Any thoracic trauma causes more or less severe hypoxia, due to pain, pleural effusion, mechanical ventilation disorders and pulmonary contusion. These four factors lead to bronchial congestion, which in turn aggravates hypoxia. More or less rapidly a vicious circle of respiratory failure is created. It can be broken only by early treatment of the cause. Without such treatment, respiratory failure quickly becomes autonomic and treatment of the cause is no longer sufficient.