Flail Chest: Symptoms, Types, Causes and Treatment

Flail chest is a life-threatening injury that profoundly affects breathing and overall health following severe chest trauma. Characterized by a segment of the rib cage breaking and becoming detached from the rest of the chest wall, flail chest can rapidly lead to respiratory failure if not recognized and managed promptly. This article explores the symptoms, types, causes, and modern treatment approaches for flail chest, drawing on the latest evidence from trauma centers and surgical studies.

Symptoms of Flail Chest

Recognizing flail chest early is essential for initiating lifesaving interventions. The condition presents with a combination of distinctive symptoms, many of which are directly related to the instability of the chest wall and impaired respiratory function.

Key Symptom	Description	Clinical Impact	Sources
Paradoxical Motion	Segment moves inward on inspiration, outward on exhale	Severe respiratory distress	2 4 7
Chest Pain	Severe, localized pain at injury site	Limits breathing, increases risk of hypoventilation	4 7
Respiratory Distress	Rapid, shallow breathing; use of accessory muscles	May progress to failure	4 7 9
Crepitus	Grating sound/feeling over fractured ribs	Suggests multiple rib fractures	4
Hypoxemia	Low blood oxygen, cyanosis, confusion	May require intubation	4 7 9

Table 1: Key Symptoms

Paradoxical Chest Wall Movement

The hallmark of flail chest is paradoxical motion: during inhalation, the flail segment is drawn inward, and during exhalation, it bulges outward. This is the opposite of normal chest wall movement and results from the segment no longer being structurally connected to the rest of the rib cage. This paradoxical motion not only impairs effective ventilation but also is visually distinctive, aiding in rapid diagnosis at the bedside 2 4 7.

Pain and Respiratory Distress

Patients typically experience severe pain at the site of rib fractures, which can lead to splinting—a tendency to take shallow breaths to minimize discomfort. This, combined with the mechanical dysfunction of the chest wall, results in rapid and shallow breathing, decreased oxygenation, and potentially respiratory failure. The distress may escalate quickly, requiring emergency intervention 4 7 9.

Other Signs: Crepitus and Hypoxemia

Crepitus, a crackling sensation felt or heard over the area, is a sign of underlying rib fractures. In severe cases, hypoxemia or low blood oxygen levels can develop, leading to cyanosis (bluish skin), confusion, or even loss of consciousness if not promptly managed 4 7.

Types of Flail Chest

Not all flail chests are alike. The specific characteristics depend on the number, location, and pattern of rib fractures, as well as the underlying cause.

Type	Description	Typical Location	Sources
Anterolateral	Flail segment on the front/side of chest	Anterolateral ribs	3 5
Posterolateral	Flail segment on the back/side	Posterolateral ribs	3
Bilateral	Involves both sides of chest	Rare, severe cases	1
Iatrogenic	Caused by medical procedures (e.g., CPR)	Variable	5

Table 2: Types of Flail Chest

Anterolateral and Posterolateral Flail Chest

Most commonly, flail segments occur on the anterolateral (front/side) or posterolateral (back/side) aspects of the rib cage, depending on where the trauma occurred. Anterolateral flail chest is frequently seen due to direct blows or crush injuries to the front of the chest 3. Posterolateral flail chest is less common but may occur with high-impact trauma to the back or sides.

Bilateral Flail Chest

Bilateral flail chest, where both sides of the chest wall are involved, is rare and usually results from extremely severe trauma, such as high-speed motor vehicle accidents or heavy object compression. This type is associated with the highest risk of respiratory failure and mortality 1.

Iatrogenic Flail Chest

Flail chest can occasionally result from medical procedures, notably cardiopulmonary resuscitation (CPR), especially in older adults with more brittle ribs. In such cases, multiple contiguous rib fractures can cause a flail segment even without external trauma 5.

Causes of Flail Chest

Understanding the mechanisms that lead to flail chest is crucial for prevention and timely diagnosis. The injury is almost always the result of significant blunt force trauma, but can also arise from certain medical interventions.

Cause Type	Mechanism/Description	Typical Scenario	Sources
Blunt Trauma	Direct impact causing multiple rib fractures	Motor vehicle accidents, falls, crush injuries	1 4 7
Compression Injury	Severe squeezing of chest	Vending machine, building collapse	1
Medical Procedure	Complication from interventions	CPR, thoracic surgery	5
Pathologic	Underlying bone disease (rare)	Osteoporosis, malignancy	5

Table 3: Causes of Flail Chest

Blunt Trauma: The Leading Cause

The vast majority of flail chest cases result from direct blunt trauma, such as those sustained in motor vehicle collisions, falls from height, or assaults. In one hospital study, motor vehicle accidents accounted for over 60% of rib fracture cases, many of which progressed to flail chest if multiple contiguous ribs were broken in more than one place 4 7.

