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% O(2) 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.