Evaluation of the Relevance of Diaphragmatic Stroke Ultrasound for the Etiological Diagnosis of Acute Respiratory Distress in an Emergency Department.

Inclusion Criteria:

• Patients 18 years of age or older;

• Patient with ARD defined by respiratory rate (RR) strictly superior to 25 and/orsigns of struggle which are: thoraco-abdominal rocking, active abdominal breathing,recruitment of extra-diaphragmatic respiratory muscles AND

• peripheral saturation (SpO2) strictly inferior to 90% and/or hypercapnic acidosis (pH strictly inferior to 7.35 and pCO2 strictly superior to 45mmHg) on arterialblood gases;

• Spontaneous ventilation.

• Patients presenting a clinical severity score of Grade 1 with signs of struggle, aswell as those with Grade 2 and Grade 3. A clinical severity score will be used asfollows: Grade 1: Minimal polypnoea with respiratory rate (RR) between 20 and 25 ;Grade 2: Moderate polypnoea with respiratory rate (RR) between 25 and 35; Grade 3:Major polypnoea with respiratory rate (RR) between 35 to 50.

Exclusion Criteria:

• Adult protected by law (guardianship, curatorship, legal protection)

• Refusal of consent after information

• Patient on non-invasive ventilation ;

• Patient on mechanical ventilation;

• Respiratory rate superior to 50/min

• Patient currently being treated for infectious pneumopathy with antibiotics;

• Pregnant or breast-feeding women;

• Patients with any known history of diaphragmatic pathologies.

• Illiterate or unable to understand the purpose and methodology of the study.

• Patient not affiliated to a social security scheme or not benefiting from such ascheme.

• Person deprived of liberty (by judicial or administrative decision, or forcedhospitalization)

• Person participating in another study with an exclusion period still in progress,