Flow-controlled versus volume-controlled ventilation during bariatric surgery

Comparison of Flow-Controlled and Volume-Controlled Ventilation During Bariatric Surgery: A Prospective Randomized Trial

NA · Ankara Etlik City Hospital · NCT07430111

This trial will see if flow-controlled ventilation or volume-controlled ventilation gives better oxygen levels and lower airway pressures during bariatric surgery in adults with obesity.

Quick facts

PhaseNA
Study typeInterventional
Enrollment40 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorAnkara Etlik City Hospital (other gov)
Locations1 site (Ankara)
Trial IDNCT07430111 on ClinicalTrials.gov

What this trial studies

Adults aged 18–65 with a BMI of 30 kg/m² or higher and ASA physical status II–III who are undergoing bariatric surgery will be assigned to receive either flow-controlled ventilation (FCV) or volume-controlled ventilation (VCV) during general anesthesia. Ventilatory parameters including peak and plateau airway pressures, pulmonary compliance, and arterial oxygen tension (PaO2) will be recorded at predefined intraoperative time points. The primary endpoint is PaO2 measured at the 20th minute while on an FiO2 of 0.8–1.0. The study compares intraoperative oxygenation and airway mechanics to identify whether one ventilation mode offers better physiologic outcomes in obese surgical patients.

Who should consider this trial

Good fit: Adults 18–65 years old with BMI ≥30 kg/m², ASA physical status II–III, no significant preexisting pulmonary disease, and scheduled for bariatric surgery are ideal candidates.

Not a fit: Patients outside the age or ASA ranges, those with known significant pulmonary disease or severe preoperative respiratory impairment, and those requiring chronic supplemental oxygen are unlikely to benefit from the findings.

Why it matters

Potential benefit: If successful, this could improve intraoperative oxygenation and reduce airway pressures during bariatric surgery, which may lower the risk of perioperative pulmonary complications.

How similar studies have performed: Physiological studies and small clinical series have suggested FCV can lower airway pressures and improve compliance versus conventional modes, but its benefit specifically in obese bariatric patients is not well established.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age between 18 and 65 years
* Body mass index (BMI) ≥ 30 kg/m²
* ASA physical status II-III

Exclusion Criteria:

* ASA physical status I or IV and above
* Known or previously diagnosed pulmonary disease
* Patients with severe preoperative pulmonary function impairment (e.g., FEV₁ \< 50% predicted, severe restrictive or obstructive pathology)
* Patients with markedly altered lung anatomy or function due to prior major thoracic surgery
* Patients who were dependent on supplemental oxygen therapy in the preoperative period
* Refusal to participate in the study or inability to comply with study procedures

Where this trial is running

Ankara

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Obesity, Bariatric Surgery, Mechanical Ventilation, Flow-Controlled Ventilation, Volume-Controlled Ventilation

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.