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NCT Number: NCT07293936

Post-Filter Hematocrit

Filter clotting is a major complication of continuous renal replacement therapy (CRRT), resulting in blood loss, reduced treatment efficacy, and increased cost. One modifiable factor associated with filter clotting is filtration fraction (FF), or the proportion of plasma water being removed from the blood over the course of the filter. In convention, a cutoff of FF<20-30% has been used to prevent hemofilter clotting, but no evidence correlating FF with hemofilter clotting has been documented. Some experts have proposed that post-filter hematocrit (Hct) could be a more direct marker for determining hemofilter clotting risk, but evidence supporting clinical utility of this marker is lacking.

HCTpost=HCTpre/(FF(HCTpre-1)+1)

In our proposed validation study, we hope to determine whether our formula for post-filter Hct provides accurate results when compared to measured values. The information obtained from this study will potentially justify the use of utilizing the formula in future studies.

The procedure of this study is collecting blood samples from the post-filter lines of patients on CRRT at different time points and different flow rates. This will be considered the "measured post-filter hematocrit" which will then be compared to the calculated formula above, using the other values obtained from daily labs (for pre-filter hematocrit) and CRRT machine settings.

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Key information

Conditions

Continuous Renal Replacement Therapy Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Hemofilter Clotting Kidney Diseases Male Urogenital Diseases Renal Failure Renal Insufficiency Urogenital Diseases Urologic Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Iowa Hospitals and Clinics

Iowa City, Iowa, 52242, United States

Location status: Recruiting

Location contact

Gwyndolyn M Radford, MD

CONTACT

[email protected]

319-384-9668

About this study

This investigational study is listed as "other" because it is a validation study comparing two measurement methods-comparing a calculated versus a machine-measured post-filter hematocrit- and is typically classified as a cross-sectional investigational study in the context of diagnostic or method comparison research.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • patients initiated on CRRT age equal than or greater to 18 years of age

Exclusion criteria

  • patients on ECMO

Treatment and study plan

Calculated Post-Filter Hematocrit

Other

using the formula: HCTpost=HCTpre/(FF(HCTpre-1)+1)

Measured Post-Filter Hematocrit

Other

Measured from blood sample taken from CRRT machine

Primary outcomes

  1. Agreement between measured and calculated post-filter hematocrit values.

    Time frame: Participation begins at consent and includes a single study procedure in which four post-filter blood samples are collected over ~40 minutes. Participation ends after the final draw. Generally, no longer than 1 day.

    Use Bland-Altman analysis to assess agreement and quantify bias and limits of agreement. Calculate correlation coefficients (Pearson or Spearman) to evaluate the strength of association.

Secondary outcomes

  1. Analyze the impact of CRRT settings on discrepancies between measured and calculated Filtration Fraction

    Time frame: Participation begins at consent and includes a single study procedure in which four post-filter blood samples are collected over ~40 minutes. Participation ends after the final draw. Generally, no longer than one day.

    How do different settings (e.g., Q_B, Q_UF, Q_prefilter, Q_postfilter) on the machine affect the discrepancies (if there are any) between calculated and measured filtration fraction. Will be using change in post-filter hematocrit values as the measured filtration fraction and comparing to calculated filtration fraction using standard flow-rate derived formula used in practice.

  2. Subgroup analysis based on patient-specific factors

    Time frame: Participation begins at consent and includes a single study procedure in which four post-filter blood samples are collected over ~40 minutes. Participation ends after the final draw.

    Post-filter hematocrit values will be stratified and compared across subgroups defined by baseline pre-filter hematocrit category, anticoagulation strategy (e.g., citrate vs. heparin vs. none), and blood-flow rate category. The metric reported will be the mean post-filter hematocrit within each subgroup and the between-group differences.

Study contacts

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

Benjamin R Griffin, MD

CONTACT

[email protected]

5073631404

Gwyndolyn M Radford, MD

CONTACT

[email protected]

7858179620

Sponsors and collaborators

Lead sponsor

Gwyndolyn M. Radford

Other

Registry information

Official study title

Validation of a Post-Filter Hematocrit Calculation Formula: A Comparative Analysis With Measured Post-Filter Hematocrit Values

Acronym: CRRTHCT

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Dec 19, 2025
Registry last updated
Dec 19, 2025

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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