Flail Chest 

Flail Chest – 9 Interesting Facts

1. Flail chest is defined as 3 or more contiguous rib fractures in 2 or more locations that create a mechanically unstable flail segment and is frequently associated with pulmonary contusions
2. Flail chest occurs in the setting of blunt trauma and is found in approximately 8% of patients admitted to the hospital with rib fractures
3. Respiratory insufficiency and clinical decompensation are due to pain from the rib fractures as well as the pathophysiology caused by underlying pulmonary contusion²
4. Patients should be evaluated and treated according to appropriate trauma protocols with priority given to airway, breathing, circulation, disability, and exposure
5. Flail chest is primarily a clinical diagnosis and may be confirmed with radiograph or CT imaging; ultrasound may be used in resource-limited settings
6. Emergent treatment includes escalating respiratory support, multimodal pain management and judicious fluid resuscitation
7. Open surgical fixation of the flail segment provides definitive management and is currently recommended in specific populations; this is an area of active research
8. Patients with flail chest require admission to a hospital with appropriate resources for full-spectrum trauma care; transfer should be arranged as soon as the need for a higher level of care is recognized and should not be delayed for definitive diagnosis
9. A diagnosis of flail chest conveys significant morbidity and mortality and may be associated with long-term complications and prolonged recovery time

Alarm Signs and Symptoms

• Respiratory distress
• Hypoxia

Basic Information

Terminology

• Flail chest is defined as 3 or more contiguous rib fractures in 2 or more locations that create a mechanically unstable flail segment, which thereby results in a paradoxical movement while breathing¹
• Pulmonary contusions are an injury to the parenchyma of the lung, often secondary to blunt force trauma and frequently associated with flail chest²

Epidemiology

• Thoracic trauma occurs in approximately 20% of major trauma¹
• Thoracic trauma and subsequent complications are responsible for 25% of traumatic deaths¹
• Flail chest occurs in approximately 8% of patients with rib fractures admitted to the hospital³
  • In a patient with 6 rib fractures, the risk of flail chest is approximately 4%⁴
  • In a patient with 8 or more rib fractures, the risk increases to approximately 6.4%⁴

Etiology and Risk Factors

Etiology

• Significant blunt force causes contiguous ribs to fracture at multiple sites creating the flail segment
  • Generally caused by motor vehicle crash, fall from height, or direct blow to the thorax³
• Respiratory insufficiency and clinical decompensation are the result of pain from the rib fractures as well as the pathophysiology caused by the associated underlying pulmonary contusion²
  • Shallow respirations secondary to pain result in collapse of alveoli, arteriovenous shunting, and hypoxemia³
  • Parenchymal injury causes edema and necrosis within the lung tissue impairing gas exchange⁵

Risk Factors

• Metabolic bone disease
• Osteogenesis imperfecta
• Advanced age

Diagnosis

Approach to Diagnosis

• Flail chest is generally secondary to major trauma; thus, the approach to diagnosis and evaluation should follow standard trauma protocol
  • Use the ATLS⁶ protocol (Advanced Trauma Life Support): airway, breathing, circulation, disability, and exposure
  • Note that in concordance with ATLS guidelines, obtaining history, imaging, and definitive diagnoses should not delay lifesaving interventions⁶
  • Bedside eFAST examination (extended Focused Assessment with Sonography in Trauma) may help identify a clinically significant hemothorax/pneumothorax associated with a flail chest
• Imaging modalities, such as chest radiographs and CT, may confirm diagnosis and evaluate for associated injuries

Workup

History

• Obtain the patient’s history, including mechanism of injury and initial resuscitative efforts by emergency medical services
  • History may be provided by the patient if mental status allows
  • Supplemental history from bystanders or law enforcement may also be useful in determining the mechanism of injury
  • Targeted history taking should not preclude proceeding with the ATLS trauma survey (Advanced Trauma Life Support)⁶
    • If multiple team members are available, history taking may occur concurrently with the primary and secondary surveys
    • Mnemonic “AMPLE” may be useful in obtaining an initial targeted history
      • Allergies
      • Medications
      • Past medical/surgical history
      • Last meal
      • Events/environment leading to injury

Physical Examination

• Follow trauma protocols for a comprehensive trauma examination⁶
• Flail chest
  • Vital sign derangements may include tachypnea and tachycardia⁷
  • General respiratory distress or increased work of breathing may be apparent
  • Adequately expose and examine the chest wall
    • Assess for pain and tenderness to focal areas of chest wall injury
    • Crepitus may be appreciated
    • A flail segment may be visualized moving in an opposite direction from the rest of the thorax during respiration (eg, paradoxical movement)
      • Note that visualization of paradoxical movement may be difficult in some of the following situations:
        • Intubation and positive pressure ventilation (cause internal splinting of the chest wall)
        • Shallow breathing
        • Large body habitus
  • Complete bedside eFAST examination (extended Focused Assessment with Sonography in Trauma) to evaluate for hemothorax or pneumothorax

