Renal CalculiTA-fURSNCT01835600
Transient Apnea During Flexible Ureteroscopic Lithotripsy
A study testing Regular mechanical ventilation during flexible ureteroscopic lithotripsy, Small tidal-volume ventilation during flexible ureteroscopic lithotripsy and Transient apnea during flexible ureteroscopic lithotripsy in people with Renal Calculi and Kidney Stones, run by Chinese Medical Association at 1 site in China.
Trial 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… Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Renal Calculi, Kidney Stones
- What is being tested?
- Regular mechanical ventilation during flexible ureteroscopic lithotripsy, Small tidal-volume ventilation during flexible ureteroscopic lithotripsy and Transient apnea during flexible ureteroscopic lithotripsy
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 150 participants
- Where
- 1 siteChina
- Study dates
- 15 Jun 2020to 16 Apr 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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.
Who cannot join
- 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.
Show all 12Show fewer
- 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.
Trial locations and contacts
1 site in 1 country.
China1 site
Changhai Hospital, Naval Medical University
Shanghai, Shanghai Municipality, 200433
About this study
Official title: Transient Apnea to Stabilize Renal Motion During Flexible Ureteroscopic Lithotripsy: A Randomized Controlled Trial of Efficiency and Physiological Safety
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.
Read the detailed description
Respiration-related renal motion is a common technical challenge during flexible ureteroscopic laser lithotripsy. Movement of the kidney and collecting system may reduce laser targeting stability, interrupt continuous lithotripsy, and decrease active lithotripsy efficiency. Ventilation strategies that reduce respiratory motion may therefore improve operative stability, but they must be evaluated together with physiologic safety.
This study was designed as a single-center, prospective, three-arm, parallel-group randomized controlled trial. Adult patients scheduled for elective flexible ureteroscopic laser lithotripsy for renal stones under general anesthesia were screened for eligibility. After informed consent and eligibility confirmation, participants were randomized in a 1:1:1 ratio to one of three intraoperative ventilation strategies: regular mechanical ventilation, small tidal-volume ventilation, or transient apnea during active laser lithotripsy.
In the regular mechanical ventilation group, standard controlled ventilation was maintained during lithotripsy. In the small tidal-volume ventilation group, a reduced tidal-volume strategy was used during the lithotripsy phase to decrease respiration-related renal motion while maintaining clinically acceptable oxygenation and ventilation. In the transient apnea group, apnea was initiated during active laser lithotripsy after adequate preoxygenation and confirmation of hemodynamic stability by the anesthesiologist. Apnea was discontinued if any prespecified safety criterion occurred, including SpO₂ <90%, systolic blood pressure >160 mmHg or <80 mmHg, heart rate <50 beats/min, obvious arrhythmia, hemodynamic instability, or any safety concern from the attending anesthesiologist.
The primary efficacy outcome was active lithotripsy efficiency, defined as CT-based stone volume divided by active lithotripsy time. Secondary outcomes included active lithotripsy time, total operative time, postoperative stone-free status, residual stone burden, physiologic changes on arterial blood gas analysis, protocol-defined apnea interruption, and postoperative complications. Stone-free status was assessed by CT, and non-stone-free status was defined as any residual fragment >2 mm. Arterial blood gas measurements were obtained at baseline, 3 minutes, 6 minutes, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation.
- Conditions
- Renal Calculi, Kidney Stones
- Being tested
- Regular mechanical ventilation during flexible ureteroscopic lithotripsy, Small tidal-volume ventilation during flexible ureteroscopic lithotripsy, Transient apnea during flexible ureteroscopic lithotripsy
- Keywords
- Flexible ureteroscopy, Renal stone, Laser lithotripsy, Transient apnea, Renal motion, Lithotripsy efficiency, Mechanical ventilation, Small tidal-volume ventilation, Arterial blood gas
- Medical subject headings
- Kidney Calculi, Nephrolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Regular mechanical ventilation during flexible ureteroscopic lithotripsyOther
Standard controlled mechanical ventilation was maintained during the active lithotripsy phase according to routine anesthetic practice.
Small tidal-volume ventilation during flexible ureteroscopic lithotripsyOther
Controlled ventilation with a reduced tidal-volume strategy was applied during active lithotripsy under continuous anesthetic monitoring.
