Conventional Hemodialysis vs. Short Daily Hemodialysis (6 Days / Week) and Mechanisms of Blood Pressure Control

Summary

More than 80% of patients with end stage renal disease have hypertension; 70% of whom are poorly controlled using conventional Hemodialysis therapy. An expanded extracellular fluid volume and an increase in peripheral vascular resistance as a result of hemodynamic/trophic effects of an increased sympathetic nerve activity, angiotensin II, asymmetrical dimethyl arginine, and decreased nitric oxide are the most frequently quoted mechanisms contributing to hypertension in this population. The intermittent nature of conventional hemodialysis treatments (4 hours, 3 days/week) results in the majority of patients having a sustained expansion of the extracellular fluid volume that likely contributes to the activation of neurohormonal pathways. However, daily therapy including short daily hemodialysis (2 hours, 6 days/week) and nocturnal hemodialysis (6-8 hours, 5-6 days/week) improve or even normalize blood pressure. Short daily hemodialysis appears to improve blood pressure secondary to a reduction in extracellular fluid volume (7,8) whereas the improvement in blood pressure with nocturnal hemodialysis occurs by a reduction in peripheral vascular resistance (8,9,10). This is consistent with the Katzarski et al experience (7-8 hours, 3 days/week) and one randomized controlled trial in which blood pressure control was due to normalization of extracellular fluid volume in some patients and a reduction in peripheral vascular resistance in others. The majority of the studies in daily dialysis are observational, do not include a run-in period to optimize blood pressure management and have not explored the mechanisms of improvement in blood pressure in detail. We have designed a 9 month study to determine if the mechanism by which short daily hemodialysis is associated with an improvement in blood pressure control is secondary to changes in sympathetic nervous system activity and/ or extracellular fluid volume. Additionally we would like to explore the potential impact of short daily dialysis, compared to conventional dialysis, on markers of inflammation and oxidative stress in detail.

Conditions

• End Stage Renal Disease

Interventions

PROCEDURE

Microneurography

Muscle sympathetic nerve activity measurement will be obtained using microneurography. Approximately 10-20% of microneurography recordings are not interpretable due to technical problems. For this reason, blood samples will be collected at the same time that the microneurography is to be done. These test will be done at 3 time points throughout the study.

PROCEDURE

Bioimpedance testing

bioimpedance measurement of extracellular fluid volume will be measured at the end of each 3 month period. This test will be done at 3 time points throughout the study.

Sponsors & Collaborators

• Heart and Stroke Foundation of Ontario

  collaborator OTHER

• University of Ottawa

  collaborator OTHER

• Ottawa Hospital Research Institute

  lead OTHER

Principal Investigators

• Deborah Zimmerman, MD · Ottawa Hospital Research Institute

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2007-09-30

Primary Completion

2011-06-30

Completion

2012-06-30

Countries

• Canada

Study Locations