Basics
Description
- Free-floating segment of chest wall:
- 3 or more adjacent ribs are fractured in 2 or more places.
- Rib fractures in conjunction with sternal fractures or costochondral separations
- The free-floating segment of chest wall paradoxically moves inward during inspiration and outward during expiration.
- The principal pathology associated with flail chest is the associated pulmonary contusion:
- There is no alteration in ventilatory mechanics owing to the free-floating segment.
Etiology
- Blunt thoracic trauma
- Fall from a height
- Motor vehicle accident
- Assault
- Missile injury
- Ribs usually break at the point of impact or posterior angle:
- Ribs 4-9 most prone to fracture.
- Weakest point of ribs is 60 ° rotation from sternum.
- Transfer of kinetic energy to the lung parenchyma adjacent to the injury:
- Disruption of the alveolocapillary membrane and development of pulmonary contusion
- Arteriovenous shunting
- Ventilation/perfusion mismatch
- Hypoxemia
- Respiratory failure may result.
- Relatively elastic chest wall makes rib fractures less common in children.
- Presence of rib fractures implies much higher energy absorption.
Much more susceptible to rib fractures:
- Described with low-energy mechanisms
- Complicated by osteoporosis
Diagnosis
Signs and Symptoms
History
- Blunt thoracic trauma by any mechanism
- Mechanism as described by patient, parent, or pre-hospital personnel:
- Seat belt usage
- Steering wheel damage
- Air bag deployment
- Localized chest wall pain increases with deep inspiration, coughing, moving
- Pleuritic chest pain
- Dyspnea
- Hemoptysis
Physical Exam
- Flail chest paradoxically moves inward during inspiration and outward during expiration:
- Can be missed due to muscle spasm and splinting respirations.
- Inspection under tangential light may be useful.
- Multiple rib fractures:
- Bony step-offs
- Ecchymosis
- Crepitus
- Edema
- Erythema and tenderness associated with:
- Splinting respirations
- Intercostal muscle spasm
- Dyspnea, tachypnea
- Onset may be insidious, increasing over time.
- Cyanosis, tachycardia, hypotension
- Auscultation with initially normal breath sounds progressing to wet rales or absent breath sounds
Essential Workup
Diagnosis is initially made on clinical grounds and then supported by radiographs.
Diagnosis Tests & Interpretation
Lab
Arterial blood gas analysis:
- May reveal hypoxemia
- Elevated alveolar-arterial gradient
Imaging
- Chest radiograph aids diagnosis and prognosis:
- May reveal associated intrathoracic pathology:
- Pneumothorax
- Hemothorax
- Pneumomediastinum
- Pulmonary contusion
- Widened mediastinal silhouette
- Pulmonary contusion appears within 6-12 hr after injury:
- Ranges from patchy alveolar infiltrates to frank consolidation
- Thoracic CT is useful in detecting associated intrathoracic injuries not identified on chest radiograph:
- Thoracic CT found to show on average of 3 additional rib fractures compared with plain chest radiographs.
Differential Diagnosis
- Chest wall contusion or intercostal muscle strain
- Costochondral separation
- Sternal fracture and dislocation
- Radiographic differential diagnosis includes:
- ARDS
- Pulmonary laceration, infarction, or embolism
- CHF
- Pneumonia, abscess, other infectious processes
- Noncardiogenic causes of pulmonary edema
Treatment
Pre-Hospital
- Positioning the patient with the injured side down can stabilize the involved chest wall:
- Improve ventilation in noninjured hemithorax.
- Thoracic trauma with significant mechanism or combined with pre-existing pulmonary disease should be routed to the nearest trauma center.
Initial Stabilization/Therapy
- Manage airway and resuscitate as indicated.
- IV line, O2, continuous cardiac monitoring, and pulse oximetry
- Control airway:
- Endotracheal intubation
- Indicated for patients with severe hypoxemia (PaO2 <60 mm Hg on room air, <80 mm Hg on 100% O2)
- Significant underlying lung disease
- Impending respiratory failure
Ed Treatment/Procedures
- Maintain adequate oxygenation and ventilation.
- Monitor O2 saturation and respiratory rate.
- In conscious and alert patients, O2 administration via face mask is first-line therapy.
