Blunt Chest Trauma

Blunt chest trauma is a non-penetrating traumatic injury to the thoracic cavity. Thoracic traumatic injuries are classified according to the mechanism of injury as blunt or penetrating injuries. Different structures can be injured including the chest wall (ribs, sternum), lungs, heart, major blood vessels, and the esophagus. The extent and specific type of thoracic traumatic injury can be identified by a proper history and physical examination supported by adequate imaging studies. Management depends on the specific type of injury.

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Overview

Definition

Blunt chest trauma is injury and consequential pathology arising from application of significant kinetic forces to the chest that do not cause penetration of the thoracic cavity.

Epidemiology

  • United States incidence: 12:1,000,000 each day
    • 33% require hospital admission.
    • Responsible for 20%–25% of all deaths (from motor vehicle collisions)
  • Risk factors associated with a poor outcome:
    • Older age
    • Higher injury severity scores (ISS)

Etiology

  • Motor vehicle accidents are the most common cause (80%).
  • Other common causes:
    • Falls
    • Vehicles striking pedestrians
    • Acts of violence
    • Blast injuries

Classification

  • Direct blunt force: object striking the chest wall (e.g., fist or bat in assault)
  • Acceleration or deceleration: rapid changes in kinetic energy (e.g., car stopping rapidly)
  • Shear force: forces pushing different parts of the body in opposing directions, often a combination of acceleration and deceleration (e.g., a head-on collision of 2 moving cars)
  • Compression: crush injury (e.g., heavy object falling on a person)
  • Blasts: transfer of energy into chest tissue from concussive wave (e.g., close explosion)

Pathophysiology

The chest wall is composed of:

  • Bone: ribs and intercostal cartilage
  • Musculature: intercostal and pectoral muscle groups
  • Neurovasculature: intercostal nerves, arteries, and veins 
  • Connective tissues: visceral and parietal pleura

The chest wall’s function is to absorb trauma and protect underlying vulnerable structures from damage:

  • Chest wall structures: 
    • Fractures of ribs, clavicles, or cartilage
    • Ecchymosis, laceration, or crush injury of musculature and skin
    • Accumulation of blood or air in the potential pleural space
  • Underlying structures: 
    • Injury to the aorta and other major blood vessels
    • Bruising of the lungs
    • Bruising/laceration of the heart

Initial Approach to the Trauma Patient

Physical exam

The suspected mechanism of injury should prompt suspicion for blunt chest trauma. Treatment algorithms and guidelines direct evaluation:

  • Primary survey—airway, breathing, and circulation (ABC):
    • Airway:
      • Look for foreign objects blocking airway (loose teeth are common foreign bodies in high-force trauma).
      • Assess for injury to the trachea (tracheal injury means intubation will be complex).
      • Listen for unusual breathing sounds (stridor suggests narrowing by a foreign body or edema).
    • Breathing:
      • Look at chest wall movement for even and spontaneous breathing (uneven chest movement suggests “flail chest”).
      • Listen to breath sounds (muffled or uneven may suggest pneumothorax or hemothorax).
    • Circulation:
      • Palpate pulses on all 4 extremities (tachycardia suggests hemodynamic instability or pneumothorax).
      • Assess capillary refill on extremities.
  • Secondary survey:
    • Mechanism of injury:
      • Helps determine severity of injury
      • May indicate what chest structures are injured
    • Close inspection of the chest wall: Seatbelt or steering wheel imprint suggests severe injury.

Imaging

While the initial approach to stabilizing a patient with chest trauma is standardized, further imaging and testing is dependent on the injury discovered during the initial assessment.

