Protective ventilatory strategy should be applied to reduce ventilator-induced lung injury (VILI) after Lung Transplantation (LTx) or in case of acute respiratory failure requiring invasive mechanical ventilation. Neurally Adjusted Ventilatory Assist (NAVA) is an assisted ventilation mode in which respiratory support is coordinated by the electrical activity of the diaphragm (EAdi). Aim of the study is to assess the physiological relationship between neural respiratory drive, as assessed by EAdi, and tidal volume, driving pressure, and mechanical power, at different levels of ventilatory assist, in the absence of pulmonary vagal afferent feedback or during acute respiratory failure. Additional parameters will be collected: Pmus, Pocc, transpulmonary pressure etc.
Age > 18 y.o.
Admission to ICU for post-operative monitoring after LTx or acute respiratory failure needing invasive mechanical ventilation
Presence of spontaneous breathing activity
Sedation titrated to a target RASS between 0 and -2
Contraindication to nasogastric tube insertion (gastroesophageal surgery in the previous 3 months, gastroesophageal bleeding in the previous 30 days, history of esophageal varices, facial trauma)
Increased risk of bleeding with nasogastric tube insertion, due to severe coagulation disorders and severe thrombocytopenia ( i.e., INR > 2 and platelets count < 70.000/mm3)
Severe hemodynamic instability (noradenaline > 0.3 μg/kg/min and/or use of vasopressin)
Postoperative extracorporeal respiratory support (ECMO)