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NCT Number: NCT07313969

Ultra-Low-Flow Anesthesia and Carbon Footprint

This is a prospective, randomized controlled clinical trial evaluating the effects of ultra-low fresh gas flow (0.5 L/min) versus normal fresh gas flow (2.0 L/min) sevoflurane anesthesia in adult patients undergoing on-pump cardiac surgery. The study aims to determine whether ultra-low-flow anesthesia can be used safely to reduce volatile anesthetic consumption and environmental emissions without compromising hemodynamic stability or anesthetic depth.

Eligible adult patients scheduled for elective coronary artery bypass grafting (CABG) or valve surgery under general anesthesia will be randomized in a 1:1 ratio to one of two groups: ultra-low-flow (0.5 L/min) or normal-flow (2.0 L/min). All other anesthetic techniques, including induction drugs, ventilation parameters, temperature management, and perfusion strategies, will be standardized.

The primary outcome is the total amount of sevoflurane consumed per case. Secondary outcomes include intraoperative hemodynamic parameters (heart rate, mean arterial pressure), depth of anesthesia (BIS/MAC values), postoperative recovery times, and estimated carbon dioxide equivalent (CO₂e) emissions.

Outcome assessors and data analysts will remain blinded to group allocation. The findings of this study are expected to provide new evidence regarding the safety, efficiency, and environmental benefits of ultra-low-flow anesthesia techniques in cardiac surgery.

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Key information

Conditions

Low Flow Anesthesia Cardiac Surgery Sevoflurane Anesthesia

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Etlik City Hospital

Ankara, 06810, Turkey (Türkiye)

About this study

This randomized controlled trial investigates the impact of ultra-low-flow (0.5 L/min) versus normal-flow (2.0 L/min) sevoflurane anesthesia on anesthetic consumption, intraoperative hemodynamics, and environmental footprint during on-pump cardiac surgery. Although low-flow anesthesia is known to reduce anesthetic agent use and greenhouse gas emissions, evidence regarding its safety and efficiency during cardiopulmonary bypass procedures remains limited.

Adult patients scheduled for elective CABG or valve surgery will be randomly assigned to either an ultra-low-flow or normal-flow group. Randomization will be performed using a computer-generated sequence with variable block sizes and allocation concealment via sequentially numbered, opaque, sealed envelopes. All participants will receive standardized induction, perfusion, and maintenance techniques according to institutional cardiac anesthesia protocols.

The primary outcome measure is total sevoflurane consumption per patient, assessed through vaporizer readings and anesthetic gas analyzer data. Secondary outcomes include intraoperative mean arterial pressure, heart rate, BIS/MAC values, body temperature, recovery characteristics, and calculated CO₂ equivalent emissions. Outcome assessors and data analysts will remain blinded to group allocation.

This study is designed to evaluate both clinical and ecological aspects of anesthetic practice. It aims to determine whether ultra-low-flow anesthesia can provide equivalent anesthetic quality while offering substantial reductions in agent consumption and environmental impact. The findings may contribute to establishing safer and more sustainable anesthesia standards for cardiac surgery.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Adult patients aged 18-80 years
  • Scheduled for elective on-pump CABG or valve surgery
  • ASA physical status II-III
  • Written informed consent obtained

Exclusion criteria

  • Emergency surgery
  • Severe hepatic or renal dysfunction
  • Known allergy to volatile anesthetics
  • Significant pulmonary disease (e.g., COPD with GOLD III-IV)

Treatment and study plan

ultra low flow anesthesia

Drug

General anesthesia will be maintained with sevoflurane at a fresh gas flow rate of 0.5 L/min using oxygen and air mixture. The flow rate will be kept constant from post-induction stabilization until the end of cardiopulmonary bypass.

normal flow anesthesia

Drug

General anesthesia will be maintained with sevoflurane at a fresh gas flow rate of 2.0 L/min using oxygen and air mixture. The flow rate will be kept constant from post-induction stabilization until the end of cardiopulmonary bypass.

Primary outcomes

  1. Total sevoflurane consumption (mL per case), measured at the end of surgery.

    Time frame: throughout the surgery

Secondary outcomes

  1. carbon footprint

    Time frame: throughout the surgery

    Estimated CO₂e emissions (calculated from anesthetic use)

Sponsors and collaborators

Lead sponsor

Dr Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital

Other

Collaborators

  • Ankara Etlik City Hospital

Registry information

Official study title

The Impact of Ultra-Low-Flow Sevoflurane Anesthesia on Carbon Footprint and Cost: A Randomized Controlled Study in Cardiac Surgery Patients

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Jan 2, 2026
Registry last updated
Jun 18, 2026

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

View the official ClinicalTrials.gov record (opens in a new tab)

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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