Impact of Body Mass Index on Positive End-expiratory Pressure Guided by Electrical Impedance Tomography for Patients Under General Anaesthesia

The induction of general anaesthesia is associated with a fall in lung volume due in particular to a decrease in muscle tone and the formation of denitrogenation atelectasis. Many recent studies insist on the need to apply a so-called "protective" strategy of intraoperative ventilation, which combines the use of recruitment manoeuvres, reduced tidal volume (Vt) (6-8ml/kg) and positive expiratory pressure (PEEP) to prevent these phenomena. However, the setting of PEEP remains debated and several authors agree on the need to individualize ventilatory parameters, particularly in obese patients, without describing the individualization tools. In the ICU, it has been shown that electrical impedance tomography (EIT) can be used to individualise the PEEP level in a simple and non-invasive way. Therefore, we wish to determine whether the use of this technique during general anaesthesia allows for the individualization of PEEP, and whether the value determined is correlated with the body mass index (BMI).