Retrograde Intrarenal Surgery (RIRS)SEVOMIN-RIRSNCT07248917
Evaluation of Sevoflurane Consumption During Initial Phase of Minimal-Flow Anesthesia in Retrograde Intrarenal Surgery
A study testing Sevoflurane Anesthesia with Minimal-flow and Sevoflurane Anesthesia with Low-flow in people with Retrograde Intrarenal Surgery (RIRS) and Urolithiasis, run by Dr. Lutfi Kirdar Kartal Training and Research Hospital at 1 site in Turkey (Türkiye).
Trial summary
This study aimed to compare the effects of minimal-flow (0.5 L/min) and low-flow (1.0 L/min) sevoflurane anesthesia on agent consumption, anesthetic depth, and cardiorespiratory safety during retrograde intrarenal surgery (RIRS). Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Retrograde Intrarenal Surgery (RIRS), Urolithiasis, Minimal-flow Anesthesia
- What is being tested?
- Sevoflurane Anesthesia with Minimal-flow and Sevoflurane Anesthesia with Low-flow
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 62 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 1 Oct 2024to 1 Sep 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 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adults aged 18 to 65 years
- ASA (American Society of Anesthesiologists) Physical Status I or II
- Scheduled to undergo elective retrograde intrarenal surgery (RIRS) under general anesthesia
- Provided written informed consent
- Able to cooperate with preoperative evaluation procedures
Who cannot join
- ASA Physical Status III or higher
- History of respiratory disease (e.g., asthma, COPD, restrictive lung disease)
- Known hepatic or renal dysfunction
- Neurological or psychiatric disorders that may affect BIS monitoring or anesthetic response
- Known allergy or hypersensitivity to sevoflurane or other volatile anesthetics
- Pregnancy or breastfeeding
Show all 9Show fewer
- Obesity (BMI > 30 kg/m²)
- Anticipated difficult airway or history of intubation complications
- Participation in another clinical trial within the past 30 days
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Kartal Dr. Lütfi Kırdar City Hospital, University of Health Sciences
Istanbul, 34865
About this study
Official title: A Comparative Evaluation of Sevoflurane Consumption and Anesthetic Depth During the Initial Phase of Minimal-Flow Versus Low-Flow Anesthesia in Patients Undergoing Retrograde Intrarenal Surgery (RIRS)
This study aimed to compare the effects of minimal-flow (0.5 L/min) and low-flow (1.0 L/min) sevoflurane anesthesia on agent consumption, anesthetic depth, and cardiorespiratory safety during retrograde intrarenal surgery (RIRS). A total of 62 adult patients undergoing elective RIRS were enrolled in this single-center interventional trial. Patients were divided into two groups based on the fresh gas flow rate used during the maintenance phase of anesthesia. The primary outcome was total sevoflurane consumption at the end of anesthesia. Secondary outcomes included time to reach 1 minimum alveolar concentration (MAC), vaporizer shut-off time, BIS values, MAC levels, and respiratory parameters. The study found that minimal-flow anesthesia was as effective and safe as low-flow anesthesia, with lower agent consumption and no adverse effects on hemodynamic or respiratory parameters. These findings support the use of minimal-flow anesthesia for improved cost-efficiency and environmental sustainability.
Read the detailed description
This prospective, single-center, interventional study was designed to evaluate and compare the effects of minimal-flow and low-flow anesthesia on sevoflurane consumption, anesthetic depth, and respiratory parameters during retrograde intrarenal surgery (RIRS). After obtaining ethics committee approval (Decision No: 2024/16/925, Date: 17.09.2024), a total of 62 adult patients undergoing elective RIRS under general anesthesia were enrolled and divided into two groups based on the fresh gas flow rate used during the maintenance phase of anesthesia.
In Group 1 (Minimal-flow group), the fresh gas flow was reduced to 0.5 L/min after the initial 10 minutes of anesthesia. In Group 2 (Low-flow group), a 1.0 L/min flow rate was maintained. Both groups received the same induction and maintenance protocols with sevoflurane, and depth of anesthesia was monitored via BIS (Bispectral Index). Key variables measured included the total amount of sevoflurane consumed (mL), the time to reach 1 MAC, the vaporizer shut-off time, intraoperative BIS and MAC values, EtCO₂, and respiratory rate. Safety outcomes such as hemodynamic stability and desaturation were also recorded.
