Respiratory Management of Perioperative Obese Patients

In supine obese people, the weight of the abdomen pushes against the diaphragm, causing a cranial displacement of the muscle. This increased pressure inside the pleural cavity causes atelectasis and hypoxemia, worsening the elastic properties of the respiratory system (elastance – cm H₂O of pressure applied to the airways to change the volume of the respiratory system by 1 L). The reduction of aerated lung tissue at end-expiration reduces the functional residual capacity. The application of adequate levels of PEEP can prevent lung collapse. However, inadequate PEEP results in cyclic opening and closing of dependent alveoli, leading to ventilation-induced lung damage.