Body Composition Monitor Among Daily Home Dialysis With Low Flow Dialysate

Study objectives

This study is a cross sectional, observational trial in 11 centers in France. The primary objective is to analyze hydration status in a representative sample of prevalent Daily Home Dialysis with low-flow Dialysate patients.

Secondary objectives are to identify associations between hydration status and patient characteristics and treatment practice in order to find out which conditions should alert the clinician to potential fluid overload, to compare these results with the peritoneal dialysis population and in center hemodialysis population, to evaluate the correlation between impedancemetry and blood pressure in this population, to assess the nutritional status and evaluation of a new method of measurement of kt / V based on impedancemetry, without recourse to a blood test.

Centers

Participants in this study are: CHU de Caen, Tenon Hospital, CHG Saint-Lô, CHG Alençon, CHG Flers, CHG Lisieux, CHG Evreux, ANIDER Rouen, CHG Le Havre, A.U.B Rennes, A.D.P.C Marseille.

Patients

In each center, all prevalent patients, for more than 3 months, on Daily Home Dialysis with Low-flow Dialysate are assessed for eligibility for inclusion if they are older than 18 years of age and want to sign informed consent. Patients are excluded if they have a cardiac pacemaker or metallic implants, are amputees or are pregnant. Patients are evaluated during a routine clinical visit. All patients will signed informed consent, and ethical advice is obtained.

Measurements of hydration and body composition

BCM measurements will be performed in each center by one reference physician or nurse, using a portable whole body bioimpedance spectroscopy device, the BCM (Fresenius Medical Care). The BCM measures the impedance spectroscopy at 50 different frequencies between 5 kHz and 1 MHz. The BCM was validated intensively against all available gold-standard methods.

The measurement will be performed in pre-dialysis, electrodes will be attached to one hand and one foot at the ipsilateral side, after the patient will be in recumbent position for at least 5 minutes. Reproducibility of BCM derived parameters is high, with a coefficient of variation for the interobserver variability ECW and TBW around 1.2%. Therefore, only one BCM measurement is performed in each individual patient.

Extracellular water (ECW), intracellular water (ICW) and total body water (TBW) are determined from the measured impedance data following the model of Moissl et al en 2006.

Fluid overload is expressed by a compartment called OH (overhydration). OH represents the difference between the amount of ECW in the tissue as actually detected by the BCM and the amount of water present in tissue, as predicted by physiological models under normal physiological (normohydrated) conditions. Of note, OH has no direct relation to circulating volume.

Four hydrations groups are defined, based on studies by Wieskotten et al. on healthy population and Wabel et al. on a dialysis population: Normohydrate group: OH between -1.1L and + 1.1L (corresponding to the 10th and 90th percentiles of a population of the same gender distribution and with a comparable age band out of a healthy reference cohort, where hydration status was measured with the identical technology); Hypovolemic group: OH <-1.1L; Fluid overload group: OH between + 1.1L and + 2.5L; Severe fluid overload group: OH> + 2.5L.

The post-dialysis OH status will be obtained by the difference between pre-dialysis OH obtained by impedancemetry and the UF performed.

Blood pressure will be performed in pre-dialytic and post-dialytic and is recorded as the mean of two consecutive measurements with 5 minutes interval, using one single calibrated device in each center. The investigator defined 3 groups according to pre-dialysis systolic blood pressure (SBP): Hypertensive: SBP > 140 mmHg; Normotendu: SBP [100-140 mmHg]; Hypotensive: SBP < 100 mmHg.

Height and weight will be measured using one single calibrated device in each center.

Clinically relevant parameters will be registered in the case report form (CRF).

Nutritional assessment

Nutritional status is evaluated using three methods:

The first one is The Mini Nutritional Assessment (MNA), on 30 points, is a questionnaire of 18 questions to define three groups: 24-30 points: normal nutritional status; 17-23.5 points: risk of malnutrition and < 17 points: poor nutritional status.

The second one is the Scale of Assessment of the food intake (EPA) is a rapid tool based on self-assessment by analog scale from 0 to 10. An EPA> 7 should result in nutritional management.

The third is according to the impedancemetry. The BCM (Fresenius Medical Care), provides, according to Chamney et al. Model, two parameters: "LTM" and "FTM" for "lean tissue mass" and "fat tissue mass". The values obtained will be normalized to the body surface, to allow a comparison between patients of different size, thus giving the lean tissue index (LTI = LTM / height2) and the fat tissue index (FTI = FTM / height2). The values for LTI and FTI will be compared to a healthy reference population matched by age and sex. Values below the 10th percentile of the reference population will be considered clinically significant.

Résults were registered in the case report form (CRF).

Patient characteristics

All this information will be collected using two questionnaires given to one reference physician or nurse and the patient respectively.

The investigator identified diabetes (assumed to be present in patients using glucose lowering drugs or insulin), nephropathy, residual diuresis, comorbidities allowing the calculation of the Charlson score, numbers of antihypertensive drugs, hospitalization less than three months old, history of peritoneal dialysis and / or transplantation.

Concerning the daily practice of home dialysis the investigator identified ultrafiltration, blood flow, length of sessions, type of vascular access and creation date, the usual time of the session, the person performing the fistula puncture at home, needle type, frequent problem with connection, observance of dialysis sessions, date of installation at home The following biochemical parameters will be determined in the local laboratories from blood collected during the routine visit. Predialytic dosage: hemoglobin, hematocrit, platelets, leukocytes, urea, creatinine, serum iron, CST, ferritin, sodium, chlorine, potassium, magnesium, alkaline reserve, protidemia, albumin, prealbumin, CRP, PTH, calcium, phosphorus, BNP, B2-microglobulin. Postdialytic dosage: sodium, chlorine, potassium, alkaline reserve, urea, protidemia, B2-microglobulin.

New Kt/V measurement method

Conventionally in dialysis patients, the dialysis dose is represented by the formula kt / V, with: k= plasma clearance of urea; t= unit of time; V= volume of distribution of urea in dialysis patient.

The current assessment is Daugirdas2: Kt / V = -ln (R- (0.008 * t) + ((4 (3.5 * R)) * UF%), with: R= Urea after / Urea before; t= time of the session (hour); UF%= 100*/post-dialysis weight, Our current method therefore requires a plasma dosage of urea at the beginning and end of the session.

The investigator propose a new measurement method where the V will be obtained by impedancemetry and the t corresponds to the duration of the session. For k, the investigator rely on the fact that in vitro (27), at low dialysate flow rate, the saturation of the dialysate in urea is constant, and therefore that the k can be represented by the formula: k = ax Qd (with a: saturation constant and Qd: dialysate flow) Therefore, the investigator propose the following formula: Dialysis dose = a x Qd x t / V This is a new measurement method with important clinical relevance since it avoids two blood tests and two biological tests.

The investigator would therefore like to assume that the measure of kt / V would be equivalent between the formula the investigator would like to test and the conventional formula, either: a x Qd x t / V ≡ kt / V Daugirdas2