Flail Chest

Flail chest is a life-threatening traumatic injury that occurs when 3 or more contiguous ribs are fractured in 2 or more different locations. Patients present with chest pain, tachypnea, hypoxia, and paradoxical chest wall movement. Management includes oxygen supplementation, pain control, ventilation if respiratory failure presents, and possible surgery. Severe traumatic intrathoracic injuries, such as pulmonary contusions, pneumothorax, and cardiac injuries, are often seen in conjunction with flail chest.

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Flail chest is defined as 3 or more contiguous ribs that are fractured in 2 or more different locations, resulting in a freely moving segment of the chest wall that is discontinuous from the rest of the thoracic cage.


  • Seen in 7% of all chest trauma
  • 60% of cases are associated with other injury (most commonly hemothorax, pneumothorax, or head trauma)
  • Risk factors:
    • Male gender
    • Intoxication


  • Motor vehicle accidents (approximately 75%)
  • Falls, particularly in the elderly (approximately 15%)
  • Blunt trauma


  • Significant traumatic force is applied to the chest wall, creating multiple rib fractures.
  • Disruption of structural components of the chest wall (e.g., bone, cartilage, muscle) leads to free-floating segment of chest.
  • During respiratory cycle, segments move paradoxically:
    • During inspiration, segment moves inward (instead of outward) due to negative intrathoracic pressure → leading to ineffective ventilation → hypoxia
    • During expiration, segment moves outward (instead of inward) due to positive intrathoracic pressure.
  • Mechanical limitation of chest wall motion affects the size of changes in thoracic volume and patient-generated tidal volume → respiratory insufficiency
Flail chest

Flail chest
Multiple rib fractures and disruption of structural components of the chest wall (i.e., bone, cartilage, muscle) leading to a free-floating segment of the chest. The separated segment moves opposite to the rest of the chest wall during the breath cycle (paradoxical movement), creating ineffective ventilation.

Image by Lecturio.


Flail chest is a clinical diagnosis (confirmed by imaging) made by identifying the paradoxical movement of a chest wall segment when the patient is spontaneously breathing. 


  • Severe chest pain
  • Shortness of breath


  • Paradoxical chest wall movement (disappears after intubation with positive pressure ventilation)
  • Respiratory distress
  • Tachypnea
  • Hypoxemia
  • ↓ breath sounds during auscultation
  • Chest wall deformity and/or ecchymosis


  • Chest X-ray (less sensitive, but usually sufficient to confirm clinical suspicion) 
  • CT scan (most sensitive)
  • Findings include:
    • Multiple adjacent rib fractures
    • Fractures 1 + location

Management and Complications


  • Oxygen supplementation
  • Adequate pain control:
    • Pain impairs respiratory effort → hypoventilation, atelectasis, pneumonia, and respiratory failure
    • Epidural infusion: preferred method for extensive rib fractures
    • Intercostal nerve blocks also used
  • Intubation with mechanical positive pressure ventilation if respiratory failure presents (improves ventilation and ↓ paradoxical movement)
  • Chest physiotherapy
  • Monitor with serial chest X-rays, arterial blood gasses, pulse oximetry, and capnography (to detect early signs of respiratory failure).
  • Treat associated conditions.
  • Surgical fixation of ribs (not often used)



  • Collapsed lung
  • Signs and symptoms:
    • ↓ breath sounds on ipsilateral chest
    • Hyperresonance on percussion
  • Management:
    • Supplemental oxygen
    • Possible chest tube (large pneumothoraces)

Tension pneumothorax:

  • Pneumothorax that is under pressure
  • Signs and symptoms:
    • Tracheal deviation → mediastinal shift away from tension pneumothorax
    • Distended neck veins
  • Management: emergent needle decompression → chest tube placement


  • Blood in chest cavity leading to lung compression
  • Signs and symptoms:
    • ↓ breath sounds
    • Dullness on percussion
    • Tracheal deviation, mediastinal shift
    • ↓ tactile vocal fremitus
    • ↓ jugular venous pressure
  • Management: 
    • Chest tube
    • Thoracotomy (if > 1.5 L blood drained directly or continuous high output)

Pulmonary contusion:

