NTRODUCTION: cardiac surgery can lead to pulmonary complications such as hypoxemia and atelectasis. Noninvasive ventilation has been used to prevent and treat such complications. Electrical impedance tomography has been a useful tool in bedside evaluation of ventilation and pulmonary ventilation. OBJECTIVE: To compare the effects of non-invasive ventilation with oxygen therapy in cardiac post-operative patients. MATERIALS AND METHODS: It will be a randomized controlled clinical trial where patients will be divided into two groups: a group that will perform NIV for 1 hour and the group that will only use oxygen therapy. They will be evaluated through Electrical Impedance Tomography and arterial gasometry analysis just before extubation, soon after extubation, during the intervention and after the intervention for a period of 2 hours after extubation. EXPECTED RESULTS: It is expected that the NIV group will present higher pulmonary ventilation and aeration and better gas exchange than the oxygen therapy group, and that the time of therapeutic effect will be higher in the NIV group.