The most common cardiac surgeries are myocardial revascularization and valve replacement or plastic surgery. In the postoperative period of cardiac surgeries, the incidence of pulmonary complications ranges from 30% to 50% and is associated with increased length of hospital stay and morbidity and mortality. To reduce or minimize the occurrence of these complications, respiratory physiotherapy employs positive pressure reexpansion therapies, such as continuous positive airway pressure (CPAP) and positive pressure support with positive end-expiratory pressure (PS+PEEP).

The goal of this clinical trial is to compare the effects of two positive pressure therapies, CPAP versus PS+PEEP, on the incidence of pulmonary complications in patients in the postoperative period of myocardial revascularization and valve replacement or plastic surgery, with mild to moderate pulmonary dysfunction.

The main question it aims to answer is: Do patients in the immediate postoperative period of myocardial revascularization or valve replacement/plastic surgery, exhibiting mild to moderate pulmonary dysfunction, experience a comparable reversal of pulmonary conditions when treated with PS+PEEP versus CPAP?

Participants will undergo the following assessments: spirometry, respiratory muscle strength testing, handgrip strength testing, and electrical impedance tomography.

In the immediate postoperative period, participants will be randomized into two treatment groups: • Control Group PS+PEEP - application of 4 sets of 20 repetitions with PS to provide a tidal volume equal to 10ml/kg of predicted body weight, PEEP equal to 10 cmH2O, and inspired oxygen fraction (FiO2) to achieve peripheral oxygen saturation (SpO2) between 92-94%; • Experimental Group CPAP - application of CPAP at 10 cmH2O with FiO2 to achieve SpO2 between 92-94% for 30 minutes.

Inclusion Criteria:

• Immediate postoperative period of myocardial revascularization and/or valve replacement or plastic surgery;
• Patients in the preoperative period at risk of developing pulmonary complications, characterized by the presence of at least 2 of the following risk factors: age ≥ 70 years, productive cough, diabetes, history of smoking, chronic obstructive pulmonary disease (COPD) defined by forced expiratory volume in 1 second (FEV1) lower than 75% of predicted, body mass index (BMI) ≥ 27 kg/m2, or only FEV1 lower than 80% and FEV1/forced vital capacity (FVC) ratio lower than 70% of predicted; OR patients in the postoperative period (up to 12 hours after extubation) with mild to moderate complications characterized by a pulmonary complication score lower than 3.

Exclusion Criteria:

• Hemodynamic instability characterized by mean arterial pressure (MAP) lower than 60mmHg and/or acute arrhythmia of any etiology;
• Need for intra-aortic balloon;
• Duration of invasive mechanical ventilation exceeding 24 hours after surgery;
• Pulmonary complication score ≥ grade 3;
• Presence of signs of acute respiratory failure, such as respiratory rate (f) ≥ 25 breaths/min and use of accessory muscles;
• Chest tube with air leak;
• Use of a pacemaker or implantable or external cardioverter-defibrillator.

IPD will be stored at https://domusdados.unifesp.br/ All IPD that results in a publication will be shared upon reasonable request.

IPD will be avaible from 12 months to 36 months after publication.