The primary outcome was total sevoflurane consumption. Secondary outcomes included anesthetic depth consistency (BIS/MAC), respiratory parameters, and time-based metrics. Statistical analysis revealed that minimal-flow anesthesia significantly reduced sevoflurane usage without compromising patient safety or anesthetic depth.
The results support the clinical use of minimal-flow anesthesia as a safe, cost-effective, and environmentally favorable alternative to low-flow techniques in selected urological procedures.
- Conditions
- Retrograde Intrarenal Surgery (RIRS), Urolithiasis, Minimal-flow Anesthesia, Sevoflurane, Anesthetic Consumption, Inhalational Anesthesia
- Being tested
- Sevoflurane Anesthesia with Minimal-flow, Sevoflurane Anesthesia with Low-flow
- Keywords
- minimal-flow anesthesia, low-flow anesthesia, sevoflurane, retrograde intrarenal surgery (RIRS), volatile consumption, environmental sustainability, MAC, BIS
- Medical subject headings
- Urolithiasis, Mycobacterium avium-intracellulare Infection
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Sevoflurane Anesthesia with Minimal-flowDrug
Patients received general anesthesia with sevoflurane. After induction, the fresh gas flow rate was reduced to 0.5 L/min during the maintenance phase of anesthesia for retrograde intrarenal surgery (RIRS). Agent consumption and anesthetic depth (via BIS and MAC) were monitored.
Sevoflurane Anesthesia with Low-flowDrug
Patients received general anesthesia with sevoflurane. A fresh gas flow rate of 1.0 L/min was maintained during the maintenance phase of anesthesia for retrograde intrarenal surgery (RIRS). BIS, MAC, and respiratory parameters were recorded.
| Study group | Role | What they receive |
|---|---|---|
| Minimal-flow Sevoflurane Group | Experimental | Participants in this group received general anesthesia using sevoflurane with a fresh gas flow rate reduced to 0.5 L/min after the initial 10 minutes of induction. Anesthesia depth was monitored using BIS, and agent consumption and respiratory parameters were recorded throughout the retrograde intrarenal surgery (RIRS) procedure. Receives: Drug: Sevoflurane Anesthesia with Minimal-flow |
| Low-flow Sevoflurane Group | Active comparator | Participants in this group received general anesthesia using sevoflurane with a consistent 1.0 L/min fresh gas flow during the maintenance phase. BIS monitoring, agent consumption, and respiratory parameters were recorded throughout the retrograde intrarenal surgery (RIRS). Receives: Drug: Sevoflurane Anesthesia with Low-flow |
What is being measured
The primary outcome is the main question the study is designed to answer.
Total Sevoflurane Consumption (mL)
Total volume of sevoflurane (in milliliters) used during the maintenance phase of general anesthesia, calculated automatically by the anesthesia machine and recorded at the end of surgery.
Measured: End of surgery (approximately 60-90 minutes after anesthesia induction)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Nov 2025
- Study start1 Oct 2024
- Primary completion1 Jun 2025
- Study completion1 Sep 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Retrograde Intrarenal Surgery (RIRS)Studies 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
- This was a prospective, two-arm, parallel-group study in which patients undergoing retrograde intrarenal surgery (RIRS) were randomly assigned to receive either minimal-flow (0.5 L/min) or low-flow (1.0 L/min) sevoflurane anesthesia. Participants were allocated to one group only and followed independently throughout the procedure. No crossover between groups occurred. The study aimed to compare anesthetic consumption, depth of anesthesia, and cardiorespiratory safety between the two anesthetic flow techniques.
