Influence of Inspiratory Pause on Ventilatory Efficiency in Robotic Surgery. A Prospective Paired Study.

"Phase 1:~Moment (M) 1) Standard PPV and an initial EIP of 10%~M 2) ARM with titration of optimal PEEP (PEEPop) on a decremental PEEP trial, followed by a new ARM and setting a tailored open-lung PEEP (tOL-PEEP), that 2 cm H2O higher than PEEPop~M 3) Incremental modification of the EIP in steps of 10% (from 10 to 40%)"

"Phase 2:~M 4) The investigators will apply the EIP that guarantees the lowest Pdriv~M 5) After applying pneumoperitoneum and trendelenburg~M 6) Atelectasis test (see below)~M 7) M 7a) In case of atelectasis test = negative: the investigators will modify the EIP in incremental or decremental steps of 10% M 7b) In case of atelectasis test=positive: ARM~M 8) In those cases recruited (M 7b), modify the EIP (as in M 7a)~Once the EIP that guarantees the best ventilation conditions has been stablished based on the lowest Pdriv (and higher Crs), the investigators will maintain these conditions until the end of surgery, with periodic evaluation of the pulmonary collapse by means of the atelectasis test (see below) performed every 40 minutes or regardless of time if an oxygen saturation by pulse oximetry (SpO2) \< 97% is detected."

It is performed during mechanical ventilation, due to suspicion of alveolar collapse. Alveolar collapse will be suspected on observation of a reduction in Crs \> 10% over post-recruitment values. In these cases the atelectasis test will be performed, consisting of a reduction in FiO2 to 0.21, maintaining this FiO2 for 5 minutes. If lung collapse is \>10%, a fall in SpO2 below 97% will be expected (positive atelectasis test), in which case, an ARM and a PEEPop titration test will be performed.