The Effect of Continuous Low Tidal Volume Ventilation During Cardiopulmonary Bypass on Renal Resistive Index

Postoperative acute kidney injury following cardiopulmonary bypass surgery represents a significant barrier to patient recovery and is closely associated with increased postoperative morbidity and mortality. Studies have shown that the incidence of AKI aftercardiopulmonary bypass surgeryranges between 5% and 30%.

The Renal Resistive Index, measured by Doppler ultrasonography, is an increasingly utilized parameter that provides valuable insights into renal hemodynamics and vascular resistance. A normal RRI is typically below 0.70; elevated values may indicate increased renal vascular resistance or microvascular damage. Bossard et al. demonstrated that increased RRI in the early postoperative period is associated with the development of AKI. Early evaluation of renal blood flow thus facilitates prompt detection of AKI. Both preoperative and postoperative RRI measurements are considered useful tools for identifying early renal dysfunction. Monitoring RRI before and after CABG may provide critical information for preventing postoperative renal complications.

Study Overview

• Status: Completed
• Conditions: Postoperative Complications
• Intervention / Treatment: Other: Patients Undergoing Apneic Ventilation During CABG; Other: Patients Undergoing Low Tidal Volume Ventilation During CABG

Detailed Description

Postoperative acute kidney injury following cardiopulmonary bypass surgery represents a significant barrier to patient recovery and is closely associated with increased postoperative morbidity and mortality. Studies have shown that the incidence of AKI after CABG ranges between 5% and 30%.

The Renal Resistive Index, measured by Doppler ultrasonography, is an increasingly utilized parameter that provides valuable insights into renal hemodynamics and vascular resistance. A normal RRI is typically below 0.70; elevated values may indicate increased renal vascular resistance or microvascular damage. Bossard et al. demonstrated that increased RRI in the early postoperative period is associated with the development of AKI. Early evaluation of renal blood flow thus facilitates prompt detection of AKI. Both preoperative and postoperative RRI measurements are considered useful tools for identifying early renal dysfunction. Monitoring RRI before and after CABG may provide critical information for preventing postoperative renal complications.In recent years, significant advancements have been made in both surgical and anesthetic techniques in cardiac surgery. During CABG, the commonly used ventilation strategy during cardiopulmonary bypass is apneic ventilation. However, low tidal volume ventilation has been proposed as an alternative, with a growing body of literature supporting its use. LTV has been associated with reduced postoperative pulmonary complications, earlier extubation, and prevention of atelectasis and pulmonary edema.

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Konya, Turkey (Türkiye)
    • Konya City Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Study Population

In the Low Tidal Volume (LTV) Group, mechanical ventilation will be set to deliver tidal volumes of 3-4 mL/kg based on ideal body weight, with a respiratory rate of approximately 12 breaths per minute, ensuring a minute ventilation not exceeding 12 L/min. Positive end-expiratory pressure (PEEP) will be maintained between 5-8 cmH₂O, and the inspired oxygen fraction (FiO₂) will be set at 50%.

Description

Inclusion Criteria:

• Patients scheduled for elective cardiac bypass surgery
• Male and female patients over 18 years of age
• Patients with an American Society of Anesthesiologists (ASA) physical status classification of II, III, or IV

Exclusion Criteria:

• Chronic renal failure requiring dialysis
• Patients requiring emergency surgery

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Patients Undergoing Low Tidal Volume Ventilation During CABG; patients undergoing coronary artery bypass grafting receive continuous low tidal volume ventilation during cardiopulmonary bypass	Other: Patients Undergoing Low Tidal Volume Ventilation During CABG; Postoperative Evaluation of Renal Resistive Index Using Doppler Ultrasound After Cardiopulmonary Bypass
Active Comparator: Patients Managed With Apneic Ventilation During Cardiopulmonary Bypass"; patients undergoing coronary artery bypass grafting are managed with apnea ventilation during cardiopulmonary bypass	Other: Patients Undergoing Apneic Ventilation During CABG; Postoperative Evaluation of Renal Resistive Index Using Doppler Ultrasound After Cardiopulmonary Bypass"

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Renal resistive ındex	Measurement of Changes in Renal Resistive Index Associated With Low Tidal Volume and Apneic Ventilation	Postoperative 45 minutes

Collaborators and Investigators

• Sponsor: Konya City Hospital

Study record dates

Study Major Dates

• Study Start (Actual): July 15, 2025
• Primary Completion (Actual): December 1, 2025
• Study Completion (Actual): December 1, 2025

Study Registration Dates

• First Submitted: June 23, 2025
• First Submitted That Met QC Criteria: June 23, 2025
• First Posted (Actual): June 29, 2025

Study Record Updates

• Last Update Posted (Actual): February 4, 2026
• Last Update Submitted That Met QC Criteria: February 1, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pathologic Processes; Pathological Conditions, Signs and Symptoms; Postoperative Complications
• Other Study ID Numbers: bypass surgery

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No