Flow-Controlled Versus Volume-Controlled Ventilation in Bariatric Surgery

Condition(s) studied

Investigational drug(s) / intervention(s)

FCV Group: 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: 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.

Study summary

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

Primary outcome measure(s)

• The PaO₂ value 20 minutes after insufflation. — At 20 minutes after insufflation in the intraoperative period.
  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.

Trial sites (1)

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