Flail Chest 

Flail chest is a life-threatening blunt chest injury characterized by paradoxical movement of a segment of the chest wall that becomes detached from the rest of the thoracic cage due to multiple rib fractures.

It represents severe underlying pulmonary injury, often associated with pulmonary contusion and respiratory failure.


Definition

A flail chest occurs when:

  • ≥3 or more consecutive ribs are fractured in ≥2 places
    ➜ creating a free-floating segment of the chest wall that moves paradoxically with respiration.

Alternatively:Sternal fractures with bilateral rib fractures can also produce a flail segment (sternal flail).

Mechanism of Injury

  • Usually caused by high-energy blunt trauma:
    • Motor vehicle accidents (most common)
    • Crush injuries
    • Falls from height
    • Direct blow to the chest

Pathophysiology:

  1. Structural component:
    • Disruption of chest wall integrity → a segment of ribs moves inward during inspiration and outward during expiration (opposite to normal chest wall motion).
  1. Underlying pulmonary component:
    • Almost always accompanied by pulmonary contusion underneath the flail segment → alveolar hemorrhage and edema → V/Q mismatch, hypoxemia, and reduced compliance.

Pathophysiology in Detail

Phase

Event

Result

Inspiration

Negative intrathoracic pressure

Flail segment moves inward → reduces tidal volume and worsens ventilation

Expiration

Positive intrathoracic pressure

Flail segment moves outward → inefficient ventilation, air trapping

Net effect

Paradoxical movement

Ineffective ventilation, increased work of breathing, hypoxemia

Plus pulmonary contusion

Alveolar hemorrhage and edema

Decreased lung compliance and oxygenation

Clinical Features

  • Severe chest pain
  • Dyspnea (shortness of breath)
  • Respiratory distress
  • Cough (sometimes blood-stained sputum)
  • May be associated with shock (due to pain, hypoxia, or hemorrhage)

Signs:

  • Paradoxical chest wall movement:
    • Injured segment moves inward during inspiration, outward during expiration
    • Seen best when the patient is quietly breathing or under mechanical ventilation (may disappear)
  • Chest wall deformity
  • Tenderness and crepitus (fractured ribs)
  • Decreased breath sounds (underlying contusion, pneumothorax, or hemothorax)
  • Subcutaneous emphysema
  • Cyanosis and tachypnea

Associated Injuries:

  • Pulmonary contusion
  • Pneumothorax / Hemothorax
  • Cardiac contusion
  • Spinal or head injury
  • Intra-abdominal injury

Diagnosis

  • Paradoxical motion of the chest wall is diagnostic.
  • However, in unconscious or intubated patients, this may be absent or masked.

Chest X-ray:

  • Multiple rib fractures in two places
  • Possible lung contusion (patchy opacities)
  • Associated pneumothorax or hemothorax
  • Subcutaneous emphysema

CT Chest (Gold Standard):

  • Detects extent of rib fractures and pulmonary contusion
  • Helps assess underlying injuries (major vessels, spine)
  • Guides surgical stabilization planning

Ultrasound (FAST / E-FAST):

  • May show lung sliding absence (pneumothorax)
  • Useful in trauma setting for rapid evaluation

Complications

  • Respiratory failure
  • Hypoxemia
  • Pneumonia (due to poor cough and secretion clearance)
  • ARDS
  • Sepsis
  • Death (mortality 10–20%, up to 30–40% if severe pulmonary contusion)

Management

1. Initial (ATLS Protocol)

  • Airway: Ensure patency
  • Breathing: Provide supplemental O₂
  • Circulation: Manage shock, control bleeding
  • Analgesia: Early and effective pain control is critical

2. Respiratory Support

Stage

Management

Mild flail chest without respiratory failure

Supplemental O₂, aggressive analgesia, physiotherapy

Moderate to severe injury or pulmonary contusion

Noninvasive ventilation (NIV) may be used cautiously if no contraindication

Respiratory failure or severe paradoxical motion

Endotracheal intubation and mechanical ventilation to stabilize the chest wall and improve oxygenation

Indications for Intubation:

  • Respiratory distress (RR >35/min)
  • PaO₂ < 60 mmHg despite O₂ therapy
  • Hypercapnia (PaCO₂ > 50 mmHg)
  • Shock or severe associated injuries
  • GCS < 8

3. Pain Control

Goal: Reduce splinting, improve ventilation, and prevent pneumonia.

Options:

  • Systemic analgesia: IV opioids, NSAIDs (with caution)
  • Regional techniques:
    • Epidural analgesia (best option if no contraindication)
    • Paravertebral block
    • Intercostal nerve blocks
    • Erector spinae plane block (modern alternative)

4. Fluid Management

  • Avoid fluid overload → can worsen pulmonary contusion and edema
  • Maintain adequate perfusion using judicious crystalloids and vasopressors if needed.

5. Chest Physiotherapy

  • Deep breathing exercises, incentive spirometry, and early mobilization once stable.

6. Surgical Stabilization (Rib Fixation)

Indications:

  • Flail chest with severe paradoxical motion
  • Failure to wean from ventilator
  • Severe displacement of rib fractures
  • Severe pain not responding to conservative therapy
  • Thoracotomy for other indication (repair of lung or vessel)

Benefits:

  • Reduces duration of ventilation
  • Decreases pneumonia and ICU stay
  • Improves long-term pulmonary function

Prognosis

  • Mortality: 10–20%
  • Dependent on severity of underlying pulmonary injury rather than rib fractures alone.
  • Early pain control, ventilatory support, and pulmonary hygiene are key determinants of outcome.