Transient apnea during flexible ureteroscopic lithotripsyOther
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.
| Study group | Role | What they receive |
|---|---|---|
| Regular Mechanical Ventilation | Active comparator | Participants received regular mechanical ventilation during flexible ureteroscopic laser lithotripsy under general anesthesia. Receives: 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. Receives: 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. Receives: Other: Transient apnea during flexible ureteroscopic lithotripsy |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: Intraoperative
Secondary outcomes (10)
Active lithotripsy time
Active lithotripsy time was defined as the duration of active laser fragmentation or dusting during flexible ureteroscopic lithotripsy.
Measured: Intraoperative
Total operative time
Total operative time was defined as the time from endoscope insertion to completion of the procedure.
Measured: Intraoperative
Stone-free status on postoperative day 1 CT
Stone-free status was assessed using CT on postoperative day 1. Non-stone-free status was defined as any residual fragment >2 mm.
Measured: Postoperative day 1
Arterial pH
Arterial pH was measured at baseline, 3 minutes, 6 minutes, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation.
Measured: Baseline to 3 minutes after resumption of ventilation
Arterial carbon dioxide tension
Arterial PaCO₂ was measured at baseline, 3 minutes, 6 minutes, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation.
Measured: Baseline to 3 minutes after resumption of ventilation
Arterial oxygen tension
Arterial PaO₂ was measured at baseline, 3 minutes, 6 minutes, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation.
Measured: Baseline to 3 minutes after resumption of ventilation
Arterial lactate
Arterial lactate was measured at baseline, 3 minutes, 6 minutes, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation.
Measured: Baseline to 3 minutes after resumption of ventilation
Base excess
Base excess was measured at baseline, 3 minutes, 6 minutes, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation.
Measured: Baseline to 3 minutes after resumption of ventilation
Protocol-defined interruption of transient apnea
Protocol-defined interruption was recorded when transient apnea was discontinued because of SpO₂ <90%, systolic blood pressure >160 mmHg or <80 mmHg, heart rate <50 beats/min, obvious arrhythmia, hemodynamic instability, or anesthesiologist concern.
Measured: Intraoperative
Postoperative complications
Postoperative complications were recorded and graded according to the Clavien-Dindo classification.
Measured: Up to 3 months after surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Apr 2013 (estimated)
- Study start15 Jun 2020
- Primary completion27 Dec 2024
- Study completion16 Apr 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Renal CalculiStudies 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 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.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 150 participants (actual)
Sponsor and investigators
- Lead sponsor
- Chinese Medical Association
- Sponsor type
- Research network
- Responsible party
- Principal investigator, Yi Zhou, Changhai Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01835600
- Sponsor's protocol ID
- SMV-312
- Acronym
- TA-fURS
- Status last verified
- Jun 2026
- First submitted
- 2 Apr 2013
- Last updated
- 15 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be publicly shared because the dataset contains patient-level perioperative, imaging, and physiologic monitoring data, and public sharing was not included in the original informed consent. Deidentified data underlying the published results may be made available from the corresponding investigator upon reasonable request and after institutional ethics approval.
Study at a glance
From the registry record, last updated by the sponsor on 15 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Transient Apnea to Stabilize Renal Motion During Flexible Ureteroscopic Lithotripsy: A Randomized Controlled Trial of Efficiency and Physiological Safety
- ClinicalTrials.gov ID
- NCT01835600
- Acronym / sponsor ID
- TA-fURS / SMV-312
- Conditions
- Renal Calculi, Kidney Stones
- Keywords
- Flexible ureteroscopy, Renal stone, Laser lithotripsy, Transient apnea, Renal motion, Lithotripsy efficiency, Mechanical ventilation, Small tidal-volume ventilation
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 150 participants (actual)
- Lead sponsor
- Chinese Medical AssociationResearch network
- Study start
- 15 Jun 2020 (actual)
- Primary completion
- 27 Dec 2024 (actual)
- Study completion
- 16 Apr 2025 (actual)
- First posted
- 19 Apr 2013 (estimated)
- 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.
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.
Detailed description
Respiration-related renal motion is a common technical challenge during flexible ureteroscopic laser lithotripsy. Movement of the kidney and collecting system may reduce laser targeting stability, interrupt continuous lithotripsy, and decrease active lithotripsy efficiency. Ventilation strategies that reduce respiratory motion may therefore improve operative stability, but they must be evaluated together with physiologic safety.
This study was designed as a single-center, prospective, three-arm, parallel-group randomized controlled trial. Adult patients scheduled for elective flexible ureteroscopic laser lithotripsy for renal stones under general anesthesia were screened for eligibility. After informed consent and eligibility confirmation, participants were randomized in a 1:1:1 ratio to one of three intraoperative ventilation strategies: regular mechanical ventilation, small tidal-volume ventilation, or transient apnea during active laser lithotripsy.