Choosing the best imaging studies depends on the patient’s hemodynamic stability:

  • Chest X-ray and focused assessment with sonography in trauma (FAST) → initial diagnostic studies
  • Only stable patients can undergo a computed tomography (CT) scan.
  • Unstable patients → emergent surgery must be considered

Injury to the Chest Wall

Rib fracture

  • Clinical features:
    • Pain is localized and reproducible by taking a deep breath.
    • Location of pain points to possible further underlying injury:
      • 1st rib: possible trauma of lung apices, subclavian vessels
      • 2nd rib: possible ascending aorta, superior vena cava trauma
      • 10th rib: possible diaphragmatic, liver, splenic injury
      • 11th rib: possible diaphragmatic, liver, splenic injury
      • 12th rib: possible renal injury
  • Physical exam findings:
    • Point tenderness to palpation
    • Possible visible bruising or deformity
    • Crepitus may be audible.
  • Imaging:
    • X-ray (appropriate for stable patients):
      • Posteroanterior (PA) chest X-ray 
      • Poor sensitivity, but useful to identify associated pneumothorax, hemothorax, pulmonary contusion
    • CT scan (suggested for more severe injury):
      • Usually not performed if only rib fracture is suspected
      • Higher sensitivity
      • Useful for more detailed anatomy
    • Ultrasound:
      • Less commonly used
      • Useful in detailing extent of associated pneumothorax, hemothorax, pulmonary contusion
  • Management:
    • Pain control: 
      • Allows patients to take deep breaths, decreases associated pneumonia
      • Nerve blocks, opioids, or non-steroidal anti-inflammatory drug (NSAID) choice based on severity of pain
    • Respiratory therapy: incentive spirometry
    • Surgical fixation:
      • Rarely necessary with a simple fracture
      • Performed when there is associated chest wall deformity, flail chest, or symptomatic non-union

Flail chest

  • Clinical features:
    • Tachypnea
    • Tachycardia
    • Hypoxia
  • Physical exam findings:
    • Similar finding to simple rib fractures
    • 3 or more adjacent ribs are each fractured in 2 places.
    • Segment of thoracic wall moves opposite to the rest during breathing (paradoxic movement).
  • Imaging: 
    • X-ray may show multiple rib fractures.
    • CT is usually employed for better anatomic detail.
  • Management:
    • Supplemental oxygen
    • Pain control
    • Positive pressure ventilation (PPV) for respiratory failure

Flail chest: fractured ribs that move paradoxically in comparison to the chest wall

Image by Lecturio.

Clavicle fracture

  • Clinical features:
    • Localized pain to palpation
    • Pain on rotation of shoulder
    • Sensation of cracking/popping with movement 
  • Physical exam findings:
    • Visible localized deformity or swelling 
    • Palpable crepitus
    • Localized pain to palpation
  • Imaging: X-ray is sufficient to define the location and severity of injury.
  • Management:
    • Pain management/icing
    • Immobilization with brace restricting shoulder motion to < 30° of abduction, forward flexion, or extension
    • Indications for surgery include:
      • Open fracture
      • Bone displacement
      • Neurovascular injury
      • Skin tenting

Sternal fractures

  • Clinical features:
    • Localized pain to sternum
    • Very strong forces necessary, so usually associated with other internal injuries
  • Physical exam findings:
    • Pain and tenderness to palpation of sternal area
    • Bony crepitus or deformity
  • Imaging:
    • Ultrasound is used to screen.
    • Chest X-ray has poor sensitivity.
    • CT chest and electrocardiogram (ECG) should be performed for possible associated injuries.
  • Management:
    • Stable patients with isolated sternal fractures: Outpatient management is reasonable.
    • More complex fractures with associated pathology: require surgical consultation for management

Chest CT showing comminuted sternal fracture:
Fractures of the sternum can occur during high-energy chest traumas and can be simple (meaning a single fracture) or comminuted (where the bone breaks into multiple fragments). Usually, fractures of the sternum are associated with underlying injury of the lungs or heart.

