Inter- and intradialytic fluid volume changes and vascular stiffness parameters in patients on hemodialysis

Background Whether fluid overload is associated with vascular stiffness parameters in hemodialysis (HD) patients has not been fully elucidated. We hypothesized that interdialytic fluid accumulation increases vascular stiffness parameters, which improves with intradialytic ultrafiltration. Methods Fluid overload and vascular stiffness parameters were assessed in 39 HD patients (20 with and 19 without fluid overload) and compared to 26 healthy controls. Fluid status was assessed 15 minutes before the mid-week HD session by bio-impedance spectroscopy. Following this, ambulatory pulse wave velocity (PWV) and augmentation index (Alx) were measured for 24 hours before another mid-week HD session and then for 5 hours starting 30 minutes before and ending 30 minutes after the session. Results HD patients had significant fluid overload compared to healthy controls (2.0 +/- 2.4 vs. -0.2 +/- 0.6 L; P<0.001) and baseline PWV was higher (10.3 +/- 1.7 vs. 8.8 +/- 1.4 m/s; P<0.001). There was no significant difference between PWV and Alx in fluid overloaded and non-fluid overloaded HD patients prior to, or during the HD session. Alx of non-fluid overloaded HD patients improved after the HD session (P = 0.04). Average 24-hour Alx was higher in fluid overloaded HD patients (P<0.001). Conclusions Inter- and intradialytic changes in fluid volume were only weakly related to vascular stiffness parameters in HD patients. Although there was a modest reduction in Alx in non-fluid overloaded HD patients after the dialysis session, fluid removal did not improve vascular stiffness parameters during the HD session. We speculate that the effect of fluid overload correction on vascular stiffness parameters requires long-term adjustments in the vasculature.

Automated summary

The association between fluid overload and vascular stiffness parameters in hemodialysis patients remains unclear. This study found that inter- and intra-dialytic changes in fluid volume had only weak correlations with vascular stiffness parameters. While a modest reduction in augmentation index (Alx) was observed in non-fluid overloaded patients after dialysis, fluid removal did not improve vascular stiffness parameters during the dialysis session. Long-term adjustments in the vasculature may be required for fluid overload correction to have an effect on vascular stiffness parameters.