Comparison of volume-controlled and pressure-controlled ventilation in steep Trendelenburg position for robot-assisted laparoscopic radical prostatectomy

Study Objective: To compare the effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) on respiratory mechanics and hemodynamics in steep Trendelenburg position. Design: Prospective, randomized clinical trial. Setting: University hospital. Patients: 34 ASA physical status 1 and 2 patients undergoing RLRP. Interventions: Patients were randomly allocated to either the VCV (n = 17) or the PCV group (n = 17). After induction of anesthesia, each patient's lungs were ventilated in constant-flow VCV mode with 50% O₂ and tidal volume of 8 mL/kg; a pulmonary artery catheter was then inserted. After establishment of 30° Trendelenburg position and pneumoperitoneum, VCV mode was switched to PCV mode in the PCV group. Measurements: Respiratory and hemodynamic variables were measured at baseline supine position (T1), post-Trendelenburg and pneumoperitoneum 60 minutes (T2) and 120 minutes (T3), and return to baseline after skin closure (T4). Main Results: The PCV group had lower peak airway pressure (AP_peak) and greater dynamic compliance (C_dyn) than the VCV group at T2 and T3 (P < 0.05). However, no other variables differed between the groups. Pulmonary arterial pressure and central venous pressure increased at T2 and T3 (P < 0.05). Cardiac output and right ventricular ejection fraction were unchanged in both groups. Conclusions: PCV offered greater C_dyn and lower AP _peak than VCV, but no advantages over VCV in respiratory mechanics or hemodynamics.