Acute Kidney InjuryNCT06174610
Changes of Renal Resistive Index in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy.
An observational study of Acute Kidney Injury, run by Uniwersytecki Szpital Kliniczny w Opolu at 1 site in Poland.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Acute Kidney Injury
- What is being tested?
- Measurement of Renal Resistive Index
- How many people
- 50 participants
- Where
- 1 sitePoland
- Study dates
- 19 Dec 2023to 18 Dec 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Adult ICU patients undergoing CRRT due to AKI
Who may be able to join
- All ICU patients undergoing CRRT due to AKI
Who cannot join
- 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:
Show all 13Show fewer
- 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.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Poland1 site, 1 recruiting
- Recruiting
Department of Anesthesiology and Intensive Care, Uniwersytecki Szpital Kliniczny w Opolu
Opole, Opole Voivodeship, 45-372
Maciej Piwoda, MD, 048774520302, maciej.piwoda@usk.opole.pl
About this study
Official title: 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.
Read the 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.
- Conditions
- Acute Kidney Injury
- Being tested
- Measurement of Renal Resistive Index
- Keywords
- Acute Kidney Injury (AKI), Continous Renal Replacement Therapy (CRRT), Critical Care, Renal Resistive Index (RRI)
- Medical subject headings
- Acute Kidney Injury
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Measurement of Renal Resistive IndexDiagnostic test
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).
| Study group | Role | What they receive |
|---|---|---|
| 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 Receives: Diagnostic Test: Measurement of Renal Resistive Index |
What is being measured
The primary outcome is the main question the study is designed to answer.
Relationship between changes in RRI and recovery of kidney function
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.
Measured: on average from 1 to 3 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Dec 2023
- Study start19 Dec 2023
- Primary completion21 May 2026 (estimated)
- Study completion18 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Acute Kidney InjuryStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Uniwersytecki Szpital Kliniczny w Opolu
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Maciej Piwoda, Uniwersytecki Szpital Kliniczny w Opolu
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06174610
- Sponsor's protocol ID
- RICRRT_USK
- Status last verified
- May 2025
- First submitted
- 1 Dec 2023
- Last updated
- 3 Jun 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Patriquin HB, O'Regan S, Robitaille P, Paltiel H. Hemolytic-uremic syndrome: intrarenal arterial Doppler patterns as a useful guide to therapy. Radiology. 1989 Sep;172(3):625-8. doi: 10.1148/radiology.172.3.2672090.
PubMed 2672090Katulka RJ, Al Saadon A, Sebastianski M, Featherstone R, Vandermeer B, Silver SA, Gibney RTN, Bagshaw SM, Rewa OG. Determining the optimal time for liberation from renal replacement therapy in critically ill patients: a systematic review and meta-analysis (DOnE RRT). Crit Care. 2020 Feb 13;24(1):50. doi: 10.1186/s13054-020-2751-8.
PubMed 32054522Fernandez SN, Santiago MJ, Gonzalez R, Lopez J, Solana MJ, Urbano J, Lopez-Herce J. Changes in hemodynamics, renal blood flow and urine output during continuous renal replacement therapies. Sci Rep. 2020 Nov 27;10(1):20797. doi: 10.1038/s41598-020-77435-x.
PubMed 33247145Fernandez SN, Lopez J, Gonzalez R, Solana MJ, Urbano J, Aguado A, Lancharro A, Lopez-Herce J, Santiago MJ. Doppler ultrasound in the assessment of renal perfusion before and during continuous kidney replacement therapy in the pediatric intensive care unit. Pediatr Nephrol. 2022 Dec;37(12):3205-3213. doi: 10.1007/s00467-022-05428-1. Epub 2022 Mar 14.
PubMed 35286455Ninet S, Schnell D, Dewitte A, Zeni F, Meziani F, Darmon M. Doppler-based renal resistive index for prediction of renal dysfunction reversibility: A systematic review and meta-analysis. J Crit Care. 2015 Jun;30(3):629-35. doi: 10.1016/j.jcrc.2015.02.008. Epub 2015 Feb 24.