- Masking
- None (open label)
- Enrolment
- 62 participants (actual)
Sponsor and investigators
- Lead sponsor
- Dr. Lutfi Kirdar Kartal Training and Research Hospital
- Sponsor type
- Other government
- Responsible party
- Principal investigator, Umit Yildiz, Dr. Lutfi Kirdar Kartal Training and Research Hospital
- Investigators
- UMIT YILDIZ, M.D., Principal investigator, Department of Anesthesiology and Reanimation, Kartal Dr. Lütfi Kırdar City Hospital, University of Health Sciences, Istanbul, Turkey
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07248917
- Sponsor's protocol ID
- KLKSH-ANES-SEVOMIN-RIRS-001
- Other IDs
- 2024/16/925
- Acronym
- SEVOMIN-RIRS
- Status last verified
- Nov 2025
- First submitted
- 18 Nov 2025
- Last updated
- 25 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Our study is: Single-center Non-commercial Conducted as part of a medical specialty thesis There is no stated plan to share anonymized individual-level data beyond what is reported in our thesis or publication
Study at a glance
From the registry record, last updated by the sponsor on 25 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Comparative Evaluation of Sevoflurane Consumption and Anesthetic Depth During the Initial Phase of Minimal-Flow Versus Low-Flow Anesthesia in Patients Undergoing Retrograde Intrarenal Surgery (RIRS)
- ClinicalTrials.gov ID
- NCT07248917
- Acronym / sponsor ID
- SEVOMIN-RIRS / KLKSH-ANES-SEVOMIN-RIRS-001
- Conditions
- Retrograde Intrarenal Surgery (RIRS), Urolithiasis, Minimal-flow Anesthesia, Sevoflurane, Anesthetic Consumption, Inhalational Anesthesia
- Keywords
- minimal-flow anesthesia, low-flow anesthesia, sevoflurane, retrograde intrarenal surgery (RIRS), volatile consumption, environmental sustainability, MAC, BIS
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 62 participants (actual)
- Lead sponsor
- Dr. Lutfi Kirdar Kartal Training and Research HospitalOther government
- Study start
- 1 Oct 2024 (actual)
- Primary completion
- 1 Jun 2025 (actual)
- Study completion
- 1 Sep 2025 (actual)
- First posted
- 25 Nov 2025 (actual)
- 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.
This study aimed to compare the effects of minimal-flow (0.5 L/min) and low-flow (1.0 L/min) sevoflurane anesthesia on agent consumption, anesthetic depth, and cardiorespiratory safety during retrograde intrarenal surgery (RIRS). A total of 62 adult patients undergoing elective RIRS were enrolled in this single-center interventional trial. Patients were divided into two groups based on the fresh gas flow rate used during the maintenance phase of anesthesia. The primary outcome was total sevoflurane consumption at the end of anesthesia. Secondary outcomes included time to reach 1 minimum alveolar concentration (MAC), vaporizer shut-off time, BIS values, MAC levels, and respiratory parameters. The study found that minimal-flow anesthesia was as effective and safe as low-flow anesthesia, with lower agent consumption and no adverse effects on hemodynamic or respiratory parameters. These findings support the use of minimal-flow anesthesia for improved cost-efficiency and environmental sustainability.
Detailed description
This prospective, single-center, interventional study was designed to evaluate and compare the effects of minimal-flow and low-flow anesthesia on sevoflurane consumption, anesthetic depth, and respiratory parameters during retrograde intrarenal surgery (RIRS). After obtaining ethics committee approval (Decision No: 2024/16/925, Date: 17.09.2024), a total of 62 adult patients undergoing elective RIRS under general anesthesia were enrolled and divided into two groups based on the fresh gas flow rate used during the maintenance phase of anesthesia.
In Group 1 (Minimal-flow group), the fresh gas flow was reduced to 0.5 L/min after the initial 10 minutes of anesthesia. In Group 2 (Low-flow group), a 1.0 L/min flow rate was maintained. Both groups received the same induction and maintenance protocols with sevoflurane, and depth of anesthesia was monitored via BIS (Bispectral Index). Key variables measured included the total amount of sevoflurane consumed (mL), the time to reach 1 MAC, the vaporizer shut-off time, intraoperative BIS and MAC values, EtCO₂, and respiratory rate. Safety outcomes such as hemodynamic stability and desaturation were also recorded.
The primary outcome was total sevoflurane consumption. Secondary outcomes included anesthetic depth consistency (BIS/MAC), respiratory parameters, and time-based metrics. Statistical analysis revealed that minimal-flow anesthesia significantly reduced sevoflurane usage without compromising patient safety or anesthetic depth.
