Rib fractures are frequent injuries found approximately in 10% severe trauma patient. Rib fractures were correlated in many studies with a higher morbidity and mortality. This impaired outcome is mainly due to pulmonary complications consequences including especially pulmonary contusions. Frequently, patients present difficulty deep breathing and coughing. These adverse effects can lead to the development of atelectasis, hypoxia, and respiratory failure with mechanic ventilation recourse. Effective pain management may prevent these complications and reduce the likelihood of developing chronic pain. A multi-modal analgesia regimen is widely employed combining regional and systemic analgesia. Epidural analgesia is considered by many authors to be the gold standard of pain relief although many side-effects are frequently describe including hypotension, urinary retention nausea and vomiting. Paravertebral nerve blockade is an adequate alternative that provide similar quality of analgesia with lower incidence of complication. However, the failure rate associates with PVB is about 13% and it may be associated with hypotension (4.6%), accidental vascular puncture (3.8%), accidental pleural puncture (1.1%) and rarely pneumothorax (0.5%). Recently, a description of the intercostal paraspinal nerve block. This technic was performed for patients undergoing thoracic surgery without complications.More recently, a description of a new approach to provide thoracic analgesia named the Posterior Paramedian subchoroidal (PoPS) block. The authors consider this technique provide an analgesia of the anterior and the posterior branch of adjacent thoracic nerves. The investigators propose to investigate the effect of Posterior exothoracic fascial block.

Inclusion Criteria:

• Major patients (18-80 years old)
• Affiliated to the social security
• Hospitalized following severe trauma associated with at least 2 unilateral ribs fractures
• EVA greater than or equal to 3 when coughing or when mobilizing care.
• Management of the patient in the first 24 hours post trauma.
• Patient not intubated.
• Collection of informed written consent, notification on the anesthesia sheet.

Exclusion Criteria:

• Minor patients,
• Patients under guardianship
• Pregnant or lactating women
• Allergy known to local anesthetics,
• Severe coagulopathy,
• Infection of the puncture site
• Neuromuscular pathology
• Chronic pain patients (long-term treatment with non-inflammatory steroidal, opioid, neuroleptic, antidepressant, antiepileptic),
• Intubated patient