The Effect of Ventilation Strategy on Arterial and Cerebral Oxygenation During Laparoscopic Bariatric Surgery.

Background: We investigated the effect of prolonged inspiratory to expiratory (I/E) ratio ventilation on respiratory mechanics, gas exchange, and regional cerebral oxygen saturation (rSO2) in obese patients undergoing laparoscopic bariatric surgery in the reverse Trendelenburg position.

Methods: Twenty-eight adult patients scheduled for laparoscopic sleeve gastrectomy were enrolled in this prospective observational study. After anesthesia induction, pressure-controlled ventilation was conducted initially at a conventional I/E ratio of 1:2 and a positive end-expiratory pressure of 5 cmH2O. Twenty minutes after pneumoperitoneum, the I/E ratio was changed to 1:1 for 20 min and then to 2:1 for 20 min. Hemodynamic variables, end-tidal carbon dioxide tension, rSO2, arterial blood gas analysis results, and respiratory variables were recorded.

Results: No significant changes in hemodynamic values and rSO2 were observed during the study. Peak airway pressure was significantly lower, but mean airway pressure and dynamic compliance were significantly higher at I/E ratios of 1:1 and 2:1 than during conventional I/E ratio ventilation. Arterial oxygen tension (PaO2) value was significantly higher (p = 0.009), and alveolar-arterial oxygen tension gradient was lower (p = 0.015) at an I/E ratio of 2:1 than during conventional ratio ventilation.

Conclusions: The use of prolonged I/E ratio of 2:1 significantly improved respiratory mechanics and arterial oxygenation without causing hemodynamic derangements or cerebral desaturation during laparoscopic bariatric surgery in the reverse Trendelenburg position.