Changes of Renal Resistive Index in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy.

May 28, 2025 updated by: Maciej Piwoda, Uniwersytecki Szpital Kliniczny w Opolu

Changes of Renal Resistive Index in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy - Observational Study.

The aim of the study is to determine whether there is a correlation between changes in the renal resistive index and the restoration of kidney function in critically ill patients undergoing continuous renal replacement therapy.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

A significant number of critically ill patients experience acute kidney injury (AKI), an independent factor contributing to increased mortality. Prevention of AKI and monitoring kidney function are crucial. Commonly used markers such as serum creatinine and hourly diuresis are employed to assess AKI severity, but they are not ideal due to their late elevation in the disease course. Therefore, alternative methods for detecting and evaluating kidney dysfunction at an earlier stage are sought.

Previous studies have demonstrated a correlation between the risk of AKI and the resistive index of renal parenchymal arteries. Renal resistive index (RRI) is a parameter calculated from Doppler measurements, representing the difference between peak blood velocity during systole and end-diastolic velocity divided by peak systolic velocity [(Vs-Vd) /Vs]. In healthy adult kidneys, the RI typically ranges from 0.6 to 0.7. Changes in RRI can be observed much earlier than an increase in serum creatinine concentration and/or a decrease in hourly diuresis.

Some patients with acute kidney injury require renal replacement therapy. Continuous renal replacement therapy (CRRT) is commonly used in critically ill patients, causing less circulatory destabilization compared to intermittent therapies. However, adverse effects accompany renal replacement therapies, including thromboembolic complications, bleeding, infections, blood cell damage, altered drug pharmacokinetics, and loss of proteins and vitamins.

In addition to determining the appropriate initiation time for CRRT, identifying the optimal moment to end the treatment is crucial. CRRT is typically applied for several days, and during the procedure, it is challenging to ascertain whether renal function has improved and whether CRRT can be safely discontinued. The hypothesis is that there may be a correlation between changes in RRI and the recovery of kidney function. This may enable the early identification of patients who have regained kidney function, allowing for the earlier termination of CRRT.

In 1989, a study was conducted on children undergoing peritoneal dialysis due to AKI, showing a relationship between a decrease in RRI and the restoration of kidney function. However, no similar study has been conducted on adult patients undergoing continuous renal replacement therapy.

The planned project will be based on daily ultrasonographic examinations, measuring RRI of the arcuate and/or interlobar arteries of both kidneys.

Study Type

Observational

Enrollment (Estimated)

50

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Poland
    • Opolskie
      • Opole, Opolskie, Poland, 45-372
        • Recruiting
        • Department of Anesthesiology and Intensive Care, Uniwersytecki Szpital Kliniczny w Opolu
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

Adult ICU patients undergoing CRRT due to AKI

Description

Inclusion Criteria:

  • All ICU patients undergoing CRRT due to AKI

Exclusion Criteria:

  • age <18 years
  • pregnancy
  • history of chronic kidney disease in stage 4 or 5
  • post-kidney transplant status
  • mechanical circulatory support

  • occurrence of one or more conditions preventing reliable RRI measurement in both kidneys:

    • challenging technical conditions of ultrasound examination, hindering proper visualization of the kidney
    • post-kidney injury in grade III and higher, according to AAST
    • advanced parenchymal kidney pathology: atrophy, hypoplasia, cirrhosis, extensive ischemia (more than 2/3 of the parenchyma),
    • kidney diseases preventing parenchyma identification: advanced cancer (stage above T1 according to TNM), certain forms of polycystic kidney disease
    • inflammatory kidney diseases
    • obstructive uropathy
    • renal vascular pathologies: renal vein thrombosis, significant stenosis (>60%), and renal artery occlusion.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Acute Kidney Injury + CRRT

Critically ill patients admitted to the intensive care unit (ICU), undergoing continuous renal replacement therapy due to Acute Kidney Injury.

Diagnostic Test: Daily Doppler measurement of Renal Resistive Index
Diagnostic test: Measurement of Renal Resistive Index

The kidneys are preliminarily visualized in a 2D projection, followed by identifying interlobar or arcuate vessels using color Doppler. Flow measurements in these vessels are performed using pulsed-wave Doppler. Renal Resistive Index is determined over three cardiac cycles (five in the case of atrial fibrillation) in two different arteries, each in a different kidney section. Subsequently, measurements from each artery are averaged. If possible, the examination should be conducted bilaterally.

The investigators do not have access to previous measurements (each study is recorded on a separate card).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Relationship between changes in RRI and recovery of kidney function
Time Frame: on average from 1 to 3 weeks
The first ultrasound examination should be performed before the initiation of CRRT and, if not possible, within 24 hours of starting CRRT. Subsequently, the renal arteries will be assessed once a day during CRRT and after its completion until kidney function improves or there is a need for a return to renal replacement therapy. The return of kidney function is defined as a stable (increase <0.3 mg/dl/24h) or decreasing serum creatinine level in two consecutive tests conducted at intervals of at least 24 hours and an average hourly diuresis >0.5 ml/kg over the last 12 hours, with or without loop diuretics.
on average from 1 to 3 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Uniwersytecki Szpital Kliniczny w Opolu

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 19, 2023

Primary Completion (Estimated)

May 21, 2026

Study Completion (Estimated)

December 18, 2026

Study Registration Dates

First Submitted

December 1, 2023

First Submitted That Met QC Criteria

December 7, 2023

First Posted (Actual)

December 18, 2023

Study Record Updates

Last Update Posted (Actual)

June 3, 2025

Last Update Submitted That Met QC Criteria

May 28, 2025

Last Verified

May 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • RICRRT_USK

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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