Positive end-expiratory pressure setting based on transpulmonary pressure during robot-assisted laparoscopic prostatectomy: an observational intervention study

BACKGROUND: In robot-assisted laparoscopic prostatectomy (RALP), concerns include the formation of atelectasis and reduced functional residual capacity. The present study aimed to examine the feasibility of positive end-expiratory pressure (PEEP) setting based on transpulmonary pressure (Ptp) as well as the effects of incremental PEEP on respiratory mechanics, blood gases, cerebral oxygenation (rSO(2)), and hemodynamics. METHODS: Fourteen male patients who were scheduled to receive RALP were recruited. Patients received mechanical ventilation (tidal volume of 6 mL kg(−1)) and were placed in Trendelenburg position with positive-pressure capnoperitoneum. PEEP levels were increased from 0 to 15 cmH(2)O (5 cmH(2)O per increase) every 30 min. PEEP levels were assessed where end-expiratory Ptp levels of ≥0 cmH(2)O were achieved (PtpEEP0). Airway pressure, esophageal pressure, cardiac index, and blood gas and rSO(2) values were measured after 30 min at each PEEP step and respiratory mechanics were calculated. RESULTS: With increasing PEEP levels from 0 to 15 cmH(2)O or PtpEEP0, the values of PaO(2) and respiratory system compliance increased, and the values of driving pressure decreased. The median PEEP level associated with PtpEEP0 was 15 cmH(2)O. Respiratory system compliance values were higher at PtpEEP0 than those at PEEP5 (P = 0.02). Driving pressure was significantly lower at PtpEEP0 than at PEEP5 (P = 0.0036). The cardiac index remained unchanged, and the values of rSO(2) were higher at PtpEEP0 than at PEEP0 (right; P = 0.0019, left; P = 0.036). CONCLUSIONS: PEEP setting determined by transpulmonary pressure can help achieve higher respiratory system compliance values and lower driving pressure without disturbing hemodynamic parameters.