Evaluation of Volume Status in Peritoneal Dialysis Patients

Overview

Patients with kidney failure on dialysis have a much higher risk of developing cardiovascular disease as compared to the general population. Recently, two large studies have shown that increasing the amount of dialysis does not decrease cardiovascular disease. It is known that retaining too much fluid leads to high blood pressure and thickening of the heart wall. Peritoneal dialysis is a method of home dialysis which allows dialysis patients autonomy and independence. This study will measure blood levels of a protein called N-BNP and measure the extent of body fluid by a machine called a bioimpedance analyzer. This device administers an undetectible electric current which distributes throughout total body water. The relationship between these tests and the clinical presence of volume expansion will be assessed. In addition, the extent of total body fluid and it's impact on heart attacks, heart failure and stroke will be determined.

Patients with end-stage renal disease (ESRD) have a higher risk than the general population of developing premature cardiovascular disease; the reasons for this are complex. Two recent randomized controlled trials in peritoneal dialysis patients have demonstrated that targeting patients to higher dialysis clearance values is not associated with a reduction in mortality. It is known that patients on peritoneal dialysis are more likely to be volume expanded, develop left ventricular hypertrophy, and have inadequate blood pressure relative to patients on hemodialysis. As a result there has been increased attention on the role of fluid management in reducing the risk of developing congestive heart failure and other adverse cardiovascular events in peritoneal dialysis patients. Extracellular fluid volume and total body water can be accurately assessed with multi-frequency bioimpedance analysis (BIA). Estimation of volume expansion by measuring the natriuretic peptide N-BNP produced by cardiac tissue in response to ventricular wall stretch can also be used. The purpose of this study is to determine whether volume status, as measured by BIA and N-BNP levels, correlates with clinical volume assessment, cardiovascular outcomes, peritoneal membrane transport properties and markers of inflammation such as serum albumin and C-reactive protein.