In patients undergoing NIV for acute respiratory, lack of tolerance is one of the main reason of failure.~This may result in a poor synchrony between the patient and the machine, leading to gross mismatching and potentially to an increased work of breathing.~The investigators aim to investigate whether in these patients poorly responding to NIV the use of a sedation protocol using remifentanil will lead to an improve patient-ventilator interaction and better compliance to NIV.~In this physiological study the investigators will study 15 patients at risk of failing NIV because of scarce tolerance and showing clinical signs of poor interaction with the ventilator.~Once the patient will be enrolled the investigators will record using the balloon-catheter technique the online measurement of respiratory mechanics, to assess the inspiratory muscle effort and the matching between the patient breathing pattern and that of the ventilator The investigators will also record the clinical success of sedation (i.e. need or not for endotracheal intubation)
In patients undergoing NIV for acute respiratory, lack of tolerance is one of the main reason of failure.~This may result in a poor synchrony between the patient and the machine, leading to gross mismatching and potentially to an increased work of breathing.~The investigators aim to investigate whether in these patients poorly responding to NIV the use of a sedation protocol using remifentanil will lead to an improve patient-ventilator interaction and better compliance to NIV.