Effects of Minimal and Metabolic Flow Sevoflurane Anesthesia in Gynecological Surgery Patients

NCT07465146 | Completed

• 2 other identifiers: KA 24/235Baskent University
• Study Type: observational
• Target: 97
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Low-flow Anesthesia

Outcome Measures

Primary Outcomes (5)

• Core body temperature (°C)

  Mean intraoperative core body temperature (Degrees Celsius (°C)): Measured intraoperatively using an esophageal temperature probe.

  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.

  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.

  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.

  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.

  At the end of surgery / immediate postoperative period

Secondary Outcomes (1)

• Anesthetic gas cost (USD or local currency)

  Intraoperative period - calculated at the end of surgery (1-2 hours).

Study Arms (2)

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.

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.

Procedure: Low Flow Anesthesia

Interventions

Low Flow Anesthesia PROCEDURE

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.

Also known as: Metabolic Flow (0.3 L/min), Minimal Flow (0.5 L/min)

Metabolic Flow Group (0.3 L/min); Minimal Flow Group (0.5 L/min)

Eligibility Criteria

• Age: 18 Years - 65 Years
• Gender Eligibility Details: Participant eligibility is limited to biologically female
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Probability Sample

Study Population

Adult female patients scheduled for elective gynecologic surgery under general anesthesia at Baskent University Ankara Hospital.

You may qualify if:

• Female patients aged 18-65 years
• Undergoing elective gynecologic surgery under general anesthesia (including hysterectomy and/or oophorectomy)

You may not qualify if:

• Pregnant patients
• Patients with advanced cardiac disease
• Patients with advanced renal disease
• Patients with advanced hepatic disease
• Patients with advanced respiratory disease
• Severe obesity
• 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

Sponsors & Collaborators

• Baskent University: lead

Study Sites (1)

Baskent University Ankara Hospital

Ankara, 06490, Turkey (Türkiye)

Location

Study Officials

• Asude Ayhan, MD

  Baskent University Ankara Hospital, Department of Anesthesiology and Reanimation

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 26, 2026
• First Posted: March 11, 2026
• Study Start: November 5, 2024
• Primary Completion: February 5, 2025
• Study Completion: February 5, 2025
• Last Updated: March 11, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)