Open Lung Approach Versus Conventional Protective Ventilation in Obese Patients Undergoing Open Abdominal Surgery

"The ARM is performed by setting the peak inspiratory pressure to 45 cmH₂O then changing the mode of ventilation to pressure controlled ventilation (PCV) with the inspiratory pressure set to give a tidal volume equal to that given during VCV, I:E ratio of 1:1 and a PEEP of 5 cmH₂O. The PEEP level is then increased in 5 cmH₂O steps every minute till it reaches 20 cmH₂O and inspiratory pressure is increased to get an airway opening pressure (inspiratory pressure + PEEP) of 40 cmH₂O which is maintained for one minute after which the ventilation returned to the original setting except for the PEEP level which is kept at 20 cmH₂O.~The titration of individualized PEEP is done by decremental reduction of the 20 cmH₂O PEEP level in 2 cmH₂O steps every 2 minutes and measuring static compliance of the respiratory system (CRS) at each step."

volume controlled ventilation (7ml/kg tidal volume) with addition of 5 cm H₂O fixed PEEP till the end of the surgery .