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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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| FCV Group | Active Comparator | Patients allocated to the FCV group will receive intraoperative mechanical ventilation using a flow-controlled ventilation mode during surgery under general anesthesia. %50 FiO₂ will be applied, and a driving pressure of 12 cmH₂O will be used. Following insufflation, the patient's FiO₂ will be maintained between 0.8 and 1.0 for 20 minutes. After the 20th minute, ventilator settings will be returned to the baseline values. Tidal volume will be generated and recorded by the ventilator according to the driving pressure and the patient's lung mechanics. Minute ventilation will be adjusted based on the target tidal volume. The target tidal volume will be set at 6-8 mL/kg (7 mL/kg) with a respiratory rate of 12 breaths/min. Positive end-expiratory pressure (PEEP) will be maintained at 5 cmH₂O. The respiratory rate will be further titrated to maintain ETCO₂ between 35 and 40 mmHg. |
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| VCV Group | Active Comparator | Patients allocated to the VCV group will receive intraoperative mechanical ventilation using a conventional volume-controlled ventilation mode throughout surgery under general anesthesia. Anesthetic induction, monitoring, and perioperative management will follow the same standardized clinical protocols as those used in the FCV group. Ventilatory parameters, including peak and plateau airway pressures and arterial blood gas measurements, will be collected at identical predefined intraoperative time points. This group serves as the comparator arm for evaluating the effects of volume-controlled ventilation on airway pressures and oxygenation in these patients. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| FCV Group | Procedure | 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. |
| Measure | Description | Time Frame |
|---|---|---|
| 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. | At 20 minutes after insufflation in the intraoperative period. |
| Measure | Description | Time Frame |
|---|---|---|
| The PaO₂ value during perioperative period | The PaO₂ values will be measured and recorded using arterial blood gas analysis. | At the beginning of the insufflation, 60 minutes after insufflation, before extubation, 1 hour after extubation. |
| Peak airway pressure (Ppeak) values during perioperative period. |
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Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Ankara Etlik City Hospital | Recruiting | Ankara | 06000 | Turkey (Türkiye) |
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| ID | Term |
|---|---|
| D009765 | Obesity |
| ID | Term |
|---|---|
| D050177 | Overweight |
| D044343 | Overnutrition |
| D009748 | Nutrition Disorders |
| D009750 | Nutritional and Metabolic Diseases |
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| VCV Group | Procedure | 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. |
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Ppeak will be measured and recorded. |
| At the beginning of the insufflation, 20 minutes after insufflation, 60 minutes after insufflation, before extubation, 1 hour after extubation. |
| Plateau airway pressure (Pplateau) values during perioperative period | Pplateau will be measured and recorded. | At the beginning of the insufflation, 20 minutes after insufflation, 60 minutes after insufflation, before extubation, 1 hour after extubation. |
| D001835 |
| Body Weight |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |