Developing Bioimpedance (BIA) as a Tool for Fluid Management in Peritoneal Dialysis Patients: A Validation Study

Hypothesis: The investigators hypothesize that regular monitoring of BIA adds value to the management of fluid status in PD patients

Objectives of the study: The objective is to show that in patients where the additional information of body composition is available to the clinician that the ECFv is maintained within pre-agreed limits, ~ 1 liter, over the observation period of 12 months.

SCIENTIFIC BACKGROUND:

Low peritoneal ultrafiltration, and by inference low sodium removal, is associated with worse outcomes in PD. Equally, excessive fluid removal is a risk factor for dehydration and loss of residual renal function. Current guidelines have advocated a daily UF volume of 1litre; their blunt application could lead to either inappropriate early loss of residual function or modality transfer. There is a significant need for evidence on how to best manage fluid status in PD patients, both in terms of an appropriate clinical strategy and also a simple but reproducible tool to guide clinicians in how to apply this strategy.

It is likely that BIA will become the standard tool to aid clinicians in assessing fluid status. It is simple to perform, intervention studies have demonstrated its ability to identify changes in fluid status in response to changes in therapy and it is a powerful predictor of patient survival. There is, however a clear need at this stage for proof of principle studies to establish its true potential for added value in the routine management of patients.

Body composition changes spontaneously with time on PD. Short term changes in hydration (specifically extracellular fluid volume, ECFv) combined with medium term changes in muscle and fat make it difficult for the clinician to be sure if fluid status is stable. It is anticipated that regular BIA measurements will aid the clinician in managing this problem over and above monitoring of weight and fluid status. By randomizing patients into two groups who have regular BIA measurements, one of which the BIA data is available to the clinician it will be possible to see if these spontaneous changes in body composition can be accounted for.