Compression Injuries

Crushing forces, such as those from falling heavy objects (e.g., vending machines, building collapses), can generate enough force to fracture multiple ribs on both sides, resulting in a flail segment. Biomechanical modeling has shown that forces exceeding 2,500 N of static pressure (equivalent to about 260 kg) are required to produce flail chest in a typical adult 1.

Iatrogenic and Pathologic Causes

Flail chest can also occur as a complication of medical procedures, most notably during vigorous CPR in elderly or osteoporotic patients, or after thoracic surgery. Rarely, pathologic fractures from bone-weakening diseases may lead to a flail segment with minimal trauma 5.

Treatment of Flail Chest

Managing flail chest requires a multidisciplinary approach, focusing on stabilizing the chest wall, ensuring adequate oxygenation, managing pain, and preventing complications such as pneumonia or respiratory failure.

Treatment	Purpose/Effect	Outcome Improvement	Sources
Analgesia	Pain control, improve breathing	Reduced pneumonia, improved ventilation	4 7 9
Respiratory Support	Oxygen, ventilation, CPAP/PEEP	Prevent/fix respiratory failure	4 7 9
Surgical Fixation	Stabilize chest wall, repair ribs	Fewer ventilator days, reduced mortality	6 8 10
Chest Tube	Manage pneumothorax/hemothorax	Prevent collapse, improve oxygenation	4 7
Physiotherapy	Mobilize secretions, improve lung expansion	Fewer complications	4 9

Table 4: Main Treatments for Flail Chest

Pain Management and Analgesia

Effective pain control is foundational. Severe pain limits deep breathing and coughing, increasing the risk of pneumonia and respiratory insufficiency. Modern protocols recommend multimodal analgesia, with epidural catheters or paravertebral blocks providing superior pain relief in severe cases 4 7 9. However, these techniques remain underutilized, with large trauma databases showing only 8% of patients receiving epidural analgesia 7.

Respiratory Support: Oxygen, CPAP/PEEP, and Mechanical Ventilation

Supportive respiratory care is tailored to the severity of the injury:

• Oxygen is provided to all patients.
• Non-invasive ventilation (CPAP or PEEP) can stabilize the flail segment in alert, cooperative patients with marginal respiratory status.
• Mechanical ventilation is reserved for those with respiratory failure, severe hypoxemia, or shock. Early weaning is promoted to avoid ventilator-associated complications 7 9.

Surgical Fixation of the Chest Wall

Surgical stabilization has seen a resurgence due to mounting evidence of its benefits. Fixation with plates, screws, or bars (such as the Nuss bar) directly stabilizes the flail segment, restores chest wall integrity, and improves pulmonary function. Meta-analyses and guidelines show that operative fixation:

• Reduces days on mechanical ventilation (mean reduction: 8 days)
• Lowers rates of pneumonia, sepsis, and tracheostomy
• Decreases ICU and hospital length of stay
• Reduces mortality and long-term chest deformity 6 8 10

Surgical fixation is especially valuable for patients who cannot be weaned off the ventilator or have persistent instability despite conservative measures.

Chest Tubes and Management of Complications

Patients frequently develop pneumothorax or hemothorax due to associated lung injuries. Chest tubes are inserted to evacuate air or blood, preventing lung collapse and improving oxygenation 4 7.

Physiotherapy and Multidisciplinary Care

Early and aggressive chest physiotherapy is crucial to prevent complications such as pneumonia. Multidisciplinary protocols involving surgeons, intensivists, respiratory therapists, and physiotherapists improve overall outcomes 4 9.

Conclusion

Flail chest remains a complex and dangerous injury, but advances in evidence-based management have transformed patient outcomes. Key points include:

• Symptoms: Paradoxical chest movement, severe pain, respiratory distress, crepitus, and hypoxemia are classic signs.
• Types: Flail chest is classified by the location and pattern of rib fractures, with anterolateral, posterolateral, bilateral, and iatrogenic forms.
• Causes: Most cases arise from blunt chest trauma or compression, but medical procedures can also be responsible.
• Treatment: Modern care emphasizes robust pain control, tailored respiratory support, early physiotherapy, and, where appropriate, surgical stabilization of the chest wall.

With early recognition and a multidisciplinary approach—including consideration of surgical fixation in select cases—patients with flail chest can achieve improved survival and functional outcomes.