A Prospective, Randomized, Clinical Trial on the Effects of a Valveless Trocar on Respiratory Mechanics During Robotic Radical Cystectomy: A Pilot Study

BACKGROUND: Prolonged pneumoperitoneum and Trendelenburg positioning for robot-assisted radical cystectomy (RARC) are essential for optimizing visualization of the operative field, although they worsen hemodynamic and respiratory function. Our hypothesis is that the use of a valveless trocar (VT) may improve respiratory mechanics. METHODS: In this prospective, 2-arm parallel trial, patients ASA II to III undergoing RARC were randomly assigned into 2 groups: in the VT group, the capnoperitoneum was maintained with a VT; in the control group, the capnoperitoneum was maintained with a standard trocar (ST group). Inspiratory plateau pressure (Pplat), static compliance (Cstat), minute volume (MV), tidal volume (Vt), and carbon dioxide (CO2) elimination rate were recorded at these times: 15 minutes after anesthesia induction (T0), 10 minutes (T1) and 60 minutes (T2) after first robot docking, 10 minutes before first undocking (T3), 10 minutes (T4) and 60 minutes (T5) after second docking, 10 minutes before second undocking (T6), and 10 minutes before extubation (T7). The primary end point of the study was the assessment of Pplat mean value from T1 to T6. RESULTS: A total of 56 patients were evaluated: 28 patients in the VT group and 28 in the ST group. VT group had lower Pplat (means and standard error, VT group 30 [0.66] versus ST group 34 [0.66] cm H2O, with estimated mean difference and 95% confidence interval, -4.1 [-5.9 to -2.2], P <.01), lower MV (means and standard error, VT group 8.2 [0.22] versus ST group 9.8 [0.21] L min(-1), P <.01), lower CO2 elimination rate (means and standard error, VT group 4.2 [0.25] versus ST group 5.4 [0.24] mL kg(-1) min(-1), P <.01), lower end-tidal CO2 (etco(2)) (means and standard error, VT group 28.8 [0.48] versus ST group 31.3 [0.46] mm Hg, P <.01), and higher Cstat (means and standard error, VT group 26 [0.9] versus ST group 22.1 [0.9] mL cm H2O-1, P <.01). Both groups had similar Vt (P =.24). CONCLUSIONS: During RARC, use of a VT was associated with a significantly lower Pplat and improvement in other respiratory parameters.