Assessment of Renal Perfusion Using Ultrasound and Near-Infrared Spectroscopy in Patients Undergoing Minimally Invasive Abdominal Surgery (RRI-NIRS)

June 3, 2026 updated by: Lyudmila Martynenko Aydogdu, Istanbul University - Cerrahpasa

Prospective Observational Evaluation of Renal Perfusion Using Doppler Ultrasonography and Near-Infrared Spectroscopy in Patients Undergoing Elective Minimally Invasive Abdominal Surgery

This prospective observational study aims to evaluate renal perfusion in adult patients undergoing elective minimally invasive abdominal surgery. Renal perfusion will be assessed using two non-invasive monitoring techniques: Doppler ultrasonography-derived Renal Resistive Index (RRI) and Near-Infrared Spectroscopy (NIRS)-derived renal regional oxygen saturation (rSO₂).

Measurements will be obtained at predefined perioperative time points, including after induction of anesthesia, during pneumoperitoneum, before extubation, and during the early postoperative period. Perioperative changes in renal perfusion parameters will be analyzed and correlated with clinical variables such as intra-abdominal pressure, pneumoperitoneum duration, hemodynamic parameters, fluid administration, urine output, and postoperative renal function.

The study also aims to investigate the relationship between intraoperative renal perfusion changes and the development of postoperative acute kidney injury. The findings may contribute to improved perioperative monitoring and optimization of renal perfusion during minimally invasive abdominal surgery.

Study Overview

Status

Recruiting

Conditions

Detailed Description

Minimally invasive abdominal surgery has become increasingly common because of reduced surgical trauma, faster recovery, and lower postoperative morbidity compared with conventional open surgery. However, laparoscopic procedures require the creation of pneumoperitoneum, which may increase intra-abdominal pressure and adversely affect renal blood flow, renal oxygen delivery, and kidney function.

Renal hypoperfusion during surgery may contribute to postoperative renal dysfunction and acute kidney injury (AKI). Traditional indicators of renal injury, such as serum creatinine and urine output, often fail to detect early changes in renal perfusion. Therefore, reliable non-invasive methods for real-time assessment of renal perfusion are needed.

Doppler ultrasonography-derived Renal Resistive Index (RRI) and Near-Infrared Spectroscopy (NIRS)-derived regional renal oxygen saturation (rSO₂) are promising techniques for evaluating renal perfusion and oxygenation. Both methods provide non-invasive, bedside assessment and may allow early detection of perfusion abnormalities before conventional markers become abnormal.

This prospective single-center observational study will evaluate perioperative renal perfusion in adult patients undergoing elective minimally invasive abdominal surgery. Renal perfusion measurements will be obtained using Doppler ultrasonography and NIRS at predefined perioperative time points, including after induction of anesthesia, during pneumoperitoneum, before extubation, and during the early postoperative period.

Demographic characteristics, comorbidities, baseline renal function, intraoperative hemodynamic variables, pneumoperitoneum duration and pressure, fluid administration, urine output, blood loss, ventilatory parameters, and postoperative renal function will be recorded. Associations between perioperative renal perfusion parameters and postoperative renal outcomes, including acute kidney injury, will be investigated.

The findings of this study may improve understanding of perioperative renal perfusion changes during minimally invasive abdominal surgery and contribute to the development of strategies for optimizing renal protection and perioperative patient management

Study Type

Observational

Enrollment (Estimated)

51

Contacts and Locations

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

Study Contact

Study Locations

  • Turkey (Türkiye)
      • Istanbul, Turkey (Türkiye), 34320
        • Recruiting
        • Istanbul University Cerrahpaşa Faculty of Medicine
        • 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

Non-Probability Sample

Study Population

Adult patients aged 18-80 years with ASA physical status I-III undergoing elective minimally invasive abdominal surgery at Istanbul University-Cerrahpaşa Faculty of Medicine. Patients will be prospectively evaluated for perioperative renal perfusion using Doppler ultrasonography and Near-Infrared Spectroscopy (NIRS).

Description

Inclusion Criteria:

  • Patients aged 18 to 80 years
  • Patients with ASA physical status I, II, or III
  • Patients undergoing elective minimally invasive abdominal surgery for any reason
  • Patients whose expected surgical duration is longer than 1 hour

Exclusion Criteria:

  • Body mass index greater than 35 kg/m²
  • Severe respiratory system disease
  • Severe heart failure, NYHA class III-IV
  • Presence of a cardiac pacemaker or cardiac defibrillator implant
  • Progressive neuromuscular disease
  • High intra-abdominal pressure
  • Sudden deterioration of general condition
  • Incomplete clinical or laboratory data
  • Refusal to participate in the study
  • Conversion to open surgery

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
Elective Minimally Invasive Abdominal Surgery Patients
Adult patients aged 18 to 80 years undergoing elective minimally invasive abdominal surgery under general anesthesia. Renal perfusion will be assessed perioperatively and postoperatively(postoperative 1. hour) using Doppler ultrasonography-derived Renal Resistive Index (RRI) and Near-Infrared Spectroscopy (NIRS)-derived regional renal oxygen saturation (rSO₂). Measurements will be performed at predefined perioperative time points and correlated with intraoperative variables, postoperative renal function, and the occurrence of acute kidney injury.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Renal Regional Oxygen Saturation Measured by NIRS
Time Frame: after endotracheal intubation, immediately before extubation, and 1 hour after extubation
Renal regional oxygen saturation (rSO₂) will be measured bilaterally using Near-Infrared Spectroscopy (NIRS). NIRS values will be recorded at predefined perioperative time points.
after endotracheal intubation, immediately before extubation, and 1 hour after extubation
Change in Renal Resistive Index
Time Frame: after endotracheal intubation, immediately before extubation, and 1 hour after extubation
Renal Resistive Index (RRI) measured by Doppler ultrasonography at predefined perioperative time points. RRI will be calculated from peak systolic velocity and end-diastolic velocity obtained from renal interlobar or arcuate arteries.
after endotracheal intubation, immediately before extubation, and 1 hour after extubation

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Relationship Between Renal Resistive Index and Renal Regional Oxygen Saturation
Time Frame: after endotracheal intubation, immediately before extubation, and 1 hour after extubation
The relationship between renal Doppler ultrasonography-derived Renal Resistive Index (RRI) and NIRS-derived renal regional oxygen saturation (rSO₂) will be evaluated for the right and left kidneys at predefined perioperative measurement time points.
after endotracheal intubation, immediately before extubation, and 1 hour after extubation

Collaborators and Investigators

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

Sponsor

Istanbul University - Cerrahpasa

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)

January 7, 2026

Primary Completion (Estimated)

January 7, 2027

Study Completion (Estimated)

January 7, 2027

Study Registration Dates

First Submitted

June 3, 2026

First Submitted That Met QC Criteria

June 3, 2026

First Posted (Actual)

June 9, 2026

Study Record Updates

Last Update Posted (Actual)

June 9, 2026

Last Update Submitted That Met QC Criteria

June 3, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CUC-RenalPerfusion-2026

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data (IPD) will not be shared because the study was not designed with a data-sharing plan and participant confidentiality will be protected in accordance with institutional and ethical requirements.

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.

Clinical Trials on Acute Kidney Injury

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Cameroon

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe