Low-flow AnesthesiaNCT07465146
Effects of Minimal and Metabolic Flow Sevoflurane Anesthesia in Gynecological Surgery Patients
An observational study of Low-flow Anesthesia, run by Baskent University at 1 site in Turkey (Türkiye).
Trial summary
The aim of this study is to observe the effects of minimal and metabolically required basal anesthetic gas flow rates delivered by the anesthesia workstation under general anesthesia on body temperature, blood pressure, and heart rate during surgery. Read more about this study
- Who is it for?
- Ages 18 to 65 years, women only
- Conditions the study is for
- Low-flow Anesthesia
- What is being tested?
- Low Flow Anesthesia
- Type of treatment
- Surgery or procedure
- How many people
- 97 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 5 Nov 2024to 5 Feb 2025
- Phase
- Observational
- 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
- Women only
- No healthy volunteers
- Adult, Older adult
Study population: Adult female patients scheduled for elective gynecologic surgery under general anesthesia at Baskent University Ankara Hospital.
Who may be able to join
- Female patients aged 18-65 years
- Undergoing elective gynecologic surgery under general anesthesia (including hysterectomy and/or oophorectomy)
Who cannot join
- Pregnant patients
- Patients with advanced cardiac disease
- Patients with advanced renal disease
- Patients with advanced hepatic disease
- Patients with advanced respiratory disease
- Severe obesity
Show all 11Show fewer
- Heavy smokers
- Excessive alcohol consumption
- Known allergic sensitivity to halogenated anesthetic gases
- Use of medications that may interact with volatile anesthetics
- History of or susceptibility to malignant hyperthermia or neuromuscular disorders
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Baskent University Ankara Hospital
Ankara, 06490
About this study
Official title: Comparative Analysis of Sevoflurane-Based Minimal and Metabolic Flow Anaesthesia: A Prospective Randomized Study in a Gynecological Surgery Patient Cohort
The aim of this study is to observe the effects of minimal and metabolically required basal anesthetic gas flow rates delivered by the anesthesia workstation under general anesthesia on body temperature, blood pressure, and heart rate during surgery.
It also aims to evaluate the impact of reducing excessive delivery of anesthetic gases, air, and oxygen beyond the patient's physiological needs during general anesthesia on minimizing the harmful effects of anesthetic gases on the environment, climate, and global warming, as well as on contributing positively to hospital costs.
Read the detailed description
This prospective randomized study will be conducted in adult female patients undergoing elective gynecological surgery under general anesthesia. Following standard intravenous induction and endotracheal intubation, anesthesia will be maintained with sevoflurane using an advanced anesthesia workstation capable of delivering minimal and metabolic fresh gas flow rates.
After achieving the target anesthetic depth guided by minimum alveolar concentration (MAC) and MAC Brain monitoring, patients will be randomized to receive either minimal-flow (0.5 L/min) or metabolic-flow (0.3 L/min) fresh gas anesthesia. Randomization will be performed using an internet-based randomization tool.
Standard intraoperative monitoring will be applied in all patients, including electrocardiography, non-invasive blood pressure monitoring, pulse oximetry, capnography, anesthetic gas analysis, and esophageal temperature monitoring. Hemodynamic and respiratory parameters will be recorded at predefined time intervals throughout surgery. Sevoflurane consumption will be automatically calculated by the anesthesia workstation.
At the end of surgery, fresh gas flow will be increased to eliminate residual anesthetic gases, and patients will be extubated according to standard clinical criteria. Postoperative monitoring will continue in the post-anesthesia care unit.
The total study duration for each participant includes the intraoperative period and approximately 30 minutes of postoperative monitoring.
- Conditions
- Low-flow Anesthesia
- Being tested
- Low Flow Anesthesia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Low Flow AnesthesiaProcedure or surgery
Also called Metabolic Flow (0.3 L/min), Minimal Flow (0.5 L/min)
Adjustment of fresh gas flow rates during general anesthesia using a modern anesthesia workstation (Getinge Flow-C). Patients will be randomized to receive anesthesia with either minimal flow (0.5 L/min) or metabolic flow (0.3 L/min). All other anesthetic agents and monitoring parameters will remain standardized according to institutional protocols.
| Study group | Role | What they receive |
|---|---|---|
| Minimal Flow Group (0.5 L/min) | Participants will receive general anesthesia maintained with sevoflurane at a fresh gas flow rate of 0.5 L/min (minimal flow) after induction and achievement of target anesthetic concentration. Standard monitoring will be applied throughout surgery, including hemodynamic and respiratory parameters. Receives: Procedure: Low Flow Anesthesia | |
| Metabolic Flow Group (0.3 L/min) | Participants will receive general anesthesia maintained with sevoflurane at a fresh gas flow rate of 0.3 L/min (metabolic flow) after induction and achievement of target anesthetic concentration. Standard intraoperative monitoring will be applied as in the minimal flow group. Receives: Procedure: Low Flow Anesthesia |
What is being measured
The primary outcome is the main question the study is designed to answer.
Core body temperature (°C)
Mean intraoperative core body temperature (Degrees Celsius (°C)):
Measured intraoperatively using an esophageal temperature probe.
Measured: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Mean intraoperative heart rate (bpm)
Mean intraoperative heart rate (Beats per minute (bpm)): Measured intraoperatively via electrocardiographic monitoring.
Measured: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Mean intraoperative mean arterial pressure (mmHg)
Mean intraoperative mean arterial pressure (Millimeters of mercury (mmHg)): Measured intraoperatively using non-invasive blood pressure monitoring.
Measured: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Anesthetic gas consumption (mL)
Total sevoflurane consumption (Milliliters (mL)): As recorded by the anesthesia workstation.
Measured: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Richmond Agitation-Sedation Scale (RASS) (-5 to 4)
Richmond Agitation-Sedation Scale (RASS) (-5 to 4): The RASS is a 10-point scale ranging from -5 to +4. Negative scores (-1 to -5) indicate increasing levels of sedation, with -5 indicating an unarousable patient. Positive scores (+1 to +4) indicate increasing levels of agitation, with +4 indicating combative behavior. Scores closer to 0 reflect better recovery quality.
Measured: At the end of surgery / immediate postoperative period
Secondary outcomes (1)
Anesthetic gas cost (USD or local currency)
Total intraoperative anesthetic gas cost (USD or local currency):
Calculated based on total sevoflurane consumption recorded by the anesthesia workstation.
Measured: Intraoperative period - calculated at the end of surgery (1-2 hours).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted11 Mar 2026
- Study start5 Nov 2024
- Primary completion5 Feb 2025
- Study completion5 Feb 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Low-flow AnesthesiaStudies 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 97 participants (actual)
Sponsor and investigators
- Lead sponsor
- Baskent University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Asude Ayhan, MD, Principal investigator, Baskent University Ankara Hospital, Department of Anesthesiology and Reanimation
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07465146
- Sponsor's protocol ID
- KA 24/235
- Other IDs
- Baskent University
- Status last verified
- Mar 2026
- First submitted
- 26 Feb 2026
- Last updated
- 11 Mar 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 shared. Only summarized results will be published in scientific journals or presented at conferences.
Study at a glance
From the registry record, last updated by the sponsor on 11 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparative Analysis of Sevoflurane-Based Minimal and Metabolic Flow Anaesthesia: A Prospective Randomized Study in a Gynecological Surgery Patient Cohort
- ClinicalTrials.gov ID
- NCT07465146
- Acronym / sponsor ID
- KA 24/235
- Conditions
- Low-flow Anesthesia
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 97 participants (actual)
- Lead sponsor
- Baskent UniversityUniversity, hospital or other
- Study start
- 5 Nov 2024 (actual)
- Primary completion
- 5 Feb 2025 (actual)
- Study completion
- 5 Feb 2025 (actual)
- First posted
- 11 Mar 2026 (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.
The aim of this study is to observe the effects of minimal and metabolically required basal anesthetic gas flow rates delivered by the anesthesia workstation under general anesthesia on body temperature, blood pressure, and heart rate during surgery.
It also aims to evaluate the impact of reducing excessive delivery of anesthetic gases, air, and oxygen beyond the patient's physiological needs during general anesthesia on minimizing the harmful effects of anesthetic gases on the environment, climate, and global warming, as well as on contributing positively to hospital costs.
Detailed description
This prospective randomized study will be conducted in adult female patients undergoing elective gynecological surgery under general anesthesia. Following standard intravenous induction and endotracheal intubation, anesthesia will be maintained with sevoflurane using an advanced anesthesia workstation capable of delivering minimal and metabolic fresh gas flow rates.
After achieving the target anesthetic depth guided by minimum alveolar concentration (MAC) and MAC Brain monitoring, patients will be randomized to receive either minimal-flow (0.5 L/min) or metabolic-flow (0.3 L/min) fresh gas anesthesia. Randomization will be performed using an internet-based randomization tool.
Standard intraoperative monitoring will be applied in all patients, including electrocardiography, non-invasive blood pressure monitoring, pulse oximetry, capnography, anesthetic gas analysis, and esophageal temperature monitoring. Hemodynamic and respiratory parameters will be recorded at predefined time intervals throughout surgery. Sevoflurane consumption will be automatically calculated by the anesthesia workstation.
At the end of surgery, fresh gas flow will be increased to eliminate residual anesthetic gases, and patients will be extubated according to standard clinical criteria. Postoperative monitoring will continue in the post-anesthesia care unit.