Image: “Sternal fracture CT” by Monkhouse SJ, Kelly MD. License: CC BY 2.0

Injury to the Lungs

Pulmonary contusion

  • Clinical features:
    • Develop gradually within 24 hours of trauma
    • Tachypnea, tachycardia, hypoxemia
  • Physical exam findings:
    • Contusion or deformity of the chest wall
    • Lack of chest wall findings does not rule out pulmonary contusion.
  • Imaging:
    • X-ray shows irregular, non-lobular, homogenous opacification of lung fields.
    • May lag behind or not be visible on X-ray
    • CT can provide better anatomic detail.
  • Management:
    • Oxygen
    • Pain control
    • Chest physiotherapy
    • Mechanical ventilation in severe cases

Simple pneumothorax

  • Clinical features:
    • Acute dyspnea
    • Sudden-onset, unilateral (usually) chest pain corresponding to side of collapsed lung
  • Physical exam findings:
    • ↓ Breath sounds
    • Hyper-resonance on percussion
    • ↓ Tactile vocal fremitus
  • Imaging: chest X-ray 
    • Modality of choice
    • Hyperlucency 
    • No tracheal deviation or mediastinal shift
  • Management:
    • Small (≤ 2-cm) stable pneumothoraces:
      • Self-resolve without intervention
      • Support with oxygen as needed.
    • Emergent symptomatic: needle decompression 
    • Symptomatic or small pneumothoraces that fail to self-resolve: chest tube placement

Chest radiograph demonstrating a left pneumothorax:
The green line outlines the pleural line. Notice the lack of bronchovascular markings beyond that line.

Image: “Anteroposterior expired X-ray” by Mikael Häggström, M.D. License: CC0, edited by Lecturio.

Tension pneumothorax

  • Clinical features:
    • Acute dyspnea
    • Sudden-onset, unilateral (usually) chest pain corresponding to side of collapsed lung
  • Physical exam findings:
    • ↓ Breath sounds
    • Hyper-resonance on percussion
    • Mediastinal shift away from tension pneumothorax
    • ↓ Tactile vocal fremitus
    • Jugular venous distention
  • Imaging: chest X-ray
    • Modality of choice
    • Hyperlucency 
    • Tracheal deviation or mediastinal shift away from collapsed lung
  • Management:
    • Emergent needle decompression
    • Thoracostomy tube placement to prevent re-accumulation of air

Tension pneumothorax:
Spontaneous and traumatic pneumothoraces can develop into a tension pneumothorax if the defect that allows air into the pleural space becomes a 1-way valve (air enters during inspiration, but cannot escape during expiration), which causes rising pressure in the pleural cavity, shifting the mediastinum to the contralateral side.

Image by Lecturio.

Hemothorax

  • Clinical features:
    • Chest pain
    • Acute onset dyspnea
  • Physical exam findings:
    • ↓ Breath sounds
    • Dullness on percussion
    • Tracheal deviation, mediastinal shift
    • ↓ Tactile vocal fremitus
    • Signs of hemorrhagic shock in large hemothoraces:
      • Hypotension
      • Tachycardia
      • Tachypnea
      • ↓ Jugular venous pressure
  • Imaging: 
    • Chest X-ray: 
      • Best initial diagnostic study
      • Upright imaging shows layering of blood.
      • Supine imaging shows haziness or opacity (whiteout).
      • May also show free air if pneumothorax is present
    • Ultrasound of lungs:
      • Part of extended focused assessment with sonography in trauma (e-FAST) exam
      • Able to be obtained quickly
      • Can show complex fluid in pleural cavity
      • More sensitive than chest X-ray in detecting hemothorax, but is technician dependent
    • Chest CT definitive imaging choice:
      • Should only be obtained if patient is stable 
      • CT can show other associated pathology.
      • CT angiogram can show the source of bleeding.
  • Management:
    • Chest tube
    • Thoracotomy (if > 1.5 L blood drained directly or continuous high output)

Injury to the Airway

Tracheobronchial tear

  • Clinical features:
    • Airway obstruction causing stridor, marked dyspnea, and respiratory failure
    • Hemoptysis
    • Failure of pneumothorax to resolve even when chest tube is placed (due to continuous air leak)
  • Physical exam findings:
    • Sternal tenderness
    • Subcutaneous emphysema
    • Hamman sign: audible crepitus on cardiac auscultation 
  • Imaging: 
    • Chest X-ray or CT depending on availability 
    • Pneumomediastinum (air trapping in center of chest cavity)
    • Hyoid bone elevation above the 3rd cervical vertebrae
  • Management:
    • Bronchoscopy to evaluate extent of injury
    • Surgical repair even with stable patients given risk for developing airway stenosis

