Low-flow Versus Minimal-flow Sevoflurane Anesthesia During 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.

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Key information

Conditions

Prostate Cancer Anesthesia Genital Diseases Genital Diseases, Male Genital Neoplasms, Male Male Urogenital Diseases Neoplasms Neoplasms by Site Prostatic Diseases Prostatic Neoplasms Respiratory Mechanics Urogenital Diseases Urogenital Neoplasms

Age range

18 year and older

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Common Anesthetic Management

Other

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.

Primary outcomes

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).

Secondary outcomes

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.
Oxygenation parameters

Time frame: Intraoperative period (T0-Text).

Peripheral oxygen saturation (SpO₂) and arterial oxygen partial pressure (PaO₂) measured to evaluate intraoperative oxygenation.
Inhalational anesthetic consumption

Time frame: Postextubation

Total sevoflurane consumption recorded from the anesthesia machine at the end of surgery.

Sponsors and collaborators

Lead sponsor

Ankara City Hospital Bilkent

Other

Registry information

Official study title

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

Important dates

Study start: 2026
Primary completion: 2026
Study completion: 2026
First posted: Mar 16, 2026
Registry last updated: Apr 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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