The main objective of this study is to evaluate the inter-rater reproducibility of diaphragmatic excursion measures via time-motion-mode ultrasound (evaluation performed on the first measure) in patients experiencing acute respiratory distress emergencies.

The secondary objectives of this study are:

• To assess the feasibility of measuring the diaphragmatic excursion in the context of emergency management (ratio of measured patients / included patients).
• To evaluate the time required for the measurement.
• To assess the intra-rater reproducibility of measurements of diaphragmatic excursion (comparison of first and second measures).

Inclusion Criteria:

• The patient must have given his/her informed and signed consent
• The patient must be insured or beneficiary of a health insurance plan
• The patient has acute respiratory distress defined by a respiratory rate > 25, and / or signs of struggle and hypoxia, oxygen saturation (SpO2) <90% and / or pH <7.35 and carbon dioxide partial pressure (pCO2) > 6 kPa (45 mm Hg)
• The patient breathes spontaneously (no respirator)

Exclusion Criteria:

• The patient is participating in another study
• The patient is in an exclusion period determined by a previous study
• The patient is under judicial protection, under tutorship or curatorship
• The patient or his/her representative refuses to sign the consent
• It is impossible to correctly inform the patient, or to correctly inform his/her representative
• The patient is pregnant, parturient, or breastfeeding
• The patient has a neurological or neuromuscular disease that modifies diaphragm function/movement; this does not include cases of decompensation (polyradiculoneuropathy, Lou Gehrig's disease, Myasthenia ...).
• Patient admitted with respiratory support treatment in progress
• Patient admitted with respiratory failure requiring immediate implementation of mechanical ventilation, thus preventing ultrasound measurements