Flow- Versus Volume-Controlled Ventilation with Individualised Positive End-expiratory Pressure in Robot-assisted Laparoscopic Radical Prostatectomy: A Prospective, Randomised Controlled Trial

The impact of flow-controlled ventilation (FCV) versus volume-controlled ventilation (VCV) on pulmonary oxygenation and mechanical respiratory parameters is unclear in patients who undergo robot-assisted laparoscopic radical prostatectomy (RALRP). This study hypothesised that FCV improves oxygenation and respiratory system mechanics compared with VCV using individualised positive end-expiratory pressure (PEEP) guided by electrical impedance tomography (EIT) during RALRP. This was a single-centre, prospective, two-arm, randomised controlled trial. Fifty patients were randomly allocated (1:1) to FCV ( n = 25) or VCV ( n = 25). In both groups, ventilation included a tidal volume of 7 mL kg − 1 ideal body weight, a normocapnia-targeted respiratory rate, an inspiratory oxygen fraction (FiO₂) of 0.50, and EIT-guided individualised PEEP. The principal endpoint was the arterial oxygen partial pressure-to-fractional inspired oxygen ratio (PaO₂/FiO₂) measured before extubation. Additional endpoints encompassed respiratory system mechanics, regional distribution of ventilation, and lung ultrasound (LUS) scoring. The PaO₂/FiO₂ ratio before extubation was higher in the FCV group than in the VCV group (352.8 ± 48.1 vs. 309.4 ± 86.1; mean difference, 43.4; 95% CI, 2.2–84.6; p = 0.04). Despite similar intraoperative respiratory-system compliance and mechanical power, ventilation distribution was more homogeneous with FCV at T3 and T4 ( p = 0.03 and p = 0.02, respectively). Postoperative pulmonary complications occurred in 3/23 patients (13.0%) in the FCV group and 8/24 (33.3%) in the VCV group ( p = 0.10). Postoperative lung ultrasound scores and hospital length of stay did not differ significantly between groups. In patients undergoing RALRP, FCV was associated with a higher PaO₂/FiO₂ ratio before extubation and more homogeneous ventilation at T3 and T4 compared with VCV. Whether these physiological differences translate into clinically relevant postoperative outcomes requires further investigation. This trial was retrospectively registered on ClinicalTrials.gov database (Number: NCT07453810; Date: 23 February 2026).