Mechanical in-exsufflation devices (MI-E) are a non-invasive chest physiotherapy (CPT) technique that aims to improve mucus clearance in proximal airways by generating high expiratory flows and simulating cough. Currently there are no studies that have specifically assessed the effects of MI-E in critically ill and intubated patients. Thus, the aims of this study are to evaluate efficacy and safety of MI-E to improve mucus clearance in critically ill and intubated patients.