Transient Apnea During Flexible Ureteroscopic Lithotripsy

NCT01835600 | Completed

• 1 other identifier: SMV-312
• Study Type: interventional
• Target: 150
• Locations: 1 country
• Sites: 1

Brief Summary

Respiration-related renal motion may reduce targeting stability during flexible ureteroscopic laser lithotripsy and thereby decrease lithotripsy efficiency. This single-center, three-arm randomized controlled trial evaluated whether transient apnea during active lithotripsy could improve lithotripsy efficiency while maintaining short-term physiologic safety. A total of 150 patients undergoing flexible ureteroscopic lithotripsy for renal stones were randomized in a 1:1:1 ratio to regular mechanical ventilation, small tidal-volume ventilation, or transient apnea. The primary outcome was active lithotripsy efficiency, defined as CT-based stone volume divided by active lithotripsy time. Physiologic safety was assessed using serial arterial blood gas measurements at baseline, 3, 6, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation, together with continuous intraoperative cardiopulmonary monitoring.

Conditions

Renal Calculi; Kidney Stones

Keywords

Flexible ureteroscopy; Renal stone; Laser lithotripsy; Transient apnea; Renal motion; Lithotripsy efficiency; Mechanical ventilation; Small tidal-volume ventilation; Arterial blood gas

Outcome Measures

Primary Outcomes (1)

• Active lithotripsy efficiency

  Active lithotripsy efficiency was defined as CT-based stone volume divided by active lithotripsy time. Stone volume was calculated from stone length, width, and depth using the ellipsoid formula. Active lithotripsy time was defined as the duration of active laser fragmentation or dusting and excluded ureteral access, endoscopic inspection, stent placement, and other non-lithotripsy procedural time.

  Intraoperative

Secondary Outcomes (10)

• Active lithotripsy time

  Intraoperative

• Total operative time

  Intraoperative

• Stone-free status on postoperative day 1 CT

  Postoperative day 1

• Arterial pH

  Baseline to 3 minutes after resumption of ventilation

• Arterial carbon dioxide tension

  Baseline to 3 minutes after resumption of ventilation

Study Arms (3)

Regular Mechanical Ventilation

ACTIVE COMPARATOR

Participants received regular mechanical ventilation during flexible ureteroscopic laser lithotripsy under general anesthesia.

Other: Regular mechanical ventilation during flexible ureteroscopic lithotripsy

Small Tidal-Volume Ventilation

ACTIVE COMPARATOR

Participants received small tidal-volume controlled ventilation during active flexible ureteroscopic laser lithotripsy to reduce respiration-related renal motion while maintaining clinically acceptable oxygenation and ventilation.

Other: Small tidal-volume ventilation during flexible ureteroscopic lithotripsy

Transient Apnea

EXPERIMENTAL

Participants underwent transient apnea during active flexible ureteroscopic laser lithotripsy after adequate preoxygenation and confirmation of physiologic stability by the anesthesiologist.

Other: Transient apnea during flexible ureteroscopic lithotripsy

Interventions

Small tidal-volume ventilation during flexible ureteroscopic lithotripsy OTHER

Controlled ventilation with a reduced tidal-volume strategy was applied during active lithotripsy under continuous anesthetic monitoring.

Small Tidal-Volume Ventilation

Transient apnea during flexible ureteroscopic lithotripsy OTHER

Transient apnea was applied during active laser lithotripsy to reduce respiration-related renal motion. Apnea was initiated after adequate preoxygenation and confirmation of physiologic stability. Apnea was terminated if SpO₂ was \<90%, systolic blood pressure was \>160 mmHg or \<80 mmHg, heart rate was \<50 beats/min, obvious arrhythmia occurred, hemodynamic instability developed, or the attending anesthesiologist had any safety concern.

Transient Apnea

Regular mechanical ventilation during flexible ureteroscopic lithotripsy OTHER

Standard controlled mechanical ventilation was maintained during the active lithotripsy phase according to routine anesthetic practice.

Regular Mechanical Ventilation

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Age 18 to 80 years.
• Scheduled for elective flexible ureteroscopic laser lithotripsy for renal stones under general anesthesia.
• Preoperative CT confirming renal stones suitable for flexible ureteroscopic lithotripsy.
• Stone size ≥10 mm and \<20 mm.
• American Society of Anesthesiologists physical status I to III.
• Ability to provide written informed consent.

You may not qualify if:

• American Society of Anesthesiologists physical status IV or V.
• Stone size \<10 mm or ≥20 mm.
• Multiple renal stones requiring a combined or alternative surgical strategy.
• Radiolucent stone or inadequate radiographic assessment.
• Uncontrolled urinary tract infection.
• Reduced pulmonary function, including FEV1/FVC \<70%, or other clinically relevant pulmonary dysfunction judged unsuitable for transient apnea.
• Significant cardiopulmonary instability or anesthetic contraindication to transient apnea.
• Pregnancy or planned pregnancy during the study period.
• Planned combined procedure or alternative surgical strategy.
• Incomplete preoperative assessment.
• Declined participation after counselling.
• Withdrawal of consent before randomization.

Sponsors & Collaborators

• Chinese Medical Association: lead

Study Sites (1)

Changhai Hospital, Naval Medical University

Shanghai, Shanghai Municipality, 200433, China

Location

MeSH Terms

Conditions

Kidney Calculi; Nephrolithiasis

Condition Hierarchy (Ancestors)

Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Urolithiasis; Urinary Calculi; Male Urogenital Diseases; Calculi; Pathological Conditions, Anatomical; Pathological Conditions, Signs and Symptoms

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: The surgeon and anesthesiology team were not masked because the assigned ventilation strategy was apparent during the procedure. Postoperative CT images were assessed by outcome assessors who were not involved in the intraoperative ventilation protocol and were masked to group allocation whenever feasible.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: NETWORK
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator, Department of Anesthesiology

Model Details: Participants were randomized in a 1:1:1 ratio to regular mechanical ventilation, small tidal-volume ventilation, or transient apnea during flexible ureteroscopic laser lithotripsy.

Study Record Dates

• First Submitted: April 2, 2013
• First Posted: April 19, 2013
• Study Start: June 15, 2020
• Primary Completion: December 27, 2024
• Study Completion: April 16, 2025
• Last Updated: June 15, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will not share

Locations

CN (1)