Laboratory Tests

• Laboratory studies, including a CBC and CMP (comprehensive metabolic panel), are indicated for most patients presenting with suspected thoracic trauma
  • In patients with abnormal vital signs, blood gas and serum lactate may help guide resuscitation
  • Obtain blood type and screen and coagulation studies (PT [prothrombin time]/INR and PTT [partial thromboplastin time]) in any patient with suspected clinically significant bleeding or coagulopathy
  • Troponin
    • Current trauma guidelines recommend use of troponin I and ECG for evaluation of blunt cardiac injury in patients with significant mechanism of injury and those who respond poorly to resuscitative efforts⁸
  • Further laboratory studies should be guided by clinical presentation and institution-specific trauma protocols

Imaging Studies

• Chest radiograph should be the initial study to evaluate for flail chest⁹
  • Chest radiograph is not sensitive (40% sensitivity/specificity 99%)⁹ and may miss multiple rib fractures that can be identified by CT¹¹
  • Dedicated rib series radiography improves sensitivity, but may still miss one-fourth of the rib fractures¹¹
• CT scan
  • Gold standard for evaluation of severe thoracic trauma¹²
  • Provides high sensitivity and specificity for both bony injury and underlying traumatic thoracic injuries (eg, pulmonary contusions, hemothorax/pneumothorax)¹²
• Chest ultrasonography¹⁴
  • Recent meta-analysis showed that chest ultrasonography (including both bedside emergency department studies and formal radiology department studies) is both sensitive (89.3%) and specific (98.4%) for diagnosis of rib fracture¹⁴
  • Particularly useful in resource-limited settings without CT readily available

Diagnostic Studies

• ECG
  • Obtain a 12-lead ECG in patients with significant mechanism and/or concern for blunt cardiac injury⁸

Differential Diagnosis

Table 1. Differential Diagnosis: Flail chest.

Condition	Description	Differentiated by
Bronchial injury	Rare, life-threatening injury in which air leaks from bronchial tree to surrounding structures	Pneumomediastinum and pneumothorax that are refractory to adequate chest tube placement
Diaphragmatic trauma	Herniation of abdominal contents into the thoracic cavity	Bowel sounds within the chest; imaging shows bowel or other abdominal organs within the chest
Hemothorax/pneumothorax	Collection of blood/air in the pleural space	Imaging shows findings of air/blood products within the chest cavity
Pneumomediastinum	Air within the mediastinum due to air leak	Imaging shows air in the mediastinum
Pulmonary contusion	Injury to the lung parenchyma without laceration to the lung or vascular structures	Imaging findings range from ground glass (mild contusions) to widespread consolidation similar to those of pneumonia (in severe contusions)
Aortic transection	Near complete tear of the aorta due to the fixed nature of the aorta from blunt trauma	Chest radiograph may show a widened mediastinum and CT may show a transection of the aorta
Clavicular fracture	Fracture of the clavicle	Physical examination findings of clavicular deformity and/or focal tenderness; imaging confirms clavicular fracture
Sternal fracture	Fracture of the sternum	Physical examination findings of sternal deformity and/or focal tenderness; imaging confirms sternal fracture

Treatment

Approach to Treatment

• Address traumatic injuries emergently with a focus on immediate, life-threatening injuries
  • Patients may decompensate at any time and appropriate interventions should be made as indicated
  • Change in clinical condition merits reevaluation and repeat imaging
• Respiratory compromise in patients with flail chest is due to both pain-induced shallow respirations and the underlying pulmonary contusion, rather than the paradoxical movement of the chest wall itself¹⁵
  • Initial treatment includes escalating respiratory support, analgesia, and judicious fluid resuscitation
• Surgical fixation may be considered
• Admission to a trauma center is indicated in all patients with flail chest

