Dyspnea is a frequent reason for referral to emergency departments, leading to a 30-day mortality rate of up to 10% and a 3-month rehospitalization rate of over 30%.

Multiple etiologies, as well as poor performance of clinical examination and chest radiography, lead to a diagnostic error rate of nearly 30% at the end of emergency department care. These diagnostic errors lead to rehospitalization and an excess mortality rate of more than 50% compared to patients with a correct initial diagnosis, which is explained in particular by the use of inappropriate therapies.

Lung ultrasound is a rapid, non-irradiating, non-invasive, inexpensive, reproducible imaging test that can be used at the bedside. It has a better diagnostic performance than chest radiography, commonly performed in emergency departments.The immediate benefit of lung ultrasound for the most common diagnoses in emergency medicine has already been demonstrated.

From an organizational point of view, a few studies have shown a benefit of lung ultrasound in reducing the time spent in emergency departments and the number of additional examinations necessary for the final diagnosis. However, there is no data in the literature on the longer term impact of its use in the emergency department.

The primary objective is to evaluate the impact of performing lung ultrasound in terms of 3-month mortality and rehospitalization as part of the diagnostic process for patients admitted to the emergency department with dyspnea.

Inclusion Criteria:

• Age ≥ 18 years
• Admission to the emergency department with dyspnea defined by:

The functional sign of dyspnea experienced by the patient; Or a clinical sign of respiratory distress.

- Non-opposition of the patient or patient's family if the patient isn't able

Exclusion Criteria:

• Trauma-induced dyspnea;
• Patient being on palliative care;
• Patient with criteria for initial resuscitation with admission to a critical care unit;
• Pregnant women, women in labour or nursing mothers;
• Persons deprived of liberty by judicial or administrative decision;
• Persons under psychiatric care;
• Persons admitted to a health or social institution for purposes other than research;
• Persons of full age subject to a legal protection measure (guardianship, curatorship);

This study will focus on adult patients consulting for dyspnea in the emergency department of the Edouard-Herriot Hospital (HCL).