- If patient cannot maintain a PaO2 >80 mm Hg on high-flow oxygen, consider continuous positive airway pressure via mask or nasal bilevel positive airway pressure.
- Consider early endotracheal intubation and mechanical ventilation if the above fails:
- Physiologic internal fixation of the flail segment
- External fixation or stabilization of the flail segment is not indicated.
- Adequate pain control is critical to maintaining adequate pulmonary function:
- Avoid splinting, atelectasis, and pneumonia.
- Search for associated injuries and treat exacerbation of underlying lung disease.
- Intercostal nerve blocks with 0.5% bupivacaine are safe and effective when performed properly:
- Provides 6-12 hr of pain relief
- Perform intercostal nerve block posteriorly 2-3 fingerbreadths from the vertebral midline.
- Inject 0.5-1 mL just under the inferior surface of the rib where the neurovascular bundle is located.
- Aspirate 1st to be certain that the intercostal vessels have not been punctured.
- Prophylactic antibiotics are not indicated.
Avoid overhydration:
- In the setting of pulmonary contusion, the need for IV crystalloid resuscitation must be weighed against the risk of increasing interstitial pulmonary edema.
Medication
- Multiple acetaminophen/opioid analgesic combinations are available; see the alert below.
- Acetaminophen: 300 mg/codeine 30 mg (peds: 0.5-1 mg/kg codeine) PO q4-6h
- Acetaminophen: 500 mg/hydrocodone 5 mg PO q4-6h
- Acetaminophen: 750 mg/hydrocodone 7.5 mg PO q4-6h
- Acetaminophen: 325 mg/hydrocodone 10 mg PO q4-6h
- Acetaminophen: 325 mg/oxycodone 5 mg PO q6h
- Bupivacaine: 0.5% 0.5-1 mL per injection for intercostal nerve blocks
- Hydromorphone: 2-8 mg (peds: 0.03-0.08 mg/kg) PO q4-6h
- Hydromorphone: 1-4 mg (peds: 0.015 mg/kg) IV/IM/SC q4-6h
- Morphine sulfate: 0.05-0.1 mg/kg IV/IM/SC q2-6h
- Patient-controlled analgesia using fentanyl, hydromorphone, or morphine sulfate is effective.
- Consider thoracic epidural analgesia for patients with intractable pain, oversedation, or hypoventilation secondary to opioid analgesics.
- NSAIDs discouraged due to the risk of GI bleeding.
- The dose of acetaminophen/opioid analgesic combinations is limited by the hepatic toxicity of acetaminophen.
- The max. acetaminophen dose is 1 g per dose and 4 g/d (peds: 15 mg/kg per dose, do not exceed 5 doses/24 hr)
Follow-Up
Disposition
Admission Criteria
All patients with flail chest should be admitted to critical care setting for close monitoring and adequate pain control.
Discharge Criteria
Patients found to have flail chest, with or without pulmonary contusion, should not be discharged.
Pearls and Pitfalls
- Early pain control is key.
- Beware of concomitant injuries such as pulmonary contusion and pneumothorax.
- Elderly patients have significantly poorer outcomes.
Additional Reading
- Eckstein M, Henderson S. Thoracic trauma. In: Marx J, Hockberger R, Walls R, eds. Rosens Emergency Medicine: Concepts and Clinical Practice, 7th ed. St. Louis, MO: Mosby; 2009.
- Livingston DH, Shogan B, John P, et al. CT diagnosis of rib fractures and the prediction of acute respiratory failure. J Trauma. 2008;64:905-911.
- Simon B, Ebert J, Bokhari F, et al. Management of pulmonary contusion and flail chest: An Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg. 2012;73(5 suppl 4):S351-S361.
- Wanek S, Mayberry JC. Blunt thoracic trauma: Flail chest, pulmonary contusion, and blast injury. Crit Care Clin. 2004;20(1):71-81.
Codes
ICD9
807.4 Flail chest
ICD10
- S22.5XXA Flail chest, initial encounter for closed fracture
- S22.5XXB Flail chest, initial encounter for open fracture
SNOMED
- 78011002 Flail chest (disorder)
- 311409007 Open flail chest (disorder)
- 311408004 Closed flail chest (disorder)