Flow-Controlled Versus Volume-Controlled Ventilation During Balloon Dilatation Under Direct Laryngoscopy

Comparison of Flow-Controlled and Volume-Controlled Ventilation During Balloon Dilatation Under Direct Laryngoscopy: A Prospective Randomized Trial

This prospective trial aims to compare the effects of flow-controlled ventilation (FCV) and volume-controlled ventilation (VCV) on airway pressures and oxygenation in adult patients undergoing balloon dilatation under direct laryngoscopy. Airway procedures performed under general anesthesia are associated with unique respiratory mechanics and limited ventilation conditions, making the choice of an optimal ventilation strategy particularly important.

Adult patients aged 18-65 years with American Society of Anesthesiologists (ASA) physical status I-III will be allocated to receive either FCV or VCV during surgery. Ventilatory parameters, airway pressures, pulmonary compliance, and arterial blood gas values will be recorded at predefined intraoperative time points. The primary outcome is the PaO₂ measured 20 minutes under an FiO₂ of 0.8-1.0 after starting the ventilation under general anesthesia, reflecting early intraoperative oxygenation under stable conditions.

By providing comparative data on respiratory mechanics and oxygenation, this study aims to contribute to the identification of lung-protective ventilation strategies in patients undergoing balloon dilatation under direct laryngoscopy.

Inclusion Criteria:

• Age between 18 and 65 years
• ASA physical status I-III

Exclusion Criteria:

• Age < 18 years or > 65 years
• 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
• ASA physical status IV or higher
• Refusal or inability to provide informed consent