Injury to the Heart

Cardiac tamponade

  • Clinical features:
    • Symptoms of cardiogenic shock
    • Dyspnea and tachypnea
    • Chest discomfort or pressure
  • Physical exam findings:
    • Beck’s triad: 
      • Hypotension
      • ↑ JVP
      • Muffled heart sounds
    • Pulsus paradoxus: disproportionately large drop in systolic blood pressure on inspiration
    • Pericardial rub: audible crescendo-decrescendo extra heart sound, often described as grating noise 
  • Imaging: 
    • Chest X-ray: 
      • Enlarged and globular cardiac silhouette (“water bottle” heart shape)
      • Clear lung fields
    • Echocardiogram: fluid around heart
  • Management: Echocardiography-guided pericardiocentesis is both diagnostic and therapeutic.

Myocardial contusion

  • Clinical features:
    • Associated sternal fracture
    • Symptoms of cardiac failure:
      • Dyspnea
      • Chest pain
  • Physical exam findings: may have signs of congestive heart failure
  • Imaging: FAST 
  • Management:
    • Sustain cerebral perfusion with fluid resuscitation or medication as needed.
    • Needle pericardiocentesis may be helpful when associated with pericardial effusion.

Traumatic cardiac arrest (commotio cordis)

  • Clinical features:
    • Cardiac arrest that occurs in a subsection of predisposed patients when the chest over the heart is struck during a specific portion of the cardiac cycle
    • Clinical history of collapse after chest trauma
    • Absence of history of other cardiac disease
  • ECG:
    • Asystole
    • Ventricular fibrillation
  • Management: Cardiopulmonary resuscitation (CPR) and defibrillation following basic life support (BLS) recommendations

Commotio cordis risk window:
Commotio cordis is a cardiac arrest that occurs when the chest over the heart is struck during the portion of the cardiac cycle corresponding with the upstroke of the T wave on ECG.

Image: “Commotio Cordis” by Agateller. License: Public Domain

Injury to a Blood Vessel

Traumatic aortic rupture

  • Clinical features:
    • Interscapular pain
    • Difficulty breathing
    • Altered mental status
    • Often seen in the setting of a rapid deceleration
  • Physical exam findings:
    • Sign of significant high-force trauma to the chest (e.g., steering wheel imprint)
    • Left-sided subclavicular hematoma
    • New cardiac murmur
  • Imaging:
    • Chest X-ray often obtained per trauma protocol, can show:
      • Mediastinal widening and deviation
      • Distorted aortic arch outline
      • Hemothorax, especially above left lung apex 
    • Chest CT and transesophageal echocardiogram (TEE) are definitive diagnostic modalities.
  • Management:
    • Antihypertensive therapy 
    • Emergent operative repair

Injury to the Esophagus or Diaphragm

Diaphragmatic rupture

  • Clinical features:
    • Respiratory distress 
    • Nausea/vomiting
  • Physical exam findings:
    • Should be suspected based on location of injury → diaphragm reaches up to the 4th intercostal space during exhalation
    • Bowel sounds in chest due to bowel herniation through the diaphragm
    • Decreased lung sounds
    • Dullness on percussion
    • Findings more common on left side (right side is protected by liver)
  • Imaging—found incidentally on X-ray, CT, and ultrasound performed for trauma evaluation:
    • Elevation of hemidiaphragm
    • Small bowel in lungs
  • Management: surgical closure

Diaphragmatic rupture:
Rupture of the diaphragm secondary to chest trauma seen on chest X-ray as bowel contents in the thoracic cavity. Arrow labeled X points to portion of the spleen herniating into the chest cavity through a diaphragmatic rupture.

