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Flow-Controlled Versus Volume-Controlled Ventilation in Bariatric Surgery

ConditionsObesityBariatric SurgeryMechanical Ventilation
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-65
SponsorAnkara Etlik City Hospital

About this trial

This prospective trial aims to compare the effects of flow-controlled ventilation (FCV) and volume-controlled ventilation (VCV) on intraoperative airway pressures and oxygenation in bariatric surgery under general anesthesia. Obesity is associated with altered respiratory mechanics, reduced functional residual capacity, and increased airway pressures, making the selection of an optimal ventilation strategy particularly important in this patient population.

Adult patients aged 18-65 years with a body mass index ≥30 kg/m² and American Society of Anesthesiologists (ASA) physical status II-III will be allocated to receive either FCV or VCV as part of routine intraoperative mechanical ventilation. Ventilatory parameters, including peak and plateau airway pressures, pulmonary compliance, will be recorded at predefined intraoperative time points.

The primary endpoint of the study is the PaO₂ value measured at the 20th minute under an FiO₂ of 0.8-1.0.

By providing comparative data on respiratory mechanics and oxygenation, this study aims to contribute to the identification of lung-protective ventilation strategies and to optimize intraoperative ventilatory management in bariatric surgery.

Eligibility criteria

This trial does not accept healthy volunteers

Qualifiers

Age between 18 and 65 years

Body mass index (BMI) ≥ 30 kg/m²

ASA physical status II-III

Disqualifiers

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

Trial design

Design model

Parallel

Treatments tested in this trial

  • FCV Group

    Procedure/Surgery

    Patients allocated to the FCV group will receive intraoperative mechanical ventilation using a flow-controlled ventilation mode during surgery under general anesthesia. Patients will be started on ventilation after intubation with 50% oxygen, driving pressure 12, PEEP 5, and a 1:1 inspiration/expiratory ratio.

  • VCV Group

    Procedure/Surgery

    Patients allocated to the VCV group will receive intraoperative mechanical ventilation using a conventional volume-controlled ventilation mode throughout surgery under general anesthesia. Patients will be started on ventilation after intubation with 50% oxygen, 7 ml/ideal body weight tidal volume, PEEP 5, 12 breaths per minute frequency, and a 1:2 inspiration/expiration ratio.

Treatment groups

40 Participants
are divided into 2 treatment groups
Group A: FCV GroupActive comparator 1 intervention
Group B: VCV GroupActive comparator 1 intervention

Trial outcomes

Primary outcomes

1

The PaO₂ value 20 minutes after insufflation.

The primary endpoint of the study is the PaO₂ value measured at the 20th minute under an FiO₂ of 0.8-1.0. Following insufflation, the patient's FiO₂ will be maintained between 0.8 and 1.0 for 20 minutes. The primary endpoint of the study is the PaO₂ value measured at the 20th minute under an FiO₂ of 1.0. After the 20th minute, ventilator settings will be returned to the baseline values.

Time frame
At 20 minutes after insufflation in the intraoperative period.

Secondary outcomes

1

The PaO₂ value during perioperative period

The PaO₂ values will be measured and recorded using arterial blood gas analysis.

Time frame
At the beginning of the insufflation, 60 minutes after insufflation, before extubation, 1 hour after extubation.
2

Peak airway pressure (Ppeak) values during perioperative period.

Ppeak will be measured and recorded.

Time frame
At the beginning of the insufflation, 20 minutes after insufflation, 60 minutes after insufflation, before extubation, 1 hour after extubation.
3

Plateau airway pressure (Pplateau) values during perioperative period

Pplateau will be measured and recorded.

Time frame
At the beginning of the insufflation, 20 minutes after insufflation, 60 minutes after insufflation, before extubation, 1 hour after extubation.

Other outcomes

Sponsors and contacts

Click on the lead sponsor to view all of their trials.

Ankara Etlik City Hospital

Lead sponsor

Source ClinicalTrials.gov
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