The results support the clinical use of minimal-flow anesthesia as a safe, cost-effective, and environmentally favorable alternative to low-flow techniques in selected urological procedures.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- This was a prospective, two-arm, parallel-group study in which patients undergoing retrograde intrarenal surgery (RIRS) were randomly assigned to receive either minimal-flow (0.5 L/min) or low-flow (1.0 L/min) sevoflurane anesthesia. Participants were allocated to one group only and followed independently throughout the procedure. No crossover between groups occurred. The study aimed to compare anesthetic consumption, depth of anesthesia, and cardiorespiratory safety between the two anesthetic flow techniques.
| Arm | Type | Receives |
|---|---|---|
| Minimal-flow Sevoflurane Group | Experimental | Drug: Sevoflurane Anesthesia with Minimal-flowParticipants in this group received general anesthesia using sevoflurane with a fresh gas flow rate reduced to 0.5 L/min after the initial 10 minutes of induction. Anesthesia depth was monitored using BIS, and agent consumption and respiratory parameters were recorded throughout the retrograde intrarenal surgery (RIRS) procedure. |
| Low-flow Sevoflurane Group | Active comparator | Drug: Sevoflurane Anesthesia with Low-flowParticipants in this group received general anesthesia using sevoflurane with a consistent 1.0 L/min fresh gas flow during the maintenance phase. BIS monitoring, agent consumption, and respiratory parameters were recorded throughout the retrograde intrarenal surgery (RIRS). |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Adults aged 18 to 65 years
- ASA (American Society of Anesthesiologists) Physical Status I or II
- Scheduled to undergo elective retrograde intrarenal surgery (RIRS) under general anesthesia
- Provided written informed consent
- Able to cooperate with preoperative evaluation procedures
Key exclusion criteria (9 listed)
- ASA Physical Status III or higher
- History of respiratory disease (e.g., asthma, COPD, restrictive lung disease)
- Known hepatic or renal dysfunction
- Neurological or psychiatric disorders that may affect BIS monitoring or anesthetic response
- Known allergy or hypersensitivity to sevoflurane or other volatile anesthetics
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 |
|---|---|---|
| Sevoflurane Anesthesia with Minimal-flowPatients received general anesthesia with sevoflurane. After induction, the fresh gas flow rate was reduced to 0.5 L/min during the maintenance phase of anesthesia for retrograde intrarenal surgery (RIRS). Agent consumption and anesthetic depth (via BIS and MAC) were monitored. | Drug | Minimal-flow Sevoflurane Group |
| Sevoflurane Anesthesia with Low-flowPatients received general anesthesia with sevoflurane. A fresh gas flow rate of 1.0 L/min was maintained during the maintenance phase of anesthesia for retrograde intrarenal surgery (RIRS). BIS, MAC, and respiratory parameters were recorded. | Drug | Low-flow Sevoflurane Group |
Primary outcome
Total Sevoflurane Consumption (mL)
Time frame: End of surgery (approximately 60-90 minutes after anesthesia induction)
Total volume of sevoflurane (in milliliters) used during the maintenance phase of general anesthesia, calculated automatically by the anesthesia machine and recorded at the end of 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 25 Nov 2025.
- Individual participant dataSharing planned: No. Our study is: Single-center Non-commercial Conducted as part of a medical specialty thesis There is no stated plan to share anonymized individual-level data beyond what is reported in our thesis or publication
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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.
UMIT YILDIZ, M.D. principal investigator
Department of Anesthesiology and Reanimation, Kartal Dr. Lütfi Kırdar City Hospital, University of Health Sciences, Istanbul, Turkey
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Sevoflurane Anesthesia with Minimal-flow and Sevoflurane Anesthesia with Low-flow in people with Retrograde Intrarenal Surgery (RIRS) and Urolithiasis, run by Dr. Lutfi Kirdar Kartal Training and Research Hospital at 1 site in Turkey (Türkiye).
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 5 inclusion and 9 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 25 Nov 2025. 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 Turkey (Türkiye). 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?
Total Sevoflurane Consumption (mL) (time frame: End of surgery (approximately 60-90 minutes after anesthesia induction)). 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 25 Nov 2025.