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NCT Number: NCT07803029

Bioimpedance Spectroscopy (BIS): Fluid Changes in Hemodialysis Patients

In connection with dialysis treatment, fluid and salt balance changes. Some kidney disease patients experience fluid accumulation in the body and need to have excess fluid removed via the dialysis machine. Others have too little fluid in their bodies and experience general symptoms. The amount of fluid that needs to be removed is an individual assessment and can be difficult to determine. Today, fluid removal is determined based on signs such as water in the lungs, swollen legs, and blood pressure. By using a so-called bioimpedance spectroscopy (BIS) device, it os possible measure how much fluid is in the body. However, the calculations that BIS devices use are developed for healthy individuals and do not work optimally during dialysis. Therefore, the investigators will use the actual measurements and compare them with fluid extraction and weight changes to examine their relationship. Hemodialysis patients with ultrafiltration on 3 consecutive dialysis days in order to investigate whether there is a difference in measurements after the long dialysis break and whether the measurements are the same when you are being drawn to your dry weight are included. Other patients without fluid removed during dialysis will be investigated once. I the study the absolute blood volume is also measured, that is, how much fluid is in the bloodstream. This is also an expression of the body's total fluid volume. By combining the various measurements, the study will gain increased knowledge about your hydration status. If the measurement methods have sufficient precision, the use of BIS and measurement of total blood volume may contribute to a more accurate determination of your dry weight.

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Key information

Conditions

Hemodialysis Body Weight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Aarhus University Hospital

Aarhus, Central Denmark, 8200, Denmark

Location status: Recruiting

Location contact

Per Ivarsen, MD

CONTACT

[email protected]

+457845000

Per Ivarsen, MD

PRINCIPAL_INVESTIGATOR

CONTACT

[email protected]

About this study

To investigate whether raw impedance data from BIS measurements can be used as a tool to estimate changes in fluid status in HD patients. Accuracy is low when using prediction equations that are integrated into the individual BIS device. This challenges the application in clinical practice. Furthermore, the prediction equation is not available for most devices. Small studies suggest greater accuracy when using raw data, which could make BIS measurements clinically applicable. Detailed purpose. To examine whether raw impedance data from BIS measurements can be used as a tool to estimate changes in fluid status in HD patients.

  • Ensure consistency in measurements of raw impedance data (Phase angle, RE, RI, R∞, and Cm) between different BIS devices (here: Fresenius BCM®, SFB7®, and SOZO® from ImpediMed).
  • Compare intradialytic ∆RE, ∆R∞, and ∆Cm against changes in absolute blood volume, BP, weight, and fluid removal in HD patients with fluid removal.
  • Is the phase angle consistent over the 3 dialysis days in a week for center dialysis patients with fluid retention?
  • Compare intradialytic ∆RE, ∆R∞, and ∆Cm against changes in absolute blood volume, blood pressure, and weight in hemodialysis patients without fluid retention.
  • Compare intradialytic ∆blood pressure, ∆weight, ∆ABV, fluid retention, and BIS measured changes (∆RE, ∆R∞, ∆Cm) for patients undergoing home hemodialysis with patients undergoing center hemodialysis.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Hemodialysis for more than 3 month Hemodynamic stabile during a dialysis session

-

Exclusion criteria

  • Amputated limbs.
  • Pregnant.
  • Extremity palsy and paralysis.
  • Implanted electronic device (e.g., pacemaker or ICD).
  • Regular use of dialysate sodium proliferation.
  • Hip, knee and shoulder prosthesis.
  • Dialysis fistula in both arms.
  • Inability to give informed consent.
  • History of discontinuation of dialysis treatment prematurely.

Treatment and study plan

Bioimpedance analysis

Device

Comparing the perfomance of original data from 3 different bioimpedance apparatur and test there precision and accurary compared to ultrafiltration. And whether the performance of measuring absolut blood volume is better

Primary outcomes

  1. Changes in BIS measured resistance and fluid removed

    Time frame: From enrollment to the end of the dialysis session

    To investigate whether raw impedance data from BIS measurements can be used as a tool to estimate changes in fluid status in HD patients before and after a hemodialysis session of 4 hours duration. Weight loss during a hemodialysis session is equivalent to fluid removed. The meausement are don for up to oen week

    • To determine consistency in measurements of raw impedance data (Ω) between different BIS devices (here: Fresenius BCM ®, SFB7 ® and SOZO ® from Imped-iMed).
    • Change in raw impedance data (Ω) during a hemodialysis session of 4 hours
    • Degree of ultrafiltrating (ml) a hemodialysis session of 4 hours
    • Change in absolute blood volume (ml) during a hemodialysis session of 4 hours
    • In a subset of patients test if the length of the of pause (days) between hemodialysis session influence the raw impedance measurements.

Study contacts

Contact information is provided by the study sponsor or research team.

Per Ivarsen, MD

CONTACT

[email protected]

+457845000

Sponsors and collaborators

Lead sponsor

Per Ivarsen

Other

Registry information

Official study title

Bioimpedance Spectroscopy (BIS): Analysis of Changes in Fluid Status in Hemodialysis Patients

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Sep 3, 2026
Registry last updated
Sep 3, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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