Ultra-Low-Flow Anesthesia and Carbon Footprint

NCT07313969 | Completed DMC

• 1 other identifier: Ultra_low_flow
• Study Type: interventional
• Target: 92
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Low Flow Anesthesia; Sevoflurane Anesthesia; Cardiac Surgery

Keywords

low flow anesthesia; ultra low flow anesthesia; carbon footprint

Outcome Measures

Primary Outcomes (1)

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

  throughout the surgery

Secondary Outcomes (1)

• carbon footprint

  throughout the surgery

Study Arms (2)

Ultra-Low-Flow Group (0.5 L/min)

ACTIVE COMPARATOR

Sevoflurane anesthesia with fresh gas flow maintained at 0.5 L/min throughout the maintenance period. A 2 lt/min fresh gas flow will be used in the preoxygenation and intubation phase. General anesthesia will be maintained with sevoflurane at a fresh gas flow rate of 0.5 L/min using an oxygen and air mixture. The flow rate will be kept constant from post-induction stabilization until the end of the surgery. Ventilation will be paused during cardiopulmonary bypass.

Drug: ultra low flow anesthesia

Normal-Flow Group (2.0 L/min)

ACTIVE COMPARATOR

Sevoflurane anesthesia with fresh gas flow maintained at 2.0 L/min throughout maintenance period. The flow rate will be kept constant from post-induction stabilization until the end of surgery. Ventilation will be paused during cardiopulmonary bypass

Drug: normal flow anesthesia

Interventions

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.

Ultra-Low-Flow Group (0.5 L/min)

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.

Normal-Flow Group (2.0 L/min)

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

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

You may not qualify if:

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

Sponsors & Collaborators

• Ankara Etlik City Hospital: collaborator
• Dr Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital: lead

Study Sites (1)

Etlik City Hospital

Ankara, Ankara, 06810, Turkey (Türkiye)

Location

Related Publications (1)

• McGain F, Sheridan N, Wickramarachchi K, Yates S, Chan B, McAlister S. Carbon Footprint of General, Regional, and Combined Anesthesia for Total Knee Replacements. Anesthesiology. 2021 Dec 1;135(6):976-991. doi: 10.1097/ALN.0000000000003967.

  PMID: 34529033 BACKGROUND

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Masking Details: Participants and postoperative outcome assessors will be blinded to group allocation. The anesthesia provider cannot be blinded due to visible gas flow settings; however, they will not be involved in postoperative data collection or analysis.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: consultant anesthesiologist

Study Record Dates

• First Submitted: December 10, 2025
• First Posted: January 2, 2026
• Study Start: July 30, 2025
• Primary Completion: September 15, 2025
• Study Completion: January 15, 2026
• Last Updated: January 27, 2026

Record last verified: 2025-12

Locations

TU (1)