Flow-Controlled Versus Volume-Controlled Ventilation in Lumbar Disc Herniation Surgery

Ankara Etlik City Hospital

Status: Enrolling

Conditions: Lumbar Disc Herniation Surgery; Mechanical Ventilation

Treatments: Procedure: FCV Group; Procedure: VCV Group

Study type: Interventional

Funder types: Other

Identifiers

NCT07614555

AEŞH-EK-2026-096

Details and patient eligibility

About

This prospective randomized trial aims to compare the effects of flow-controlled ventilation (FCV) and volume-controlled ventilation (VCV) on intraoperative airway pressures and oxygenation in patients undergoing lumbar disc herniation surgery under general anesthesia.

Adult patients aged 18-65 years, with ASA physical status I-III and a body mass index of 18-30 kg/m², will be allocated to receive either FCV or VCV during routine intraoperative mechanical ventilation. Ventilatory parameters, including peak airway pressure, plateau pressure, pulmonary compliance, EtCO₂, SpO₂, and arterial blood gas variables, will be recorded at predefined time points after intubation.

The primary endpoint is the PaO₂ value measured after 20 minutes in the prone position.

By comparing respiratory mechanics and oxygenation between the two ventilation modes, this study aims to contribute to the optimization of intraoperative ventilatory management in lumbar disc herniation surgery.

Enrollment: 80 estimated patients

Sex: All

Ages: 18 to 65 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Age between 18 and 65 years
• ASA physical status I-III
• Body Mass Index between 18 and 30 kg/m²

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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80 participants in 2 patient groups

FCV Group

Active Comparator group

Description:

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. After intubation, the patient will be placed in the prone position. Following the prone position, 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.

Treatment:

Procedure: FCV Group

VCV Group

Active Comparator group

Description:

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.

Treatment:

Procedure: VCV Group