During robot-assisted laparoscopic radical prostatectomy (RALRP), patients are placed under general anesthesia and supported with mechanical ventilation. In this study, the effects of two different ventilatory strategies-flow-controlled ventilation (FCV) and volume-controlled ventilation (VCV)-were compared. Using electrical impedance tomography (EIT) to provide real-time assessment of lung status and to guide individualized positive end-expiratory pressure (PEEP) settings, we investigated whether FCV offers superior oxygenation and improved respiratory system mechanics compared with VCV.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
50
Mechanical ventilation delivered in a flow-controlled mode with constant inspiratory and expiratory flow patterns
Mechanical ventilation delivered in a volume-controlled mode with constant tidal volume and decelerating inspiratory flow pattern.
Etlik City Hospital
Ankara, Ankara, Turkey (Türkiye)
The ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2)
The primary outcome is the PaO2/FiO2 before extubation (T4).
Time frame: During the intraoperative period at four predefined time points: after induction of general anesthesia (T1), after pneumoperitoneum and Trendelenburg positioning (T2), 60 minutes after T2 (T3), and before extubation (T4).
Driving pressure
Driving pressure is measured as the difference between plateau pressure and positive end-expiratory pressure (PEEP), with values obtained directly from the ventilator display in the VCV group. In the FCV group, tracheal driving pressure is recorded from the ventilator and corrected for endotracheal tube resistance to calculate alveolar driving pressure, allowing physiologically comparable measurements between groups.
Time frame: During the intraoperative period at four predefined time points: after induction of general anesthesia (T1), after pneumoperitoneum and Trendelenburg positioning (T2), 60 minutes after T2 (T3), and before extubation (T4).
Mechanical power
Mechanical power (MP) is calculated from recorded ventilatory parameters. In the volume-controlled ventilation (VCV) group, MP is calculated using respiratory rate, tidal volume, peak airway pressure, and driving pressure. In the flow-controlled ventilation (FCV) group, MP is calculated using minute ventilation, peak pressure, PEEP, and inspiratory flow.
Time frame: During the intraoperative period at four predefined time points: after induction of general anesthesia (T1), after pneumoperitoneum and Trendelenburg positioning (T2), 60 minutes after T2 (T3), and before extubation (T4).
Lung ultrasound score
Lung ultrasound (LUS) examination is performed with the patient in the supine position using an ultrasound device equipped with a low-frequency (2.5-5 MHz) convex probe suitable for intercostal imaging. The thoracic surface is systematically evaluated in both longitudinal and transverse planes. For standardized assessment, each hemithorax is divided into anterior, lateral, and posterior regions, and each region is further subdivided into upper and lower areas, resulting in a total of 12 scanning zones. Normal aeration, defined as the presence of A-lines or fewer than two isolated B-lines with preserved lung sliding, is scored as 0. The presence of three or more well-spaced B-lines with preserved sliding is scored as 1. Coalescent B-lines indicating moderate loss of aeration are scored as 2. Pulmonary consolidation is scored as 3. The total LUS score ranges from 0 to 36, with higher scores indicating greater loss of lung aeration.
Time frame: Lung ultrasound scores (LUS) are assessed at two time points: immediately before anesthesia induction and on the first postoperative day.
pulmonary/extrapulmonary complications
Time frame: The first seven postoperative days
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