Low-Flow Anesthesia Without Wash-in: Effects on Oxygenation and Depth of Anesthesia

NCT07534839 | Active Not Recruiting DMC

• 1 other identifier: ErzincanBinaliYildirim
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to evaluate whether adjusting the fresh gas flow rate to low-flow immediately after intubation, without performing a wash-in, is a reliable approach with respect to depth of anesthesia and oxygenation.

Conditions

Low Flow Anesthesia

Keywords

general anesthesia; green anesthesia; low flow anesthesia

Outcome Measures

Primary Outcomes (2)

• Comparison of arterial oxygen partial pressure (PaO₂) values between groups

  Comparison of arterial oxygen partial pressure (PaO₂) and Patient State Index (PSI) values between groups.

  Measured at 10, 20, 30, and 45 minutes after induction of anesthesia and before the end of surgery.

• Comparison of Patient State Index (PSI) values between groups.

  PSI is an EEG-based index ranging from 0 to 100. Lower values indicate deeper anesthesia; the target range is 25-50 during general anesthesia.

  Continuously monitored intraoperatively and recorded at 10, 20, 30, and 45 minutes after induction of anesthesia.

Secondary Outcomes (3)

• Mean alveolar concentration (MAC) values

  Continuously monitored intraoperatively and recorded at 10, 20, 30, and 45 minutes after induction of anesthesia.

• Total sevoflurane consumption

  From induction of anesthesia until the end of surgery (average duration approximately X minutes).

• Time to reach target MAC level

  Time (minutes) from completion of endotracheal intubation to achievement of MAC 1.0, as measured on the anesthesia monitor

Study Arms (2)

Group WI

NO INTERVENTION

In this group, after intubation, patients were ventilated for 10 minutes with 4 L/min fresh gas flow consisting of 2% sevoflurane and 60% O₂, after which the fresh gas flow rate was reduced to 0.75 L/min

Group WO

ACTIVE COMPARATOR

In this group, after intubation, the fresh gas flow rate was set to 0.75 L/min with 60% O₂. The sevoflurane vaporizer was initially set to 8%, and the sevoflurane concentration was subsequently reduced according to the MAC value

Device: Initiation of low-flow anesthesia without wash-in following intubation

Interventions

Initiation of low-flow anesthesia without wash-in following intubation DEVICE

After endotracheal intubation, fresh gas flow is set to 0.75 L/min with 60% O₂. The sevoflurane vaporizer is initially set to 8%, and the sevoflurane concentration is subsequently titrated according to the target MAC value. Anesthesia depth and oxygenation are monitored using PSI monitoring and serial arterial blood gas measurements.

Group WO

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• ASA physical status I-II
• Cases lasting longer than 30 minutes
• Non-laparoscopic surgical procedures

You may not qualify if:

• Patients with life-threatening renal, cardiac, or hepatic disease
• Patients with chronic pulmonary diseases such as asthma or COPD
• Patients with intraoperative hemodynamic instability
• Patients with a body mass index (BMI) lower than 20 or higher than 30

Sponsors & Collaborators

• Erzincan Binali Yildirim Universitesi: lead

Study Sites (1)

Binali Yildirim Univercity

Erzincan, Erzincan, 24000, Turkey (Türkiye)

Location

Related Publications (7)

• Simsek T, Derman S, Kordi RGM, Saracoglu A, Saracoglu KT. The effect of different flow levels and concentrations of sevoflurane during the wash-in phase on volatile agent consumption: a randomized controlled trial. J Clin Monit Comput. 2022 Oct;36(5):1257-1262. doi: 10.1007/s10877-022-00846-w. Epub 2022 Apr 19.

  PMID: 35438367 BACKGROUND

• Bahar S, Arslan M, Urfalioglu A, Gisi G, Oksuz G, Bilal B, Oksuz H, Doganer A. Low-flow anaesthesia with a fixed fresh gas flow rate. J Clin Monit Comput. 2019 Feb;33(1):115-121. doi: 10.1007/s10877-018-0135-2. Epub 2018 Mar 23.

  PMID: 29572589 BACKGROUND

• Amirfarzan H, Cassidy KJ, Moaddab M, Demin M, Schumann R, Lewis B. Assessment of seizure duration and utility of using SedLine(R) EEG tracing in veterans undergoing electroconvulsive therapy: a retrospective analysis. J Anesth Analg Crit Care. 2024 Feb 6;4(1):8. doi: 10.1186/s44158-024-00143-9.

  PMID: 38321515 BACKGROUND

• McIlroy DR, Shotwell MS, Lopez MG, Vaughn MT, Olsen JS, Hennessy C, Wanderer JP, Semler MS, Rice TW, Kheterpal S, Billings FT 4th; Multicenter Perioperative Outcomes Group. Oxygen administration during surgery and postoperative organ injury: observational cohort study. BMJ. 2022 Nov 30;379:e070941. doi: 10.1136/bmj-2022-070941.

  PMID: 36450405 BACKGROUND

• Dastan R, Kefeli Celik H, Doganay Z. High, Low, and Minimal Flow Anaesthesia Management: Effects on Oxygen Reserve Index and Arterial Partial Oxygen Pressure. J Coll Physicians Surg Pak. 2023 Nov;33(11):1223-1228. doi: 10.29271/jcpsp.2023.11.1223.

  PMID: 37926871 BACKGROUND

• Varughese S, Ahmed R. Environmental and Occupational Considerations of Anesthesia: A Narrative Review and Update. Anesth Analg. 2021 Oct 1;133(4):826-835. doi: 10.1213/ANE.0000000000005504.

  PMID: 33857027 BACKGROUND

• Kutlusoy S, Koca E, Aydin A. Reliability of low-flow anesthesia procedures in patients undergoing laparoscopic cholecystectomy: Their effects on our costs and ecological balance. Niger J Clin Pract. 2022 Nov;25(11):1911-1917. doi: 10.4103/njcp.njcp_387_22.

  PMID: 36412300 BACKGROUND

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: March 29, 2026
• First Posted: April 16, 2026
• Study Start: March 1, 2026
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): August 1, 2026
• Last Updated: April 16, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will share

Locations

TU (1)