Intraoperative Driving Pressure and Postoperative Lung Ultrasound Score in Robot-Assisted Radical Prostatectomy

The primary outcome is the difference in lung aeration between preoperative baseline (LUS 0, at T0: pre-induction, awake, supine) and 24 hours postoperatively (LUS 2). Lung aeration is evaluated via a 12-region ultrasound protocol; each quadrant is scored 0-3, yielding a total of 0-36 (higher scores indicate worse aeration). This change (LUS 0 to LUS 2) will be correlated with the mean intraoperative driving pressure (ΔP = Pplat - PEEP). Mean ΔP is calculated as the average of measurements obtained at predefined intraoperative milestones: T_basal (immediately post-intubation), T1 (1st hour, immediately post-establishment of pneumoperitoneum and deep Trendelenburg), T2, T3, T4, T5 (hourly intervals during pneumoperitoneum/Trendelenburg maintenance), and T_neutral (within 10 minutes post-desufflation, return to supine).

This outcome assesses early postoperative lung aeration changes between baseline (LUS 0, at T0: pre-induction, awake, supine) and 30 minutes postoperatively in the post-anesthesia care unit (LUS 1). Aeration is evaluated via a 12-region ultrasound protocol (each quadrant scored 0-3; total 0-36). This acute change (LUS 0 to LUS 1) will be correlated with mean intraoperative driving pressure (ΔP = Pplat - PEEP). Mean ΔP is the average of measurements at specific milestones: T_basal (immediately post-intubation), T1 (1st hour, post-establishment of pneumoperitoneum and deep Trendelenburg), T2, T3, T4, T5 (hourly maintenance), and T_neutral (within 10 minutes post-desufflation, return to supine).

This outcome investigates the correlation between total anesthesia/mechanical ventilation duration (measured in minutes from T0: pre-induction to extubation) and changes in lung aeration. The clinical impact of operative time on atelectasis will be evaluated by correlating this duration with early (LUS 0 at T0 to LUS 1 at postop 30 min) and persistent (LUS 0 to LUS 2 at postop 24 hours) LUS changes. The intraoperative timeline includes predefined milestones: T_basal (post-intubation), T1 (1st hour, post-pneumoperitoneum and deep Trendelenburg), T2, T3, T4, T5 (hourly maintenance), and T_neutral (post-desufflation, return to supine).

This outcome evaluates cumulative energy delivered to the respiratory system (Mechanical Power, MP) during volume-controlled ventilation. Average (MP_mean) and maximum (MP_max) MP will be retrospectively calculated via the simplified Gattinoni formula using ventilator data at milestones: T_basal (immediately post-intubation), T1 (1st hour, post-pneumoperitoneum and deep Trendelenburg), T2, T3, T4, T5 (hourly maintenance), and T_neutral (post-desufflation). These intraoperative energy metrics will be correlated with early (LUS 0 to LUS 1 at 30 min) and persistent (LUS 0 to LUS 2 at 24 hours) postoperative changes in lung aeration.

This outcome assesses immediate physiological impacts of driving pressure (ΔP) changes induced by pneumoperitoneum and deep Trendelenburg. Arterial blood gas (ABG) parameters, specifically pH, PaO2/FiO2 ratio (Horowitz index), PaCO2, and lactate, will be correlated with the ΔP (Pplat - PEEP) measured at exact corresponding milestones: T_basal (immediately post-intubation), T1 (1st hour, immediately post-establishment of pneumoperitoneum and deep Trendelenburg), T2, T3, T4, T5 (hourly maintenance), and T_neutral (within 10 minutes post-desufflation, return to supine).

This outcome tracks postoperative pulmonary complications (PPCs) to evaluate the clinical impact of intraoperative ventilation. PPCs are defined as transient or persistent desaturation (SpO2 < 92%), clinical need for supplemental oxygen, or tachypnea in the PACU. This incidence is correlated with the mean intraoperative driving pressure (ΔP) calculated as the average across milestones: T_basal (post-intubation), T1 (1st hour, post-pneumoperitoneum and deep Trendelenburg), T2, T3, T4, T5 (hourly maintenance), and T_neutral (post-desufflation, return to supine). Clinical follow-up extends up to 24 hours.