In the regular mechanical ventilation group, standard controlled ventilation was maintained during lithotripsy. In the small tidal-volume ventilation group, a reduced tidal-volume strategy was used during the lithotripsy phase to decrease respiration-related renal motion while maintaining clinically acceptable oxygenation and ventilation. In the transient apnea group, apnea was initiated during active laser lithotripsy after adequate preoxygenation and confirmation of hemodynamic stability by the anesthesiologist. Apnea was discontinued if any prespecified safety criterion occurred, including SpO₂ <90%, systolic blood pressure >160 mmHg or <80 mmHg, heart rate <50 beats/min, obvious arrhythmia, hemodynamic instability, or any safety concern from the attending anesthesiologist.
The primary efficacy outcome was active lithotripsy efficiency, defined as CT-based stone volume divided by active lithotripsy time. Secondary outcomes included active lithotripsy time, total operative time, postoperative stone-free status, residual stone burden, physiologic changes on arterial blood gas analysis, protocol-defined apnea interruption, and postoperative complications. Stone-free status was assessed by CT, and non-stone-free status was defined as any residual fragment >2 mm. Arterial blood gas measurements were obtained at baseline, 3 minutes, 6 minutes, and 9 minutes during the lithotripsy phase and 3 minutes after resumption of ventilation.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 3
- Model description
- 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.
| Arm | Type | Receives |
|---|---|---|
| Regular Mechanical Ventilation | Active comparator | Other: Regular mechanical ventilation during flexible ureteroscopic lithotripsyParticipants received regular mechanical ventilation during flexible ureteroscopic laser lithotripsy under general anesthesia. |
| Small Tidal-Volume Ventilation | Active comparator | Other: Small tidal-volume ventilation during flexible ureteroscopic lithotripsyParticipants 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. |
| Transient Apnea | Experimental | Other: Transient apnea during flexible ureteroscopic lithotripsyParticipants underwent transient apnea during active flexible ureteroscopic laser lithotripsy after adequate preoxygenation and confirmation of physiologic stability by the anesthesiologist. |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- 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.
Key exclusion criteria (12 listed)
- 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.
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 |
|---|---|---|
| Regular mechanical ventilation during flexible ureteroscopic lithotripsyStandard controlled mechanical ventilation was maintained during the active lithotripsy phase according to routine anesthetic practice. | Other | Regular Mechanical Ventilation |
| Small tidal-volume ventilation during flexible ureteroscopic lithotripsyControlled ventilation with a reduced tidal-volume strategy was applied during active lithotripsy under continuous anesthetic monitoring. | Other | Small Tidal-Volume Ventilation |
| Transient apnea during flexible ureteroscopic lithotripsyTransient 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. | Other | Transient Apnea |
Primary outcome
Active lithotripsy efficiency
Time frame: Intraoperative
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.
10 secondary outcomes
Active lithotripsy time
Time frame: Intraoperative
Total operative time
Time frame: Intraoperative
Stone-free status on postoperative day 1 CT
Time frame: Postoperative day 1
Arterial pH
Time frame: Baseline to 3 minutes after resumption of ventilation
Arterial carbon dioxide tension
Time frame: Baseline to 3 minutes after resumption of ventilation
Arterial oxygen tension
Time frame: Baseline to 3 minutes after resumption of ventilation
Arterial lactate
Time frame: Baseline to 3 minutes after resumption of ventilation
Base excess
Time frame: Baseline to 3 minutes after resumption of ventilation
Protocol-defined interruption of transient apnea
Time frame: Intraoperative
Postoperative complications
Time frame: Up to 3 months after surgery
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Jun 2026.
- Individual participant dataSharing planned: No. Individual participant data will not be publicly shared because the dataset contains patient-level perioperative, imaging, and physiologic monitoring data, and public sharing was not included in the original informed consent. Deidentified data underlying the published results may be made available from the corresponding investigator upon reasonable request and after institutional ethics approval.
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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. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Regular mechanical ventilation during flexible ureteroscopic lithotripsy, Small tidal-volume ventilation during flexible ureteroscopic lithotripsy and Transient apnea during flexible ureteroscopic lithotripsy in people with Renal Calculi and Kidney Stones, run by Chinese Medical Association at 1 site in China.
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 6 inclusion and 12 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: finished, as of the sponsor's last update on 15 Jun 2026. 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 China. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Active lithotripsy efficiency (time frame: Intraoperative). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 15 Jun 2026.