Flail Chest

Flail Chest- A Review

Rajesh Purushothaman, Associate Professor, Orthopaedics, Medical College, Calicut, Kerala, India

• 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.
• 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. 2^nd to 7^th ribs are connected to sternum by costal cartilage.
• 8^th to 10^th rib costal cartilages fuse together and then with the 7^th costal cartilage. 11^th and 12^th 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.

Management Principles

• The aim of initial management is to avoid further lung injury, adequate analgesia and to ensure adequate oxygenation. Supplemental high flow oxygen should be given to all patients. Adequate analgesia is required not only on humanitarian considerations but for improved respiratory function.
• Opioids should be avoided if possible to avoid respiratory depression. Intercostal blockade is an excellent method for analgesia. Epidural analgesia is also a good option and is the method of choice.

• Age>65years, respiratory distress, previous lung disease, shock, severe associated injuries, severe head injury, and fracture of > 8 ribs are indication for mechanical ventilation using intermittent positive pressure ventilation.
• Mechanical ventilation must be continued for 7-14 days. Main problem with mechanical ventilation is hospital acquired infections. Constant airway positive pressure (CAPP) mode of ventilation is found to be most useful. Surgical fixation of flail chest may be indicated in a minority.
• Surgical fixation reduces the duration of ventilatory support and reduces mortality and septicemia in those without lung contusion. In those with associated lung contusion, surgical fixation doesn’t offer additional benefits.

• Management of lung contusion is the most important part of management. Lung contusion is hemorrhage into lung parenchyma secondary to extrinsic injury.
• Presence of lung contusion is the most important determinant of prognosis. It leads to further collection of interstitial fluid, ventilation-perfusion mismatch and respiratory compromise.
• Normal cellular responses to injury are harmful in the lungs as it creates a barrier between the alveolar air and capillary blood vessels increasing the diffusion distance for oxygen and CO2.
• Oxygen diffusion barrier is not improved by intermittent positive pressure ventilation (IPPV). Patients with lung contusion are managed by fluid restriction, diuretics, rigorous pulmonary toilet, steroids and albumin.
• Fluid restriction creates important challenges in management of polytraumatised, but there is strong evidence for hypotensive resuscitation in those with lung contusion. Use of colloids or blood products and restriction of crystalloids is advisable in presence of lung contusion.
• Fluid management should be monitored using central venous pressure or pulmonary artery pressure and an even or slightly negative fluid balance should be maintained.

 

• Trinkle regimen is utilized for management of lung contusion, it consists of intravenous fluid restriction, furosemide 40mg on admission and then 40mg daily for the next 3 days, Methylprednisolone 500mg IV on admission then qds for 3 days, salt-poor albumin, replace intravascular volume with plasma or whole blood, vigorous tracheobronchial toilet, morphine and intercostal nerve blocks for analgesia and supplemental oxygen to maintain pO2>80mmHg.
• Present evidence is against excessive fluid restriction, and as per present recommendations patient should be resuscitated with blood or crystalloids but unnecessary fluid overload must be avoided.
• Present recommendation is also against use of mechanical ventilation as treatment for chest wall instability; mechanical ventilation is used for correction of abnormalities of gas exchange. Routine use of steroids is also discouraged as per current recommendations.

Dr Rajesh Purushothaman, Email: drrajeshpurushothamanATyahoo.com