Effect of Plasma Sodium Concentration on Blood Pressure Regulators During Hemodialysis

Is the Lower Incidence of Intradialytic Hypotension During Hemocontrol Dialysis in Comparison With Standard Hemodialysis Attributable to Enhanced to Higher Plasma Vasopressin Levels or to Enhanced Sympathetic Activity and/or to Less Nitric Oxide Production

Intradialytic hypotension (IDH) is a frequent and serious complication that may occur during hemodialysis treatment. The investigators and others have shown that the Hemocontrol biofeedback system is associated with improved hemodynamic stability. Hemocontrol is a technique that guides the patients' blood volume along a pre-set trajectory by continuously adjusting the ultrafiltration rate and dialysate conductivity. In a recent pilotstudy, the investigators found significantly higher plasma vasopressin levels during the first hour of dialysis with Hemocontrol in comparison with standard hemodialysis. Increased vasopressin levels may contribute to intradialytic hemodynamic stability during hemodialysis by enhanced vasoconstriction. These results, however, did not prove directly that the improved hemodynamic stability with Hemocontrol is indeed caused by higher initial plasma vasopressin levels. Alternative explanations might be that 1) the higher initial plasma sodium levels with Hemocontrol dialysis enhance activity of the sympathetic nervous system directly, causing vasoconstriction and thereby improved hemodynamic stability and/or 2) that the higher initial plasma levels of sodium in Hemocontrol inhibit the release of nitric oxide by the vascular endothelium. Another goal of this study is to investigate whether vasopressin is removed with hemodialysis.

Each participating patient underwent one standard hemodialysis and one hemodialysis with Hemocontrol in random order, both 4 hours in total duration. The Hemocontrol system guides the patients' blood volume along a predefined ideal relative blood volume trajectory, by continuously adjusting ultrafiltration volume and dialysate sodium concentration.

Each participating patient underwent one standard hemodialysis and one hemodialysis with Hemocontrol in random order, both 4 hours in total duration. During standard hemodialysis, a constant ultrafiltration rate and dialysate conductivity was used.

Before, after 30, 60, 120 and 180 minutes and after dialysis blood is withdrawn from the dialysis line to determine plasma levels of vasopressin.

Inclusion Criteria: Age ≥18 years A thrice-weekly 4 hours hemodialysis schedule Dialysis on an arteriovenous fistula A usual interdialytic weight gain of ≥2.0 kg Exclusion Criteria: Age<18 years Dialysis duration of <4 or >4 hours Dialysis frequency of <3 or >3 times a week Dialysis on a central venous catheter A usual interdialytic weight gain <2 kg

Ettema EM, Kuipers J, van Faassen M, Groen H, van Roon AM, Lefrandt JD, Westerhuis R, Kema IP, van Goor H, Gansevoort RT, Gaillard CAJM, Franssen CFM. Effect of plasma sodium concentration on blood pressure regulators during hemodialysis: a randomized crossover study. BMC Nephrol. 2018 Aug 22;19(1):214. doi: 10.1186/s12882-018-0997-z.