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

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

70

Phase

  • 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

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
Intervention / Treatment
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

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

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

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)

March 20, 2026

Primary Completion (Estimated)

April 20, 2026

Study Completion (Estimated)

August 31, 2026

Study Registration Dates

First Submitted

March 8, 2026

First Submitted That Met QC Criteria

March 11, 2026

First Posted (Actual)

March 16, 2026

Study Record Updates

Last Update Posted (Actual)

April 15, 2026

Last Update Submitted That Met QC Criteria

April 13, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID 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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