Esophageal Pressure Versus Gas Exchange to Set PEEP During Intraoperative Ventilation

BACKGROUND: Pneumoperitoneum and Trendelenburg position affect respiratory system mechanics and oxygenation during elective pelvic robotic surgery. The primary aim of this randomized pilot study was to compare the effects of a conventional low tidal volume ventilation with PEEP guided by gas exchange (VGas-guided) versus low tidal volume ventilation tailoring PEEP according to esophageal pressure (VPes-guided) on oxygenation and respiratory mechanics during elective pelvic robotic surgery. METHODS: This study was conducted in a single-center tertiary hospital between September 2017 and January 2019. Forty-nine adult patients scheduled for elective pelvic robotic surgery were screened; 28 subjects completed the full analysis. Exclusion criteria were American Society of Anesthesiologists physical status >= 3, contraindications to nasogastric catheter placement, and pregnancy. After dedicated naso/orogastric catheter insertion, subjects were randomly assigned to VGas-guided (F-IO2 and PEEP set to achieve S-pO2 > 94%) or VPes-guided (PEEP tailored to equalize end-expiratory transpulmonary pressure). Oxygenation (P-aO2/F-IO2) was evaluated (1) at randomization, after pneumoperitoneum and Trendelenburg application; (2) at 60 min; (3) at 120 min following randomization; and (4) at end of surgery. Respiratory mechanics were assessed during the duration of the study. RESULTS: Compared to VGas-guided, oxygenation was higher with VPes-guided at 60 min (388 +/- 90 vs 308 +/- 95 mm Hg, P = .02), at 120 min after randomization (400 +/- 90 vs 308 +/- 81 mm Hg, P = .008), and at the end of surgery (402 +/- 95 vs 312 +/- 95 mm Hg, P = .009). Respiratory system elastance was lower with VPes-guided compared to VGas-guided at 20 min (24.2 +/- 7.3 vs 33.4 +/- 10.7 cm H2O/L, P = .001) and 60 min (24.1 +/- 5.4 vs 31.9 +/- 8.5 cm H2O/L, P 5.006) from randomization. CONCLUSIONS: Oxygenation and respiratory system mechanics were improved when applying a ventilatory strategy tailoring PEEP to equalize expiratory transpulmonary pressure in subjects undergoing pelvic robotic surgery compared to a VGas-guided approach.