Severe closed chest injury leads to multiple rib fractures, causing the local chest wall to lose rib support and softening, and paradoxical breathing, i.e., the chest wall is invaginated in the softened area during inspiration and protrudes outward during expiration, called shackle chest. It is often combined with pulmonary contusions and is an important factor in triggering acute respiratory distress syndrome (ARDS). Etiology: The shackle thorax is a serious blunt injury to the chest resulting in multiple fractures of the ribs, as the anterior and posterior ends of the ribs lose their bony connection, the affected chest wall becomes unstable due to loss of support and forms a softened chest wall, and the negative pressure in the pleural cavity increases during inspiration, and the softened chest wall becomes more concave inward. The negative pressure in the pleural cavity decreases during exhalation, causing the chest wall to bulge outward, which is the opposite direction of chest wall activity from other parts of the chest wall and is called paradoxical breathing or chest wall floating. The causes of injuries of shackle chest are mostly traffic accident injuries, crush injuries, pressure and smash injuries. The incidence of pulmonary contusions and pulmonary contusions is 84% in this group. The floating chest wall caused by shackle chest destroys the stability of the mechanical movement of the thorax, increases the resistance of the respiratory tract and reduces the respiratory efficiency, impairs the ventilatory function and aggravates the respiratory disorder by the concurrent pulmonary injury, resulting in severe Hypoxemia.