Abstract
Background
Obesity causes a reduction in the functional residual capacity (FRC), significant atelectasis and shunting in dependent lung regions. In bariatric surgery under general anesthesia the application of positive end expiratory pressure (PEEP) improves the arterial oxygen tension (PaO2) via increasing function residual capacity, prevention of surfactant aggregation which reduces alveolar collapse.
Patients and methods
In our prospective randomized controlled comparative study, a total of 69 patients who were non-smoker, ASA II and scheduled for laparoscopic sleeve gastrectomy were included. Patients were randomly allocated to three groups, 23 patients each, group C: control group including patients on mechanical ventilation without any PEEP applied, group A: in which an ascending pattern of PEEP was applied till the end of surgery and group D: in which a descending pattern of PEEP was applied till the end of surgery.
Results
Regarding oxygen saturation (SPO2) and PaO2 distribution from time 30 till 90 minutes, group A and group D were significantly higher than group C, while arterial carbon dioxide tension (PaCO2) and End tidal CO2 (ETCO2) in both group A and group D were significantly lower than group C but at different times. Mean airway pressure and PIP were significantly higher in groups A and D than group C.
Conclusion
PEEP 7 cmH2o is the best ventilation strategy among the studied strategies regarding hemodynamic parameters and lung mechanics, but oxygenation and ventilation improve with any PEEP level.