The total study duration for each participant includes the intraoperative period and approximately 30 minutes of postoperative monitoring.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Minimal Flow Group (0.5 L/min) | – | Procedure: Low Flow AnesthesiaParticipants will receive general anesthesia maintained with sevoflurane at a fresh gas flow rate of 0.5 L/min (minimal flow) after induction and achievement of target anesthetic concentration. Standard monitoring will be applied throughout surgery, including hemodynamic and respiratory parameters. |
| Metabolic Flow Group (0.3 L/min) | – | Procedure: Low Flow AnesthesiaParticipants will receive general anesthesia maintained with sevoflurane at a fresh gas flow rate of 0.3 L/min (metabolic flow) after induction and achievement of target anesthetic concentration. Standard intraoperative monitoring will be applied as in the minimal flow group. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Adult female patients scheduled for elective gynecologic surgery under general anesthesia at Baskent University Ankara Hospital.
Key inclusion criteria (2 listed)
- Female patients aged 18-65 years
- Undergoing elective gynecologic surgery under general anesthesia (including hysterectomy and/or oophorectomy)
Key exclusion criteria (11 listed)
- Pregnant patients
- Patients with advanced cardiac disease
- Patients with advanced renal disease
- Patients with advanced hepatic disease
- Patients with advanced respiratory disease
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 |
|---|---|---|
| Low Flow AnesthesiaAlso: Metabolic Flow (0.3 L/min), Minimal Flow (0.5 L/min)Adjustment of fresh gas flow rates during general anesthesia using a modern anesthesia workstation (Getinge Flow-C). Patients will be randomized to receive anesthesia with either minimal flow (0.5 L/min) or metabolic flow (0.3 L/min). All other anesthetic agents and monitoring parameters will remain standardized according to institutional protocols. | Procedure or surgery | Metabolic Flow Group (0.3 L/min), Minimal Flow Group (0.5 L/min) |
Primary outcome
Core body temperature (°C)
Time frame: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Mean intraoperative core body temperature (Degrees Celsius (°C)): Measured intraoperatively using an esophageal temperature probe.
Mean intraoperative heart rate (bpm)
Time frame: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Mean intraoperative heart rate (Beats per minute (bpm)): Measured intraoperatively via electrocardiographic monitoring.
Mean intraoperative mean arterial pressure (mmHg)
Time frame: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Mean intraoperative mean arterial pressure (Millimeters of mercury (mmHg)): Measured intraoperatively using non-invasive blood pressure monitoring.
Anesthetic gas consumption (mL)
Time frame: From induction of anesthesia until the end of surgery (approximately 1-2 hours)
Total sevoflurane consumption (Milliliters (mL)): As recorded by the anesthesia workstation.
Richmond Agitation-Sedation Scale (RASS) (-5 to 4)
Time frame: At the end of surgery / immediate postoperative period
Richmond Agitation-Sedation Scale (RASS) (-5 to 4): The RASS is a 10-point scale ranging from -5 to +4. Negative scores (-1 to -5) indicate increasing levels of sedation, with -5 indicating an unarousable patient. Positive scores (+1 to +4) indicate increasing levels of agitation, with +4 indicating combative behavior. Scores closer to 0 reflect better recovery quality.
1 secondary outcome
Anesthetic gas cost (USD or local currency)
Time frame: Intraoperative period - calculated at the end of surgery (1-2 hours).
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 11 Mar 2026.
- Individual participant dataSharing planned: No. Individual participant data will not be shared. Only summarized results will be published in scientific journals or presented at conferences.
Related trials for Low-flow Anesthesia
Active, not recruitingObservational study
Post-Induction Low Cardiac Output Syndrome in Coronary Artery Bypass Graft Surgery
Cardiac Output, Low, Coronary Arterial Disease
RecruitingObservational study
Predictive Value of ONSD and NIRS for PDPH
Post-Dural Puncture Headache, Spinal Anesthetics Causing Adverse Effects in Therapeutic Use
Recruiting
Erector Spinae Plane Block and Low-Flow Anaesthesia in Laparoscopic Cholecystectomy
Postoperative Pain, Laparoscopic Cholecystectomy
RecruitingObservational study
Ultrasound for Postop Lung Issues in Low-Flow Anesthesia
Atelectasis, Postoperative, Cholecystitis; Gallstone
Not yet recruitingObservational study
Assessment of Sevoflurane Consumption During General Anesthesia With a Low Fresh Gas Flow Rate of 0.3 L/Min
Anesthesia
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.
Asude Ayhan, MD principal investigator
Baskent University Ankara Hospital, Department of Anesthesiology and Reanimation
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Low-flow Anesthesia, run by Baskent University 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 2 inclusion and 11 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 11 Mar 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 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?
Core body temperature (°C) (time frame: From induction of anesthesia until the end of surgery (approximately 1-2 hours)). The study lists 5 primary outcomes in all. 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 11 Mar 2026.