Eligibility Criteria
This study included patients of both sexes, aged 18 years or older and who underwent to coronary artery bypass grafting with median sternotomy and cardiopulmonary bypass. Patients with hemodynamic instability before noninvasive ventilation, who were not cooperative or who had contraindications for the use of NIV, chronic pulmonary disease, absence of blood gas analysis in some of the study phases, physical limitations that compromised the performance of functional tests were excluded (amputation), difficulty understanding to perform the applied tests, surgical reintervention, more than 24 hours in invasive mechanical ventilation and patients who refused to sign the consent form.