AtelectasisNCT07041567
Low-Flow Anesthesia and Perioperative Atelectasis in Laparoscopic Bariatric Surgery
A study testing Sevoflurane with normal-flow anesthesia and Sevoflurane with low-flow anesthesia in people with Atelectasis and Pulmonary Complications, run by Istanbul University at 1 site in Turkey (Türkiye).
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Atelectasis, Pulmonary Complications, Ultrasonography
- What is being tested?
- Sevoflurane with normal-flow anesthesia and Sevoflurane with low-flow anesthesia
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- 15 Jan 2026to 15 Apr 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
Turkey (Türkiye)1 site
Göztepe Prof.Dr. Süleyman Yalçın Şehir Hastanesi
Istanbul, Goztepe, 34000
About this study
Official title: Effect of Low-Flow Anesthesia on Perioperative Atelectasis in Patients Undergoing Laparoscopic Bariatric Surgery: A Randomized Controlled Trial
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?
Read more
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
Read the detailed description
This prospective, single-center, randomized controlled trial investigates the effect of low-flow anesthesia on perioperative atelectasis in patients undergoing elective laparoscopic sleeve gastrectomy. Morbidly obese patients are at increased risk of perioperative atelectasis due to reduced functional residual capacity, diaphragmatic elevation, and the additional physiological burden of pneumoperitoneum and reverse Trendelenburg positioning during laparoscopic surgery.
Eligible patients are randomized in a 1:1 ratio to one of two groups. In the normal-flow group (Group N), anesthesia is maintained with sevoflurane at a fresh gas flow of 2 L/min. In the low-flow group (Group D), anesthesia is initiated at 4 L/min to achieve rapid equilibration and then reduced to 0.5 L/min once 1.0 minimum alveolar concentration (MAC) is reached. All patients receive standardized lung-protective mechanical ventilation and an identical anesthetic protocol otherwise.
Atelectasis is quantified using the modified Lung Ultrasound Scoring System (mLUSS), in which each of 12 lung zones is scored 0-3 based on aeration loss, yielding a total score of 0-36. Assessments are performed preoperatively, at postoperative hour 1, and at postoperative hour 24 by a single investigator blinded to group allocation. Pulmonary function tests (FVC, FEV₁, FEV₁/FVC, PEF, FEF₂₅-₇₅) are performed preoperatively and at postoperative hour 48 by a separate blinded investigator.
Secondary outcomes include changes in spirometric parameters, intraoperative hemodynamic event incidences, mean intraoperative FiO₂ and plateau pressure, sevoflurane and remifentanil consumption, postoperative nausea and vomiting incidence, and postoperative analgesic requirements.
- Conditions
- Atelectasis, Pulmonary Complications, Ultrasonography, Bariatric Surgery, Low Flow Anesthesia
- Being tested
- Sevoflurane with normal-flow anesthesia, Sevoflurane with low-flow anesthesia
- Medical subject headings
- Pulmonary Atelectasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Sevoflurane with normal-flow anesthesiaDrug
Sevoflurane is delivered via inhalation with a fresh gas flow of 2 L/min throughout surgery. Vaporizer is set to 2.5%.
Sevoflurane with low-flow anesthesiaDrug
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.
| Study group | Role | What they receive |
|---|---|---|
| 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. Receives: 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. Receives: Drug: Sevoflurane with low-flow anesthesia |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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)
Between-group difference in the change in mLUSS from preoperative baseline to postoperative hour 24
Measured: 24 hours postoperatively
Changes in spirometric parameters from baseline to postoperative hour 48
Between-group differences in the change in FVC, FEV₁, FEV₁/FVC, PEF, and FEF₂₅-₇₅ from preoperative baseline to postoperative hour 48.
Measured: 48 hours postoperatively
Intraoperative hemodynamic event incidences
Incidences of hypotension, hypertension, bradycardia, tachycardia, oxygen desaturation, and hypercapnia during surgery, compared between groups.
Measured: Intraoperatively
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Jun 2025
- Study start15 Jan 2026
- Primary completion1 Apr 2026
- Study completion15 Apr 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AtelectasisStudies of the same condition, open and under way.
- More trials run by Istanbul UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 60 participants (actual)
Sponsor and investigators
- Lead sponsor
- Istanbul University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dunyakhanim Farzaliyeva, Goztepe Prof Dr Suleyman Yalcın City Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07041567
- Sponsor's protocol ID
- BCAİA-AUD28
- Status last verified
- May 2026
- First submitted
- 16 Jun 2025
- Last updated
- 20 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared. This is a single-center academic study; data are available from the corresponding author upon reasonable request.
