization test. J Nephrol. 2015 Aug;28(4):517-20. doi: 10.1007/s40620-014-0159-8. Epub 2014 Dec 6.