Assessment of Hydration Status in Peritoneal Dialysis Patients: Validity, Prognostic Value, Strengths, and Limitations of Available Techniques

Abstract

Background: The majority of patients undergoing peritoneal dialysis (PD) suffer from volume overload and this overhydration is associated with increased mortality. Thus, optimal assessment of volume status in PD is an issue of paramount importance. Patient symptoms and physical signs are often unreliable indexes of true hydration status. Summary: Over the past decades, a quest for a valid, reproducible, and easily applicable technique to assess hydration status is taking place. Among existing techniques, inferior vena cava diameter measurements with echocardiography and natriuretic peptides such as brain natriuretic peptide and N-terminal pro-B-type natriuretic peptide were not extensively examined in PD populations; while having certain advantages, their interpretation are complicated by the underlying cardiac status and are not widely available. Bioelectrical impedance analysis (BIA) techniques are the most studied tool assessing volume overload in PD. Volume overload assessed with BIA has been associated with technique failure and increased mortality in observational studies, but the results of randomized trials on the value of BIA-based strategies to improve volume-related outcomes are contradictory. Lung ultrasound (US) is a recent technique with the ability to identify volume excess in the critical lung area. Preliminary evidence in PD showed that B-lines from lung US correlate with echocardiographic parameters but not with BIA measurements. This review presents the methods currently used to assess fluid status in PD patients and discusses existing data on their validity, applicability, limitations, and associations with intermediate and hard outcomes in this population. Key Message: No method has proved its value as an intervening tool affecting cardiovascular events, technique, and overall survival in PD patients. As BIA and lung US estimate fluid overload in different compartments of the body, they can be complementary tools for volume status assessment.

The Association of Circulating CD14++CD16+ Monocytes, Natural Killer Cells and Regulatory T Cells Subpopulations With Phenotypes of Cardiovascular Disease in a Cohort of Peritoneal Dialysis Patients

“…All patients underwent bioimpedance analysis of body composition and fluid status using Fresenius Body Composition Monitor (BCM) for determination of overhydration (OH), extracellular water (ECW), intracellular water (ICW), total body water (TBW) content and the OH/ECW index, simultaneously with analysis of immune cell subsets ( 13 ). A lung ultrasound examination (Vscan™ GE Healthcare's) was likewise simultaneously performed with estimation of extravascular lung water by counting vertical “comets” or “B-lines and their sum number ( 14 , 15 ).…”

The association between office blood pressure and fluid status using bioimpedance spectroscopy in stable continuous ambulatory peritoneal dialysis patients

“…The clinical examination has poor diagnostic accuracy with poor reproducibility and high interobserver variation [ 9 ]. It was reported that up to a third of patients labelled as being euvolemic by clinical examination were in fact fluid overloaded when assessed by more accurate methods [ 10 ].…”

“…As a result, clinicians have searched for alternative methods to accurately assess the volume status in PD patients. These include biomarkers such as atrial and brain natriuretic peptides, inferior vena cava diameter and lung ultrasound [ 9 ]. However, bioimpedance techniques have gained popularity in recent years because it is non-invasive, easily applied at the bedside and has been validated against gold standard techniques such as deuterium dilution methods and dual-energy X-ray absorptiometry [ 12 ].…”

Dysnatremias in Chronic Kidney Disease: Pathophysiology, Manifestations, and Treatment

“…Various other methods, which have been applied for evaluating ECV and TBW in dialysis patients, have limitations ( 98 , 99 ). ECV associated with optimal perfusion of vital organs, i.e., with the effective arterial blood volume, may vary from the normal value in disease states, e.g., in congestive heart failure ( 100 ).…”

“…ECV associated with optimal perfusion of vital organs, i.e., with the effective arterial blood volume, may vary from the normal value in disease states, e.g., in congestive heart failure ( 100 ). Measurement of TBW and ECV by bioimpedance and simultaneous performance of lung ultrasonography to evaluate the extravascular lung ECV is considered a promising method for estimating the dry weight ( 98 , 101 , 102 ). Careful clinical evaluation of the fluid status of patients on hemodialysis is imperative ( 103 , 104 ).…”