Study at a glance
From the registry record, last updated by the sponsor on 20 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Low-Flow Anesthesia on Perioperative Atelectasis in Patients Undergoing Laparoscopic Bariatric Surgery: A Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07041567
- Acronym / sponsor ID
- BCAİA-AUD28
- Conditions
- Atelectasis, Pulmonary Complications, Ultrasonography, Bariatric Surgery, Low Flow Anesthesia
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 60 participants (actual)
- Lead sponsor
- Istanbul UniversityUniversity, hospital or other
- Study start
- 15 Jan 2026 (actual)
- Primary completion
- 1 Apr 2026 (actual)
- Study completion
- 15 Apr 2026 (actual)
- First posted
- 27 Jun 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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
Detailed description
This prospective, single-center, randomized controlled trial investigates the effect of low-flow anesthesia on perioperative atelectasis in patients undergoing elective laparoscopic sleeve gastrectomy. Morbidly obese patients are at increased risk of perioperative atelectasis due to reduced functional residual capacity, diaphragmatic elevation, and the additional physiological burden of pneumoperitoneum and reverse Trendelenburg positioning during laparoscopic surgery.
Eligible patients are randomized in a 1:1 ratio to one of two groups. In the normal-flow group (Group N), anesthesia is maintained with sevoflurane at a fresh gas flow of 2 L/min. In the low-flow group (Group D), anesthesia is initiated at 4 L/min to achieve rapid equilibration and then reduced to 0.5 L/min once 1.0 minimum alveolar concentration (MAC) is reached. All patients receive standardized lung-protective mechanical ventilation and an identical anesthetic protocol otherwise.
Atelectasis is quantified using the modified Lung Ultrasound Scoring System (mLUSS), in which each of 12 lung zones is scored 0-3 based on aeration loss, yielding a total score of 0-36. Assessments are performed preoperatively, at postoperative hour 1, and at postoperative hour 24 by a single investigator blinded to group allocation. Pulmonary function tests (FVC, FEV₁, FEV₁/FVC, PEF, FEF₂₅-₇₅) are performed preoperatively and at postoperative hour 48 by a separate blinded investigator.
Secondary outcomes include changes in spirometric parameters, intraoperative hemodynamic event incidences, mean intraoperative FiO₂ and plateau pressure, sevoflurane and remifentanil consumption, postoperative nausea and vomiting incidence, and postoperative analgesic requirements.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Normal-Flow Anesthesia Group (Group N) | Active comparator | Drug: Sevoflurane with normal-flow anesthesiaPatients 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. |
| Low-Flow Anesthesia Group (Group D) | Experimental | Drug: Sevoflurane with low-flow anesthesiaPatients 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. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- 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
Key exclusion criteria (1 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Sevoflurane with normal-flow anesthesiaSevoflurane is delivered via inhalation with a fresh gas flow of 2 L/min throughout surgery. Vaporizer is set to 2.5%. | Drug | Normal-Flow Anesthesia Group (Group N) |
| Sevoflurane with low-flow anesthesiaSevoflurane 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. | Drug | Low-Flow Anesthesia Group (Group D) |
Primary outcome
Change in modified Lung Ultrasound Score from baseline to postoperative hour 1 (ΔmLUSS₁ₕ)
Time frame: 1 hour after arrival to the post-anesthesia care unit (PACU)
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.
3 secondary outcomes
Change in modified Lung Ultrasound Score from baseline to postoperative hour 24 (ΔmLUSS₂₄ₕ)
Time frame: 24 hours postoperatively
Changes in spirometric parameters from baseline to postoperative hour 48
Time frame: 48 hours postoperatively
Intraoperative hemodynamic event incidences
Time frame: Intraoperatively
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 20 May 2026.
- Individual participant dataSharing planned: No. Individual participant data will not be shared. This is a single-center academic study; data are available from the corresponding author upon reasonable request.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Sevoflurane with normal-flow anesthesia and Sevoflurane with low-flow anesthesia in people with Atelectasis and Pulmonary Complications, run by Istanbul University at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 20 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in modified Lung Ultrasound Score from baseline to postoperative hour 1 (ΔmLUSS₁ₕ) (time frame: 1 hour after arrival to the post-anesthesia care unit (PACU)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 20 May 2026.