Low-flow Versus Minimal-flow Sevoflurane Anesthesia During Robot-assisted Laparoscopic Radical Prostatectomy

April 13, 2026 updated by: Betül Güven, Ankara City Hospital Bilkent

A Prospective Randomized Study Comparing Low-Flow (1 L/Min) and Minimal-Flow (0.5 L/Min) Sevoflurane Anesthesia in Patients Undergoing Robot-Assisted Laparoscopic Radical Prostatectomy

Study Synopsis This protocol is formatted for ClinicalTrials.gov-style registration and manuscript-facing documentation. It is based on the uploaded Turkish ethics protocol and keeps the original core design: comparison of low-flow and minimal-flow sevoflurane anesthesia in robot-assisted laparoscopic radical prostatectomy.

Background and Rationale Robot-assisted laparoscopic radical prostatectomy (RALRP) is increasingly preferred for localized prostate cancer because of lower blood loss, reduced transfusion requirements, shorter hospitalization, and lower complication rates compared with open surgery. However, RALRP requires carbon dioxide pneumoperitoneum and steep Trendelenburg positioning, both of which may adversely affect respiratory mechanics, gas exchange, and hemodynamic stability.

Low-flow and minimal-flow anesthesia may improve humidification and warming of inspired gases, reduce inhalational agent consumption, decrease environmental waste, and potentially lower overall cost. Despite these theoretical and practical advantages, evidence remains limited regarding the physiologic safety and performance of minimal-flow sevoflurane anesthesia during long robotic pelvic surgery performed under pneumoperitoneum and steep Trendelenburg positioning.

Accordingly, this randomized prospective trial will compare low-flow (1 L/min) and minimal-flow (0.5 L/min) sevoflurane anesthesia during RALRP with respect to respiratory parameters, arterial blood gas values, intraoperative oxygenation variables, anesthetic consumption, and selected postoperative biochemical markers.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
70

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria

  • Male patients aged 18 years or older.
  • ASA physical status I-II.
  • Scheduled for elective robot-assisted laparoscopic radical prostatectomy.
  • Provision of written informed consent. Exclusion Criteria
  • ASA physical status III-V.
  • Severe cardiac, respiratory, hepatic, or renal disease.
  • Mental status disorder or significant hearing impairment that prevents consent or communication.
  • Known anxiety, depression, or other psychiatric disorder judged to interfere with study participation.
  • Withdrawal of consent or investigator decision for safety reasons.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Supportive Care
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Low-flow sevoflurane arm
After tracheal intubation, fresh gas flow will be set at 1 L/min until MAC 1 is achieved. Thereafter, flow will be reduced to 0.5 L/min for maintenance.
Other: Common Anesthetic Management

Standard intraoperative monitoring including BIS, pulse oximetry, temperature, and anesthesia workstation-derived respiratory variables.

  • Arterial blood gas sampling after intubation, before pneumoperitoneum, after pneumoperitoneum/positioning, hourly during pneumoperitoneum, at the end of pneumoperitoneum in supine position, and before extubation.
  • Routine safety limits on the anesthesia machine: end-tidal carbon dioxide upper alarm 45 mmHg, inspired oxygen lower alarm 35%, inspired carbon dioxide upper alarm 3 mmHg.
  • Routine device self-test each morning and between patients.
  • Minimal dead space strategy with avoidance of unnecessary circuit extension.
  • Close monitoring of soda lime; replacement if inspired carbon dioxide reaches 3 mmHg even without obvious color change.
  • If clinically necessary because of blood gas deterioration, BIS changes, or any safety concern, fresh gas flow may be increased and the participant may be withdrawn from the protocol intervention.
Experimental: Minimal-flow sevoflurane anesthesia
Fresh gas flow 1 L/min after intubation until MAC 1 is achieved, then reduced to 0.5 L/min for maintenance anesthesia.
Other: Common Anesthetic Management

Standard intraoperative monitoring including BIS, pulse oximetry, temperature, and anesthesia workstation-derived respiratory variables.

  • Arterial blood gas sampling after intubation, before pneumoperitoneum, after pneumoperitoneum/positioning, hourly during pneumoperitoneum, at the end of pneumoperitoneum in supine position, and before extubation.
  • Routine safety limits on the anesthesia machine: end-tidal carbon dioxide upper alarm 45 mmHg, inspired oxygen lower alarm 35%, inspired carbon dioxide upper alarm 3 mmHg.
  • Routine device self-test each morning and between patients.
  • Minimal dead space strategy with avoidance of unnecessary circuit extension.
  • Close monitoring of soda lime; replacement if inspired carbon dioxide reaches 3 mmHg even without obvious color change.
  • If clinically necessary because of blood gas deterioration, BIS changes, or any safety concern, fresh gas flow may be increased and the participant may be withdrawn from the protocol intervention.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Arterial partial pressure of carbon dioxide (PaCO₂)
Time Frame: intraoperative period, from post-intubation to before extubation on the day of surgery

Comparison of arterial PaCO₂ values between the minimal-flow anesthesia group (0.5 L/min) and the low-flow anesthesia group (1 L/min) measured during robot-assisted laparoscopic radical prostatectomy.

Arterial blood gas analysis will be performed at predefined intraoperative time points (T0: post-intubation, T1: before pneumoperitoneum, T2: after pneumoperitoneum and positioning, hourly during pneumoperitoneum, at the end of pneumoperitoneum, and before extubation).
intraoperative period, from post-intubation to before extubation on the day of surgery

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
End-tidal carbon dioxide (EtCO₂)
Time Frame: intraoperatively
Comparison of end-tidal CO₂ levels between the minimal-flow and low-flow anesthesia groups during surgery.
intraoperatively
Oxygenation parameters
Time Frame: Intraoperative period (T0-Text).
Peripheral oxygen saturation (SpO₂) and arterial oxygen partial pressure (PaO₂) measured to evaluate intraoperative oxygenation.
Intraoperative period (T0-Text).
Inhalational anesthetic consumption
Time Frame: Postextubation
Total sevoflurane consumption recorded from the anesthesia machine at the end of surgery.
Postextubation

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Ankara City Hospital Bilkent

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 20, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 20, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 8, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 11, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 16, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 15, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 13, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • TABED1-26-2261

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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