After conventional cardiac surgery, many respiratory complications are possible. Therefore, the resuscitator prescribe physiotherapy and non invasive ventilation. The physiotherapist has few reliable tools to evaluate and follow the patient on his ventilatory function. Currently, lung ultrasound is little used in physiotherapy and no study explains the link between the lung ultrasound results and oxygenation patient state. Before considering the interest of lung ultrasound score as a criterion of effectiveness of a physiotherapy treatment through future studies, it is first important to objectivize the existence of a relationship between lung ultrasound score and the PaO2/FiO2 ratio after cardiac surgery. Lung ultrasound could provide direct clinical information without having to resort to other more invasive examinations to objectify the improvement of the patient's oxygenation.

Main objective To show that the relative change in the PaO2/FiO2 ratio correlates with the change in lung ultrasound score measured in the short term between the beginning and the end of the first physiotherapy session associated with non invasive ventilation the day after surgery in cardiac patients

Secondary objectives

• To study the inter-operator (2 readers) reproducibility of the lung ultrasound score measurement.
• To study the relationship between the relative variation of the PaO2/FiO2 ratio and the variation of each of the 12 zones of the lung ultrasound score
• To Study the relationship between the initial lung ultrasound score and the relative variation of the PaO2/FiO2 ratio
• To study the relative variation of the PaCO2 and the variation of the lung ultrasound score between the beginning and the end of the first session of physiotherapy management associated with NIV
• To obtain from the patient in the short term feedback on his or her understanding of the explanations about lung ultrasound score provided by the physiotherapist during the session

Inclusion Criteria:

• Person having received complete information on the organization of the research and having given written consent to participate
• Person having benefited from a heart surgery under cardio-pulmonary bypass
• Medical prescriptions for non invasive ventilation and physiotherapist
• Age ≥ 18 years
• 18.5 ≤ BMI ≤ 35 kg/m2
• Visual Analogy Scale pain < 4
• Patient conscious and oriented: Glasgow 15/15

Exclusion Criteria:

• At the patient's request : a patient may withdraw from the research at any time without affecting the quality of care to which he or she is entitled (withdrawal of consent).
• Cardiorespiratory arrest during the inclusion visit.
• Need for orotracheal reintubation during the inclusion visit.
• Patient non-cooperation during the inclusion visit.
• Failure of the ultrasound machine during the inclusion visit.
• Failure of the blood gas analyzer.
• Glasgow < 15 during the inclusion visit
• PEEP > 6 cmH2O required during physiotherapy + non invasive ventilation session
• PEEP < 6 cmH2O required during physiotherapy + non invasive ventilation session
• Premature interruption of the physiotherapy session + non invasive ventilation not hemodynamically tolerated
• Need for a session of non invasive ventilation + physiotherapy > 30 minutes.