Flail Chest Injury – Causes, Presentation and Treatment

Flail chest is caused by severe blunt injury which causes multiple [3 or more] segmental [rib fractures at two points say anterior and posterior] rib fracture resulting in paradoxical movement of broken chest wall segment [that becomes devoid of any attachment and moves with changes in intrathoracic pressure.]

With a better understanding of injury pattern, the treatment of flail chest has greatly evolved from placing towel clips on broken segments to orotracheal intubation with positive pressure ventilation to pneumatically stent the ribcage to modern surgical fixation of the segments.

Flail chest variations include posterior flail segments, anterior flail segments, and flail including the sternum with ribs on both sides of the thoracic cage fractured.

Significant force is required to cause this injury. It requires a significant force diffused over a large area of the thorax for flail chest to occur by creating multiple anterior and posterior rib fractures.

In the case of osteoporotic ribs, lower forces may cause the injury.

In addition to the injury to the chest wall, the amount of injury to the underlying structures, specifically the lungs and heart are more important for the outcome of flail chest.

The exact incidence of flail chest is not precisely known. Bimodal distribution has been noted – adults and elderly.

Flail chest in a neonate/ child has been reported as a potential marker of child abuse.

Associated injuries are scapula fractures, clavicle fractures, and hemothorax and/or pneumothorax

Causes and Pathophysiology

Flail chest is caused by significant trauma to the chest. This may be due to

• Motor vehicle accidents
• Falls
• Assaults in younger

Preexisting conditions like osteoporosis, total sternectomy, and multiple myeloma, as well as individuals with congenital absence of the sternum can have flail chest with lesser force.

Presentation

There is a history of chest injury and patient presents with severe chest pain and difficulty in breathing.  Paradoxical or reverse motion of a chest wall segment while spontaneously breathing suggests flail chest.

The inherent structural stability of the chest wall due to the ribs and intercostal muscles usually does not show abnormal or paradoxical motion without 3 or more ribs involved. Therefore if a flail segment is noted on examination, it indicates 3 or more broken ribs.

However, the paradoxical movement is not noted after intubation with positive pressure ventilation, which may result in results in a delayed diagnosis.

The degree of respiratory insufficiency is typically related to the underlying lung injury, rather than the chest wall abnormality.

Diagnosis

Lab studies have a role in the management of flail chest and its fallouts but not physiologic abnormalities, but no  t in the diagnosis of flail chest.

Arterial blood gas (ABG) measurements demonstrate the severity of the hypoventilation and are helpful at baseline to assess the requirement for mechanical ventilation

Chest x-rays though are able to show the fractures but may not show all fracture sites.

AP or PA chest x-ray is sufficient. Plain films can miss rib fractures and pneumothoraces but id flail chest is clinically observed, the injury pattern should be looked for intently.

Saggital and coronal reconstruction of thoracic CT scan can be used to identify the rib fractures and evaluation of other possible injuries as well.

Treatment of Flail Chest

Pain control and pulmonary care, including medical management of their pulmonary injury is the standard treatment.  Mechanical ventilation is indicated in patients with persistent respiratory insufficiency or failure after good pain control or when the complications associted with drug use occur.

The various options for pain control are patient-controlled analgesia,  oral pain medications, and indwelling epidural catheters

Surgical stabilization of the chest, though not routinely performed has found an increased role in recent times. It is worth assertion again that respiratory failure is more due to pulmonary injury than injury to the chest wall. Therefore fixation is not indicated routinely.

In general, operative fixation is most commonly performed in patients

• Requiring a thoracotomy for other reasons or in cases of gross chest wall deformity.
• Flail chest in presence of
  • Multiple myeloma
  • Sternal absence [Total sternectomy]
• Open fractures

Surgical rib fixation has been found to decrease the number of ventilator days by as much four times.

Complications

• Chest wall pain
• Intercostal neuralgia
• Periscapular muscle weakness
• Pneumonia
• Dyspnea on exertion or Restrictive type pulmonary function
• Chest deformity

Prognosis

5-10% reported mortality has been reported in patients who reach the hospital alive. The patients who do not need ventilation do better statistically.

A higher injury severity score is associated with higher mortality.

References

• Kilic D, Findikcioglu A, Akin S, Akay TH, Kupeli E, Aribogan A, et al. Factors affecting morbidity and mortality in flail chest: comparison of anterior and lateral location. Thorac Cardiovasc Surg. 2011 Feb. 59(1):45-8.
• Gipson CL, Tobias JD. Flail chest in a neonate resulting from nonaccidental trauma. South Med J. 2006 May. 99(5):536-8
• Tanaka H, Tajimi K, Endoh Y, Kobayashi K. Pneumatic stabilization for flail chest injury: an 11-year study. Surg Today. 2001. 31(1):12-7.
• Pettiford BL, Luketich JD, Landreneau RJ. The management of flail chest. Thorac Surg Clin. 2007 Feb. 17(1):25-33
• Lafferty PM, Anavian J, Will RE, Cole PA. Operative treatment of chest wall injuries: indications, technique, and outcomes. J Bone Joint Surg Am. 2011 Jan 5. 93(1):97-110.