Effect of Tidal Volume on fURS Parameters (TIDAL-fURS)

Impact of Intraoperative Tidal Volume on Surgical Parameters During Flexible Ureteroscopy

The goal of this prospective clinical trial is to evaluate how intraoperative tidal volume settings affect surgical parameters and outcomes in adult patients undergoing flexible ureteroscopy (fURS) for kidney stones. The participant population includes patients over 18 years of age with unilateral, single renal stones located in the upper/middle calyx or renal pelvis.

This study aims to answer are:

Does intraoperative tidal volume influence operative time and surgical efficiency during fURS?

Does tidal volume affect laser energy use, lasing efficiency, stone-free rates, and complication rates (infection or bleeding)?

The investigators will compare two groups based on tidal volume recorded during anaesthesia:

Group 1: Low tidal volume (< 500 mL)

Group 2: Standard tidal volume (≥ 500 mL)

to determine whether tidal volume differences impact surgical performance and postoperative outcomes.

Participants will:

Undergo fURS performed under general anaesthesia with standard ASA monitoring, including ETCO₂ and TOF monitoring.

Have their respiratory parameters (tidal volume, peak airway pressure, PEEP, respiratory rate, ETCO₂) and surgical data (operative time, laser settings, fluoroscopy use, stone-free status) recorded during and after surgery.

Study Overview

• Status: Completed
• Conditions: Urolithiasis; Flexible Ureteroscopy; Tidal Volume
• Intervention / Treatment: Procedure: Flexible Ureteroscopy

• Study Type: Interventional
• Enrollment (Actual): 70
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Pendik
    • Istanbul, Pendik, Turkey (Türkiye), 34854
      • Marmara University School of Medicine Urology Department

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Age ≥18 years

Unilateral, single kidney stones located in the upper or middle calyx or in the renal pelvis

Exclusion Criteria:

Chronic obstructive pulmonary disease (COPD)

Pregnancy

History of abdominal, retroperitoneal, or thoracic surgery

Kidney anomalies

Stones located in the lower calyx

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Low Tidal Volume	Procedure: Flexible Ureteroscopy; Between October 2025 and December 2025, Patients who underwent fURS surgery in our clinic, with the surgical indication determined according to the EAU guidelines, were included in the study. Patients over 18 years of age with unilateral, single stones located in the upper or middle calyx or in the renal pelvis were included in the study. Patients with chronic obstructive pulmonary disease, pregnancy, a history of abdominal, retroperitoneal, or thoracic surgery, kidney anomalies, or stones located in the lower calyx were excluded.
Placebo Comparator: Normal Tidal Volume	Procedure: Flexible Ureteroscopy; Between October 2025 and December 2025, Patients who underwent fURS surgery in our clinic, with the surgical indication determined according to the EAU guidelines, were included in the study. Patients over 18 years of age with unilateral, single stones located in the upper or middle calyx or in the renal pelvis were included in the study. Patients with chronic obstructive pulmonary disease, pregnancy, a history of abdominal, retroperitoneal, or thoracic surgery, kidney anomalies, or stones located in the lower calyx were excluded.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation Between Intraoperative Respiratory Parameters and Surgical Outcomes	Respiratory parameter measured: Tidal Volume (mL/kg) Measurement tool: Anaesthesia ventilator/monitoring system Unit: milliliters per kilogram (mL/kg) Surgical outcomes assessed: Stone-free rate (%), assessed by postoperative non-contrast CT scan Operative time (minutes), recorded from surgical logs Complications, graded using the Clavien-Dindo classification The objective is to determine the statistical correlation between tidal volume and each of these surgical outcomes.	2 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation Between Intraoperative Respiratory Parameters and Seconder Outcomes	Operative time (minutes), recorded from surgical logs Surgical efficiency (stone volume / operative time, mm³/min) Laser time (seconds), recorded from laser console Laser energy used (Joules), recorded from laser console Lasing efficiency (stone volume / lasing time, mm³/sec) Complications, graded using the Clavien-Dindo classification Bleeding rate (%), incidence of significant intra- or postoperative bleeding Infection rate (%), incidence of postoperative urinary tract infection Length of hospital stay (days), total postoperative hospitalization	2 months

Collaborators and Investigators

• Sponsor: Tarik Emre Sener

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2025
• Primary Completion (Actual): November 23, 2025
• Study Completion (Actual): November 24, 2025

Study Registration Dates

• First Submitted: November 30, 2025
• First Submitted That Met QC Criteria: December 12, 2025
• First Posted (Actual): December 26, 2025

Study Record Updates

• Last Update Posted (Actual): December 26, 2025
• Last Update Submitted That Met QC Criteria: December 12, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urolithiasis
• Other Study ID Numbers: MAR.UAD.0026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

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