  • Bruised lung
  • Signs and symptoms:
    • Onset < 24 hours after blunt thoracic trauma
    • Tachypnea, tachycardia, hypoxemia
    • Imaging shows patchy alveolar infiltrates not restricted by anatomical borders (non-lobar pacification).
  • Management:
    • Oxygen
    • Pain control, chest physiotherapy, mechanical ventilation in severe cases

Acute respiratory distress syndrome (ARDS):

  • Diffuse inflammation of lung parenchyma due to different etiologies
    • Sepsis
    • Acute pancreatitis
    • Massive transfusion
    • Trauma
  • Signs and symptoms:
    • New worsening respiratory condition, usually after 24 hours of insult 
    • Imaging shows bilateral, patchy alveolar infiltrates (pulmonary edema).
    • Hypoxemia with PaO2/FiO2 ratio < 300 mm Hg
  • Management: mechanical ventilation


  • Infection of lung parenchyma often due to hypoventilation, usually polymicrobial
  • Signs and symptoms:
    • Hypoxia
    • Tachypnea
    • Fever
  • Management: broad-spectrum antibiotics

Blunt cardiac contusion:

  • Injury to cardiac muscle due to trauma often associated with sternal fracture
  • Signs and symptoms:
    • New electrocardiogram (ECG) findings (arrhythmias)
    • ↑ cardiac enzymes (troponin) 
  • Management: Treat complications (arrhythmias).

Differential Diagnosis

  • Pulmonary contusion: parenchymal lung injury and accumulation of blood within the lung tissue after chest trauma. Patients present with tachypnea, tachycardia, and hypoxemia. Imaging shows patchy alveolar infiltrates not restricted by anatomical borders. Management involves oxygen administration, pain control, chest physiotherapy, and mechanical ventilation in severe cases.
  • Pneumothorax: abnormal collection of air in pleural space due to laceration of lungs. Types of pneumothorax include simple (spontaneous) and tension pneumothorax. Exam findings include decreased breath sounds, hyperresonance on percussion, and tracheal deviation away from tension pneumothorax. Treatment includes needle decompression and chest tube placement.
  • Hemothorax: collection of blood in pleural cavity. Usually occurs following lung laceration or damage to intercostal arteries. Patients present with shortness of breath and chest pain. Exam findings include tachycardia, tracheal deviation, and dullness on percussion. Management is with chest tube insertion and thoracotomy if > 1.5 L of blood directly evacuated or collecting of > 1 L of blood over 4 hours.
  • ARDS: severe inflammatory reaction of the lung that is characterized by pulmonary infiltrates due to alveolar fluid accumulation, not in cardiogenic etiology. Patients present in respiratory failure. Chest X-ray shows diffuse bilateral lung infiltrates. Management depends mainly on treating underlying etiology and maintaining adequate oxygenation, which usually requires mechanical ventilation.


  1. Legome, E. (2020). Initial evaluation and management of blunt thoracic trauma in adults. UpToDate. Retrieved December 12, 2020, from https://www.uptodate.com/contents/initial-evaluation-and-management-of-blunt-thoracic-trauma-in-adults?search=Flail%20chest&source=search_result&selectedTitle=1~30&usage_type=default&display_rank=1
  2. Sarani, B. (2020). Inpatient management of traumatic rib fractures. UpToDate. Retrieved December 12, 2020, from https://www.uptodate.com/contents/inpatient-management-of-traumatic-rib-fractures?search=Flail%20chest&source=search_result&selectedTitle=2~30&usage_type=default&display_rank=2 
  3. Liman ST, Kuzucu A, Tastepe AI, et al. (2003). Chest injury due to blunt trauma. Eur J Cardiothorac Surg, 2003(23), 374.
  4. Kilic D, Findikcioglu A, Akin S, et al. (2011). Factors affecting morbidity and mortality in flail chest: comparison of anterior and lateral location. Thorac Cardiovasc Surg. 59(1), 45–8.
  5. Sangster GP, Gonzalez-Beicos A, Carbo AI, et al. (2007) Blunt traumatic injuries of the lung parenchyma, pleura, thoracic wall, and intrathoracic airways: multidetector computer tomography imaging findings. Emerg Radiol. 14(5), 297–310. 
  6. Dehghan N, de Mestral C, McKee MD, Schemitsch EH, Nathens A. (2014). Flail chest injuries: a review of outcomes and treatment practices from the National Trauma Data Bank. J Trauma Acute Care Surg. 276(2), 462–8.

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