Nondrug and Supportive Care

• Respiratory support
  • Monitor respiratory status with continuous pulse oximetry and end-tidal capnography (if available)
  • Administer supplemental oxygen
  • Patients may fatigue quickly due to increased work of breathing and hypoxemia
  • Escalation of respiratory support should proceed as indicated by ongoing monitoring of clinical status
    • Mechanical ventilation for the purpose of managing chest wall instability is not obligatory¹⁶
    • Trial of noninvasive CPAP is recommended before intubation¹⁶
      • Monitor clinical status and blood gas to determine response
      • Contraindications include facial trauma, inability to protect airway, and active emesis
    • Consider early intubation for the following indications:¹⁷
      • Shock
      • Severe head injury
      • Comorbid pulmonary disease (eg, chronic obstructive pulmonary disease)
      • Fracture of 8 or more ribs
      • Age older than 65 years
      • Arterial PO₂ less than 80 mm Hg despite supplemental oxygen
    • Emergent intubation is indicated for respiratory arrest, failure of CPAP trial, or decompensation indicative of impending respiratory arrest
  • Splinting of the flail segment (with positioning or with weight to the affected ribs) is no longer used¹⁸
    • These interventions decrease chest wall expansion and cause an increase in the amount of atelectasis
• Fluid administration
  • Avoid unnecessary fluid administration; a pulmonary artery catheter may be useful to avoid fluid overload¹⁶

Drug Therapy

• Multimodal pain management is recommended¹⁹
  • Narcotic analgesics¹⁹
    • Intermittent dosing or continuous infusion via patient-controlled analgesia
    • Options include fentanyl, morphine sulfate, and hydromorphone
    • Improve pain scores and vital capacity
    • May cause sedation, cough suppression, respiratory depression, and hypoxemia
  • Non-narcotic analgesics
    • NSAIDS such as IV ketorolac or oral ibuprofen
    • Acetaminophen IV or oral
    • Low-dose IV ketamine²⁰
      • Can be considered as an adjunct to narcotic pain medications
      • Trials have not shown conclusive benefit²⁰
  • Regional anesthesia¹⁹
    • Epidural anesthesia
      • Trauma guidelines recommend epidural anesthesia as the optimal modality of pain relief for blunt chest/severe blunt thoracic trauma¹⁹
        • Epidural anesthesia improves subjective pain perception and pulmonary function tests in comparison with IV narcotics
        • Epidural anesthesia is associated with less respiratory depression, somnolence, and gastrointestinal symptoms
      • May include narcotics, anesthetic agents, or combinations thereof
      • Catheters placed into the epidural space to deliver agent(s)
    • Other regional anesthesia procedures may be considered but lack substantial evidence in support of their use¹⁹
      • Intercostal nerve block
        • Injection of local anesthetic into the posterior component of the intercostal space
      • Interpleural anesthesia
        • Placement of local anesthetic agent into the pleural space via an indwelling catheter
      • Thoracic paravertebral block
        • Administration of a local anesthetic agent in close proximity to the thoracic vertebrae
  • Topical analgesia
    • Topical lidocaine patches
      • A large retrospective study showed lidocaine patches were associated with decrease in opiate utilization during hospital course in patients admitted with rib fractures²²

Treatment Procedures

• Surgical open fixation of the flail segment
  • Improved outcomes include lower mortality, shorter duration of mechanical ventilation, decreased length of hospital and ICU stay, and lower incidence of pneumonia and need for tracheostomy²³
  • Area of active research with current studies suggesting benefit, but surgical societies are not yet aligned with recommendations
    • Guidelines from the Eastern Association for the Surgery of Trauma recommend ORIF (open reduction and internal fixation) for most trauma patients with flail chest after blunt trauma²³
    • Western Trauma Association guidelines recommend consideration of early rib fixation in patients requiring intensive care without other injuries that that would prolong immobility or intubation (because these may negate the benefit to patients’ overall clinical course)¹⁵
    • Chest Wall Injury Society guidelines recommend surgical stabilization of rib fractures in specific scenarios with indications including 3 or more ipsilateral rib fractures displaced 50% or more of the rib and/or chest wall instability²⁵

Admission Criteria

• Patients with flail chest require admission to a hospital with appropriate resources for full-spectrum trauma care (consideration for early transfer is recommended if presenting facility is not able to render appropriate level of trauma care)

Follow-up

Prognosis and Complications

• Flail chest when associated with other organ injury has a mortality rate of 5% to 10%²⁶
  • Worse outcomes are associated with the following:
    • Advanced age¹⁹
    • Increased Injury Severity Score¹⁶
    • Need for mechanical ventilation¹⁶
• Acute complications may include:
  • Acute respiratory distress syndrome
  • Pneumonia/sepsis
  • Respiratory failure
• Long-term complications may include:
  • Permanent chest wall deformity
  • Persistent dyspnea
  • Persistent chest wall pain
  • Intolerance to exertion
• Recovery of flail chest is prolonged²⁶
  • Most patients take 6 to 12 months for full recovery

References

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