LAUSR

The most common causes of early primary failures of a vascular access (VA) is related to small caliber vessels. Weight gain between dialyses expands both extracellular and blood volume, which may lead to rises in intravascular filling and vessels caliber. If patients presented after weekend, their weight and probably volemia would be higher. Dry weight concept has evolved over time and nowadays incorporates objective measures of volume status like body bioimpedance spectroscopy (BIA) and lung ultrasound. We hypothesized that preoperative volume status may influence vascular filling and vessels diameter with a significant impact on VA outcomes. A clinical, prospective, randomized, open-label, single-center crossover trial. Inclusion criteria: age 18-80ys, under regular hemodialysis (3/week), no heart failure (CHF) and no acute pulmonar edema (APE) on the previous year. Exclusion criteria: >3 sessions/week, CHF or APE. Before the last-week session, patient’s clinical parameters were recorded. BIA and ultrasound vascular mapping were performed. After this first evaluation, dry weight was increased 0,5 Kg, and after weekend, the same protocol was conducted. Primary end point was to compare vein diameters. 126 vessels were evaluated (84 veins and 42 arteries) from 21 patients. Mean age was 69±10y and 52% female. Primary end point was achieved (Table 1). Other than humeral arterial blood flow, every parameters evaluated through ultrasound mapping significantly increased (p<0,05) after dry weight adjustment (>0,5 Kg) plus weekend weight gain. After cross over, weight, overhydration (OH), extracellular water (ECW) and OH/ECW significantly increased (p<0,05), however, most patients had a mild-moderate OH (86-90%). Blood pressure and total body water haven’t changed significantly. No complications were reported. Some additional degree of OH comparing to midweek weight gain may be effective and safe in improving peripheral vascular conditions that are predictors of VA success. The currently lack of evidence of vascular mapping may be due to the lack of evaluation of cofactors such as volemia. Therefore, BIA and lung ultrasound may be future tools that combined to vascular ultrasound could be a safe and effective way to optimize and evaluate preoperative conditions to improve VA outcomes. Larger and multicentric studies are needed.