Flail chest

Please note… This is my article published in http://www.orthopaedicprinciples.comhttp://orthopaedicprinciples.com/2013/01/flail-chest/

Thoracic injury is the direct cause of 25% of deaths after trauma and is a contributory factor in another 25% of deaths. Most of these deaths are due to blunt thoracic trauma and flail chest can be a major component of these injuries. Early mortality in flail chest syndrome is due to underlying lung contusion or massive hemothorax and late mortality is mainly due to ARDS. The cause of blunt thoracic trauma is most commonly due to rapid deceleration or crushing in road traffic accidents. This is usually found in front seat passengers of car crashes.

Definition

Flail chest occurs when 3 or more consecutive ribs are fractured at 2 or more places on shaft of the rib. This leads to an unstable segment that moves paradoxically during the respiratory cycle. There are two types of flail chest; sternal flail and lateral flail chest. Paradoxical movement means outward movement during expiration and inward during inspiration. Presence of flail chest suggests high velocity trauma. It may be associated with intrathoracic injuries like pneumothorax, hemothorax, lung contusion, cardiac trauma or diaphragmatic rupture. Severe flail chest may lead to respiratory failure even in the absence of other thoracic injuries. In later stages it may lead to pneumonia and septicemia.

Anatomy

Thoracic cage is formed by 12 ribs with their costal cartilages connected anteriorly to the sternum and posteriorly to the vertebral column to form a ring. First rib is fused to the manubrium and move as one. It is protected by the clavicle and its fracture suggests a high velocity trauma. 2nd to 7th ribs are connected to sternum by costal cartilage. 8th to 10th rib costal cartilages fuse together and then with the 7th costal cartilage. 11th and 12th ribs are floating ribs.

Pathophysiology

Thoracic trauma can lead to respiratory insufficiency with hypoxia or circulatory insufficiency with hypotension. Two contributing factors associated with flail chest are underlying lung contusion and paradoxical chest wall movement. Paradoxical movement leads to abnormal ventilation mechanics with decreased total lung capacity (TLC) and functional residual capacity (FRC).

Management

In management of these injuries; check ABCs, do primary survey to rule out any immediate life threatening injury like airway obstruction, tension pneumothorax, open pneumothorax, massive hemothorax, cardiac tamponade and flail chest. Stabilize the patient and examine again to rule out potential life threatening injuries like lung contusion, myocardial contusion, aortic dissection, esophageal rupture, diaphragmatic rupture tracheobronchial rupture etc.

Do diagnostic studies such as blood routine, arterial blood gas analysis and ECG. X-ray chest if possible in erect posture is the most important investigation to rule out flail chest. Careful evaluation of CXR is required as 50% of rib fractures are not visualized on x-ray. Fracture of first three ribs or scapula suggest high velocity trauma. Fracture of lower 4 ribs may be associated with intra-abdominal injury. Pulmonary contusion is evidenced in a variety of appearances that vary from diffuse infiltrate to total white out of lung fields. Serial x-rays should be taken at appropriate intervals during management. CT is much more sensitive in detecting underlying pathology.

To read further please visit

My article published in http://www.orthopaedicprinciples.comhttp://orthopaedicprinciples.com/2013/01/flail-chest/

Copyright @Dr Rajesh Purushothaman, Associate Professor, Government Medical College, Kozhikode, Kerala, India

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