Image: “Diaphragmatic rupture” by Hariharan D, Singhal R, Kinra S, Chilton A. License: CC BY 2.0

Esophageal rupture

  • Clinical features—no specific findings, but the following have been seen:
    • Chest pain
    • Difficulty swallowing
  • Physical exam findings:
    • Subcutaneous crepitus
    • Neck hematoma
  • Imaging: 
    • Chest X-ray or CT:
      • Pneumomediastinum
      • Pleural effusion
    • Water-soluble contrast esophagography is diagnostic.
  • Management:
    • Antibiotics and supportive care
    • Surgical repair to reduce the risk of significant leakage that can cause a systemic inflammatory response

Differential Diagnosis

  • Flail chest: a condition that occurs when 3 or more contiguous ribs are fractured in 2 or more different locations. Marked by chest pain, tachypnea, hypoxemia, and paradoxic thoracic wall movement. Management includes oxygen supplementation, pain control, and PPV if respiratory failure presents.
  • Hemothorax: a collection of blood in the pleural cavity. Usually occurs following chest trauma, which leads to lung laceration or damage to intercostal arteries. Symptoms include shortness of breath and chest pain. Signs include hypotension, tachycardia, decreased air entry, tracheal deviation, and dullness on percussion. Management is chest tube insertion. Thoracotomy may be indicated.
  • Pulmonary contusion: a traumatic parenchymal lung injury. Patients present with tachypnea, tachycardia, and hypoxemia. Imaging studies show patchy alveolar infiltrates not restricted by anatomic borders (non-lobar opacification). Management involves oxygen administration, pain control, chest physiotherapy, and mechanical ventilation in severe cases.
  • Pneumothorax: an abnormal collection of air in the pleural space. Types of pneumothoraces include simple and tension pneumothorax. Pneumothoraces can be spontaneous, iatrogenic, or traumatic. Exam shows decreased breath sounds, hyper-resonance on percussion, tracheal deviation, mediastinal shift (away from tension pneumothorax), decreased tactile vocal fremitus, and distended jugular veins. Treatment includes needle decompression and thoracotomy.
  • Cardiac tamponade: an accumulation of fluid in the pericardial space, resulting in reduced ventricular filling and subsequent hemodynamic compromise. Cardiac tamponade is a severe form of a pericardial effusion. In a trauma setting, the fluid is blood. Physical examination findings include Beck’s triad (hypotension, jugular venous distention, and muffled heart sounds). Treatment is pericardiocentesis.
  • Aortic dissection: occurs when a fissure develops in the inner coat (tunica intima) of the aortic wall, which causes blood to enter the media layer. Marked by severe pain, characteristically known as a “tearing pain.” Aortic dissection is a serious medical emergency that needs urgent diagnosis and management. Risk factors include hypertension, genetic diseases, and trauma. Treatment starts with blood pressure control and often requires cardiovascular surgery for stenting of the aorta.

References

  1. Legome, E. (2020). Initial evaluation and management of blunt thoracic trauma in adults. UpToDate. Retrieved November 7th, 2020 from https://www.uptodate.com/contents/initial-evaluation-and-management-of-blunt-thoracic-trauma-in-adults
  2. Mancini MC. (2020). Blunt Chest Trauma. In: Blunt Chest Trauma. Emedicine. http://emedicine.medscape.com/article/428723-overview. Retrieved November 22, 2020.
  3. Dogrul BN, Kiliccalan I, Asci ES, Peker SC. (2020). Blunt trauma related chest wall and pulmonary injuries: An overview. Chin J Traumatol 23 (3):125-138.
  4. Beshay M, Mertzlufft F, Kottkamp HW, Reymond M, Schmid RA, Branscheid D, et al. (2020). Analysis of risk factors in thoracic trauma patients with a comparison of a modern trauma centre: a mono-centre study. World J Emerg Surg 15 (1):45.
  5. Refaely Y, Koyfman L, Friger M, Ruderman L, Saleh MA, Sahar G, et al. (2018). Clinical Outcome of Urgent Thoracotomy in Patients with Penetrating and Blunt Chest Trauma: A Retrospective Survey. Thorac Cardiovasc Surg 66 (8):686-692.
  6. Rodriguez RM, Hendey GW, Marek G, Dery RA, Bjoring A. (2006). A pilot study to derive clinical variables for selective chest radiography in blunt trauma patients. Ann Emerg Med 47(5):415-8. doi: 10.1016/j.annemergmed.2005.10.001. Epub 2005 Dec 27. PMID: 16631976.

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