Dynamic Impact of NIV on Diaphragmatic Ultrasound in Patients With Amyotrophic Lateral Sclerosis

The goal of this pilot observational study is to learn about the dynamic impact of the non invasive ventilation on the diaphragm in patient with amyotrophic lateral sclerosis. The main question it aims to answer : can diaphragmatic ultrasound detect differences in diaphragmatic motion (diaphragmactic excursion and diaphragmatic thickening between spontaneous breathing and non-invasive ventilation ? Participants will receive diaphragmatic ultrasound assessments both under spontaneous breathing and during non-invasive ventilation on their day hospital evaluation for ventilatory support.