#5660 ULTRAFILTRATION RATES IN INCIDENT PATIENTS ON INCREMENTAL HAEMODIALYSIS WITH 1 SESSION PER WEEK: ARE THESE RATES DANGEROUS?
Authors: Mayor Elena Jiménez , Rodrigues André Rocha , Aguilar José Carlos Aguilar , Carrero María Elena Davín , Domínguez María Sandra Gallego , Alvarez Jesus Pedro , Santisteban Miguel Angel Suárez , Gomez Pedro Jesus Labrador , Rojas María de Las Mercedes Acosta , Lorenzo Javier Deira 
Published: June 2023

Abstract

Background and Aims
Most patients start haemodialysis (HD) with a fixed dose of three sessions per week, regardless of their residual renal function (RKF). This schedule is considered “standard HD or conventional HD” and is widely accepted without any randomised controlled trial (RCT) having examined whether other schedules with fewer sessions per week are inadequate or harmful. Incremental HD (iHD), by contrast, adjusts the number of sessions to the RKF, increasing the frequency to compensate for the drop in RKF. While iHD approaches precision medicine by customising the number of sessions, it raises concerns about the risk of under-dialysis and long intersession periods. In the absence of RKF, these long periods are associated with high weight gain intersession (WGI), which leads to high ultrafiltration rates (UF rates). UF rates greater than 10 ml/kg/h are known to be associated with poor prognosis [1]. Pending ongoing RCT [2], our aim is to quantify WGI and UF rates in incident patients on iHD with a single weekly session (1HD/Wk).

Method
The policy of our Centre is to start with iHD in those patients with RKF and clinically stable. We start with 1HD/Wk if residual urea clearance (KrU) &gt; 4 ml/min/1.73 m2. We moved from 1 to 2, and from 2 to 3 sessions/week, depending on KrU and ultrafiltration rates. We analysed 2777 HD sessions of 66 incident iHD patients, with intersession period ≥ 6 days. Mean age was 73±12.5 years and 73% were male. WGI, rate UF and Blood Pressure (BP) pre- and post-HD were analysed for each session. We calculated the monthly dialysis dose using Soluter Solver (www.ureakinetic.org). We considered an adequate dose if weekly stdKt/v ≥ 2.1 or if EKRU+KrU ≥ 12 [3]. We guided fluid management by bioimpedance spectroscopy (BIS) bimonthly.

Results
WGI was 1.47±1.3 kg (median 1.4), equivalent to 2±1.5% of patient weight. According to BIS, pre-HD overhydration status was 1.9±1.6 (median 1.6L), similar to WGI. The UF rate, for each session, was 5.03±3.84 ml/kg/h (median 5). 9.1% of the sessions exceeded 10 ml/min/h and 2.6% exceeded 13 ml/kg/h. Pre-dialysis BP was 158±23/78±19 mmHg (median 157/76) and post-dialysis BP was 152±27/76±16 mmHg (median 150/75). RKF measured by urinary volume was 1931±491 ml (median 1900) and KrU was 5,1±1.8 ml/mn/1.73m2 (median 4,8). Dialysis dose was adequate, with a weekly stdK/v of 2,31±0.7 volumes (median 2,23) and EKR+KrU was 14,22±3,7 ml/min (median 13,8). Nutritional status as measured by PCRn was 1,04±0.3 g/kg/day (median 1), LTI index at BIS was 12,1±4,8 kg/m2 (median 12), desirable &gt;10,5, and FTI index was 15±8 kg/m2 (median 14), desirable &gt;7.

Conclusion
Patients on iHD do not present large weight gains, nor are they subjected to high UF rates, avoiding significant changes in their BP during HD sessions. On the contrary, RKF allows them to maintain a low number of weekly sessions without presenting volume overload, underdialysis or malnutrition.