PubMed 25746587
Study at a glance
From the registry record, last updated by the sponsor on 3 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Changes of Renal Resistive Index in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy - Observational Study.
- ClinicalTrials.gov ID
- NCT06174610
- Acronym / sponsor ID
- RICRRT_USK
- Conditions
- Acute Kidney Injury
- Keywords
- Acute Kidney Injury (AKI), Continous Renal Replacement Therapy (CRRT), Critical Care, Renal Resistive Index (RRI)
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 50 participants (estimated)
- Lead sponsor
- Uniwersytecki Szpital Kliniczny w OpoluUniversity, hospital or other
- Study start
- 19 Dec 2023 (actual)
- Primary completion
- 21 May 2026 (estimated)
- Study completion
- 18 Dec 2026 (estimated)
- First posted
- 18 Dec 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Acute Kidney Injury + CRRT | – | Diagnostic Test: Measurement of Renal Resistive IndexCritically 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 |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult ICU patients undergoing CRRT due to AKI
Key inclusion criteria (1 listed)
- All ICU patients undergoing CRRT due to AKI
Key exclusion criteria (13 listed)
- age <18 years
- pregnancy
- history of chronic kidney disease in stage 4 or 5
- post-kidney transplant status
- mechanical circulatory support
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Measurement of Renal Resistive IndexThe 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). | Diagnostic test | Acute Kidney Injury + CRRT |
Primary outcome
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.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 3 Jun 2025.
- Background: PubMed 2672090Patriquin HB, O'Regan S, Robitaille P, Paltiel H. Hemolytic-uremic syndrome: intrarenal arterial Doppler patterns as a useful guide to therapy. Radiology. 1989 Sep;172(3):625-8. doi: 10.1148/radiology.172.3.2672090.
- Background: PubMed 32054522Katulka RJ, Al Saadon A, Sebastianski M, Featherstone R, Vandermeer B, Silver SA, Gibney RTN, Bagshaw SM, Rewa OG. Determining the optimal time for liberation from renal replacement therapy in critically ill patients: a systematic review and meta-analysis (DOnE RRT). Crit Care. 2020 Feb 13;24(1):50. doi: 10.1186/s13054-020-2751-8.
- Background: PubMed 33247145Fernandez SN, Santiago MJ, Gonzalez R, Lopez J, Solana MJ, Urbano J, Lopez-Herce J. Changes in hemodynamics, renal blood flow and urine output during continuous renal replacement therapies. Sci Rep. 2020 Nov 27;10(1):20797. doi: 10.1038/s41598-020-77435-x.
- Background: PubMed 35286455Fernandez SN, Lopez J, Gonzalez R, Solana MJ, Urbano J, Aguado A, Lancharro A, Lopez-Herce J, Santiago MJ. Doppler ultrasound in the assessment of renal perfusion before and during continuous kidney replacement therapy in the pediatric intensive care unit. Pediatr Nephrol. 2022 Dec;37(12):3205-3213. doi: 10.1007/s00467-022-05428-1. Epub 2022 Mar 14.
- Background: PubMed 25746587Ninet S, Schnell D, Dewitte A, Zeni F, Meziani F, Darmon M. Doppler-based renal resistive index for prediction of renal dysfunction reversibility: A systematic review and meta-analysis. J Crit Care. 2015 Jun;30(3):629-35. doi: 10.1016/j.jcrc.2015.02.008. Epub 2015 Feb 24.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Department of Anesthesiology and Intensive Care, Uniwersytecki Szpital Kliniczny w Opolu
Opole, Poland
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Acute Kidney Injury, run by Uniwersytecki Szpital Kliniczny w Opolu at 1 site in Poland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 13 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 3 Jun 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Poland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Relationship between changes in RRI and recovery of kidney function (time frame: on average from 1 to 3 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06174610, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 3 Jun 2025; AzTrials last refreshed its copy on 7 Nov 2026.