Predictability of Echographic Excursion of the Diaphragm for Intubation in COPD- Patients With Acute Respiratory Failure in ED

Inclusion of every lawful age patient presenting to the ER with inclusion criterias The patient must not have exclusion criteria and must have received the information and consent sheets to be signed jointly Then, the investigators perform an online randomization for the first and second operator and the side (left/right) from which they start the ultrasound assessment. The investigators then assess diaphragmatic excursion measurements in spontaneously ventilated patient at 45 ° proclive position for each hemi-diaphragm, with the 2 operators blinded to each other, for 3 consecutive respiratory cycles and save the images. The date of inclusion is then reported in the register.