The Association between Arterial Stiffness and Fluid Status in Peritoneal Dialysis Patients

OBJECTIVES: In this study our aim was to evaluate the relationship between degree of fluid status and arterial stiffness measured by pulse wave velocity (PWV) in peritoneal dialysis (PD) patients. Fluid status was determined by different methods including fluid overload measured by bioimpedance (Body Composition Monitor, BCM), calf normalized resistivity (CNR), plasma N-terminal fragment of B-type natriuretic peptide (NT-proBNP) and extracellular to intracellular water ratio (ECW/ICW). METHODS: Sixty PD patients were evaluated. They were stratified into normo- and hypervolemic groups according to their fluid overload (FO). CNR was calculated from resistance at 5 kHz using calf bioimpedance spectroscopy. Arterial stiffness was assessed by PWV. Additionally, all patients underwent transthoracic echocardiography and had levels of NT-proBNP measured. RESULTS: PWV was higher in the hypervolemic compared to normovolemic patients (9.99 ± 2.4 m/sec vs 7.48 ± 2.3 m/sec, p < 0.001). Hypervolemic patients had higher NT-proBNP levels (3065 ± 981 pg/mL vs 1095 ± 502 pg/mL, p < 0.001), a higher ratio of ECW/ICW; (0.93 ± 0.11 vs 0.81 ± 0.08, p < 0.001) and lower CNR (13.7 ± 2.4 vs 16.0 ± 3.3 W m(3)/kg(*)10(-2), p = 0.005). NT-pro BNP level, ECW/ICW ratio, relative FO, and left ventricular (LV) mass index were positively and CNR negatively correlated with PWV. Relative FO and CNR independently predicted PWV in multivariate analysis adjusted for age, duration of PD, body mass index and mean arterial pressure. CONCLUSIONS: Arterial stiffness is increased in fluid-overloaded PD patients. Our results indicated that fluid status is an independent predictor of PWV.