Low-Flow Anesthesia and Perioperative Atelectasis in Laparoscopic Bariatric Surgery

NCT07041567 | Completed

• 1 other identifier: BCAİA-AUD28
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this clinical trial is to learn whether low-flow anesthesia reduces perioperative atelectasis compared to normal-flow anesthesia in adults undergoing laparoscopic bariatric surgery. The main questions it aims to answer are: Does low-flow anesthesia result in a smaller increase in lung ultrasound score from baseline to postoperative hour 1? Does low-flow anesthesia result in better preservation of pulmonary function at postoperative hour 48? Researchers will compare low-flow anesthesia (fresh gas flow 0.5 L/min) to normal-flow anesthesia (fresh gas flow 2 L/min) to see if low-flow anesthesia reduces the extent of perioperative atelectasis as measured by lung ultrasound. Participants will: Be randomly assigned to receive either low-flow or normal-flow inhalational anesthesia with sevoflurane during surgery Undergo lung ultrasound assessments before surgery and at postoperative hours 1 and 24 Undergo spirometric testing one day before surgery and at postoperative hour 48

Conditions

Atelectasis; Pulmonary Complications; Ultrasonography; Bariatric Surgery; Low Flow Anesthesia

Outcome Measures

Primary Outcomes (1)

• Change in modified Lung Ultrasound Score from baseline to postoperative hour 1 (ΔmLUSS₁ₕ)

  The mLUSS is calculated by scoring 12 lung zones (0-3 per zone) based on aeration loss on lung ultrasound, yielding a total score of 0-36. The primary outcome is the between-group difference in the change from preoperative baseline to postoperative hour 1.

  1 hour after arrival to the post-anesthesia care unit (PACU)

Secondary Outcomes (3)

• Change in modified Lung Ultrasound Score from baseline to postoperative hour 24 (ΔmLUSS₂₄ₕ)

  24 hours postoperatively

• Changes in spirometric parameters from baseline to postoperative hour 48

  48 hours postoperatively

• Intraoperative hemodynamic event incidences

  Intraoperatively

Study Arms (2)

Normal-Flow Anesthesia Group (Group N)

ACTIVE COMPARATOR

Patients receive normal-flow inhalational anesthesia with sevoflurane throughout surgery. Fresh gas flow (FGF) is maintained at 2 L/min with the sevoflurane vaporizer set to 2.5%. Lung-protective mechanical ventilation is applied uniformly.

Drug: Sevoflurane with normal-flow anesthesia

Low-Flow Anesthesia Group (Group D)

EXPERIMENTAL

Patients receive low-flow inhalational anesthesia with sevoflurane. Anesthesia is initiated at FGF 4 L/min with sevoflurane at 6% for rapid equilibration; once end-tidal sevoflurane reaches 1.0 MAC, FGF is reduced to 0.5 L/min and titrated to maintain 1.0 MAC throughout surgery.

Drug: Sevoflurane with low-flow anesthesia

Interventions

Sevoflurane with normal-flow anesthesia DRUG

Sevoflurane is delivered via inhalation with a fresh gas flow of 2 L/min throughout surgery. Vaporizer is set to 2.5%.

Normal-Flow Anesthesia Group (Group N)

Sevoflurane with low-flow anesthesia DRUG

Sevoflurane is delivered via inhalation. Anesthesia is initiated at FGF 4 L/min with vaporizer at 6% for rapid equilibration. Once end-tidal sevoflurane reaches 1.0 MAC, FGF is reduced to 0.5 L/min and titrated to maintain 1.0 MAC.

Low-Flow Anesthesia Group (Group D)

Eligibility Criteria

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

You may qualify if:

• Age 18-65 years ASA physical status III Scheduled for elective laparoscopic sleeve gastrectomy under general anesthesia Able to provide written informed consent and cooperate with study procedures

You may not qualify if:

• Severe respiratory comorbidities (advanced COPD, restrictive lung disease, or severe obstructive sleep apnea syndrome) Advanced heart failure (ejection fraction \< 20%) Chronic renal failure Hepatic insufficiency Uncontrolled diabetes mellitus Uncontrolled hypertension Limited capacity to cooperate with study procedures

Sponsors & Collaborators

• Istanbul University: lead

Study Sites (1)

Göztepe Prof.Dr. Süleyman Yalçın Şehir Hastanesi

Istanbul, Goztepe, 34000, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Pulmonary Atelectasis

Interventions

Sevoflurane

Condition Hierarchy (Ancestors)

Lung Diseases; Respiratory Tract Diseases

Intervention Hierarchy (Ancestors)

Methyl Ethers; Ethers; Organic Chemicals; Hydrocarbons, Fluorinated; Hydrocarbons, Halogenated; Hydrocarbons

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: RESIDENT DOCTOR

Study Record Dates

• First Submitted: June 16, 2025
• First Posted: June 27, 2025
• Study Start: September 1, 2025
• Primary Completion: February 1, 2026
• Study Completion: February 28, 2026
• Last Updated: May 4, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)