Cardiovascular disease accounts for more than half of all deaths in the hemodialysis (HD) population. Although much of this mortality is associated with fluid overload (FO), FO is difficult to measure, and many HD patients have significant pulmonary congestion despite the absence of clinical presentation. Cohort studies have observed that FO, as measured by bioimpedance spectroscopy (BIS), correlates with mortality. Other studies have observed that lower sodium intake is associated with less fluid-related weight gain, improved hypertension, and survival. Whether sodium intake influences FO in HD patients as measured by BIS is not known.
The aims of the study were to determine the feasibility of assessing the impact of sodium restriction on body fluid composition as measured by BIS among patients with three levels of sodium intake and to determine if there are statistical and/or clinical differences in BIS measures across sodium intake groups.
We used a double-blinded randomized controlled trial design with three levels of sodium restriction, 2,400 mg per day, 1,500 mg per day, and unrestricted (control group), to test our aims. Forty-two HD patients from a tertiary acute care academic institution associated with three urban DaVita dialysis centers were enrolled. Participants remained in the inpatient center for 5 days and 4 nights and were randomly assigned to sodium intake groups. Body fluid composition was measured with BIS.
Recruitment, enrollment, and retention statistics supported the feasibility of the study design. Regression analyses showed that there were no statistically significant differences among sodium intake groups on any of the outcomes.
Our data suggest the need for additional research into the effects of sodium restriction on body fluid composition.
Maya N. Clark-Cutaia, PhD, ACNP-BC, RN, is Assistant Professor, Rory Meyers College of Nursing, New York University, New York. She was Lecturer in the Biobehevioral Health Sciences Department, the University of Pennsylvania, Philadelphia, when the research was completed.
Nathaniel Reisinger, MD, is Nephrology Fellow, Perelman School of Medicine, University of Pennsylvania, Philadelphia, and Hypertension Program, the Hospital of the University of Pennsylvania, Philadelphia.
Maria Rita Anache, BS, is Research Assistant, School of Osteopathic Medicine, Rowan University, Stratford, New Jersey.
Kara Ramos, BSN, is Research Assistant, School of Nursing, University of Pennsylvania, Philadelphia.
Marilyn S. Sommers, PhD, RN, FAAN, is Professor Emerita, School of Nursing, University of Pennsylvania, Philadelphia. She was the Lillian S. Brunner Professor of Medical-Surgical Nursing during the time that the work for this study was completed.
Raymond R. Townsend, MD, is Professor, Perelman School of Medicine, University of Pennsylvania, Philadelphia, and Director, Hypertension Program, the Hospital the University of Pennsylvania, Philadelphia.
Gary Yu, DrPH, MPH, is Associate Research Scientist, Rory Meyers College of Nursing, New York University, New York.
Jamison Fargo, PhD, MS-EPI, is Professor, Utah State University, Logan.
Accepted for publication July 4, 2018.
The authors acknowledge the individual contributions of Ene Anteyi, MPH, BS, Sinja Kriete, student researcher, Christine Lin, BSN, Kelly McGuigan, BS, Harsh Patel, Azwad Rahman, BS, and Pranati Sreepathy, BS, as well as the medical staff of the DaVita dialysis centers and inpatient research unit.
This study was supported through Grant NIH-K23NR015058 received by Maya N. Clark, PhD, ACNP-BC, RN, from the National Institute of Nursing Research at the National Institutes of Health. The National Institute of Nursing Research did not have any role in the study design; collection, analysis, or interpretation of the data; report development; or publication submission.
The study was approved by the Institutional Review Board at the University of Pennsylvania.
Clinicaltrials.gov Identifier: NCT02778516. Sodium-Restricted Diets and Symptoms in End-Stage Renal Disease: An RCT.
The authors have no conflicts of interest to report.
Corresponding author: Maya N. Clark-Cutaia, PhD, ACNP-BC, RN, Rory Meyers College of Nursing, New York University, 433 First Avenue, Room 664, New York, NY 10010 (e-mail: firstname.lastname@example.org).