The aim of this study was to investigate the effects of using positive pressure in the preoperative, intraoperative and postoperative morbidly obese individuals undergoing gastroplasty.

It is believed that the application of these devices before, during or after surgery can help to improve the lungs and reduce pulmonary complications after surgery to reduce the stomach.

The aim of this study was to investigate the effects of using positive pressure in the preoperative, intraoperative and postoperative morbidly obese individuals undergoing Roux-en-Y gastric bypass with regard to: lung volumes and capacities, the prevalence of atelectasis, duration of surgery and diaphragmatic mobility.

Individuals with BMI between 40 and 55 kg/m2, aged between 25 and 55 years, were submitted to Roux-en-Y type gastric bypass by laparotomy. Patients showing a normal preoperative pulmonary function test were included, but those with hemodynamic instability, a hospital stay longer than three days or the presence of postoperative complications were excluded.

The volunteers were divided into four different groups:

Gpre: subjects treated with positive pressure in the BiPAP mode (Bi-Level Positive Airway Pressure) for one hour before surgery; Gpos: individuals treated with positive airway pressure (BiPAP) for one hour after surgery; Gpeep: individuals treated with 10 cm H2O of PEEP (Positive End Expiratory Pressure) during the surgical procedure.

Gcont: individuals treated with conventional physiotherapy (CP) according to the routine service of physiotherapy of the hospital, including the techniques of pulmonary re-expansion, breathing exercises (deep breaths or fractional), the use of incentive spirometry (Respiron®), bronchial hygiene resources if necessary (Flutter® and cough active or assisted) and assisted ambulation. It should be noted that the physiotherapist was blinded to the individual's participation in the groups, and all patients received conventional physiotherapy, independent of the group in which they were included.

The respiratory evaluation (preoperative and second postoperative days) consisted of collecting the anthropometric data, a pulmonary function test and a chest radiography (inspired and expired).

Inclusion Criteria:

• BMI between 40 and 55 kg/m2
• Aged between 25 and 55 years
• Submitted to Roux-en-Y type gastric bypass by laparotomy
• Normal preoperative pulmonary function test

Exclusion Criteria:

• Hemodynamic instability
• Hospital stay longer than three days
• Presence of postoperative complications