Thoracic Trauma


Chest Wall Injuries

  1. Rib Fractures
    1. Mechanism of Injury
      • fractures of the 1st - 3rd ribs and scapula are often associated with other severe injuries to the head, neck, spinal cord, lungs, and great vessels, and have a 30% mortality rate because of associated injuries
      • fractures of the lower ribs (10 – 12) should increase suspicion for hepatosplenic injury
      • since young patients have a more flexible chest wall, rib fractures suggest a greater transfer of force than in older patients

    2. Diagnosis
      • localized pain, tenderness on palpation, or crepitus are usually present
      • chest x-ray or chest CT should be obtained, primarily to rule out other thoracic injuries
      • special rib films are not necessary

      First Rib Fracture
      First Rib Fracture

    3. Management
      • pain impairs ventilation and cough, which may lead to atelectasis and pneumonia, especially in elderly patients who may have underlying chronic lung disease
      • aggressive pain control without respiratory depression is the key management goal
      • systemic narcotics are usually sufficient for 1 – 2 rib fractures, but more extensive injuries will benefit from epidural anesthesia or rib blocks
      • aggressive pulmonary toilet and chest physical therapy must also be part of the treatment plan

  2. Sternal Fractures
    1. Mechanism of Injury
      • results from high-energy MVAs and falls
      • associated with other serious injuries: cardiac contusion, thoracic aortic rupture

    2. Diagnosis
      • mechanism of injury, as well as sternal pain and crepitus, suggest the injury
      • lateral CXR or chest CT will confirm the diagnosis

      Sternal Fracture
      Sternal Fracture

    3. Management
      • typically nonoperative with pulmonary toilet and analgesia
      • rarely open reduction and internal fixation may be required for significant chest wall instability
      • if the internal mammary artery has been injured then open ligation or embolization may be necessary

Pulmonary Injuries

  1. Simple Pneumothorax
    1. Pathophysiology
      • caused by a lung parenchymal laceration from penetrating trauma or rib fractures
      • air in the pleural space collapses lung tissue
      • ventilation/perfusion mismatch occurs when blood perfusing the nonventilated lung is not oxygenated
      • if unrecognized, can evolve into a life-threatening tension pneumothorax, especially if positive pressure ventilation is applied

    2. Diagnosis
      • breath sounds are decreased on the affected side
      • percussion may demonstrate hyperresonance
      • upright chest x-ray confirms the diagnosis

      Pneumothorax
      Right Pneumothorax

    3. Management
      • chest tube insertion is mandatory for a traumatic pneumothorax visible on CXR
      • if a patient has sustained a significant chest injury, even if a pneumothorax is not present, a chest tube should be inserted prophylactically under the following circumstances:
        • requires transfer by air or ground vehicle
        • requires general anesthesia for treatment of other injuries
        • requires positive pressure ventilation


    4. Management of Occult Pneumothorax
      • defined as a pneumothorax seen on CT but not on CXR
      • most patients can be successfully managed without chest tube placement
      • a small percentage of patients will have progression of the pneumothorax and require a chest tube
      • development of a tension pneumothorax does not appear to be a risk

  2. Hemothorax
    1. Diagnosis
      • in the supine position, the CXR may show only a diffuse haziness

      Hemothorax
      Right Hemothorax

    2. Management
      • any hemothorax sufficient to appear on chest x-ray should be treated with a large-bore chest tube
      • a chest tube provides a way to continuously monitor ongoing blood loss and helps aid in the decision on when to intervene operatively
      • in ~ 85% of cases, bleeding stops spontaneously because it originates from the low pressure pulmonary circuit
      • indications for thoracotomy include initial output > 1500 mL, or persistent drainage of 200 mL/hour for 4 hours
      • bleeding that persists is from the systemic circulation (intercostal, internal mammary arteries), major pulmonary veins, or heart
      • the pleurovac should contain an autotransfusion device so the collected blood can be given back to the patient
      • if a hemothorax is not fully evacuated, an empyema or clotted hemothorax resulting in lung entrapment can result (retained hemothorax)

  3. Pulmonary Contusion
    1. Pathophysiology
      • most common potentially lethal chest injury
      • often associated with a flail chest
      • extensive interstitial and alveolar hemorrhage leads to a ventilation/perfusion mismatch with resulting hypoxemia
      • as pulmonary compliance decreases, the work of breathing increases

    2. Diagnosis
      • chest x-ray shows patchy infiltrates
      • findings may not be initially apparent on x-ray, and may take up to 24 hours to evolve
      • respiratory failure may also take some hours to become manifest, and the severity of the clinical picture may not correlate with the chest x-ray findings

      Pulmonary Contusion
      Right Pulmonary Contusion

    3. Management
      • treatment is supportive and consists of supplemental oxygen, pain control, and pulmonary toilet
      • severely hypoxic patients will require intubation and mechanical ventilation
      • avoid excessive volume expansion, but fluid restriction is not indicated
      • patients are at high risk for ventilator-associated pneumonia
      • contusions usually begin to resolve within 48 - 72 hours

Aortic and Cardiac Injuries

  1. Traumatic Aortic Disruption
    1. Mechanism of Injury
      • caused by abrupt deceleration injuries (high-speed, head-on collisions, falls from significant heights)
      • shear forces act at points of fixation, resulting in transection
      • most common site is the descending aorta just distal to the left subclavian artery at the ligamentum arteriosum, where it is fixed to the thorax
      • majority of patients die at the scene of free perforation and exsanguination
      • survivors have the rupture contained within the adventitia and tissue of the mediastinum, forming a pseudoaneurysm

      Traumatic Aortic Pseudoaneurysm
      Traumatic Aortic Pseudoaneurysm

    2. Diagnosis
      • specific signs and symptoms are usually absent
      • CXR may demonstrate a widened mediastinum, apical capping, loss of the aortic knob, deviation of the left mainstem bronchus, left hemothorax, fracture of the 1st, 2nd ribs, and scapula
      • CXR alone has a high rate of missed injuries
      • spiral (helical) CT is the imaging test of choice based on mechanism of injury or following up a suggestive CXR

      CXR - Widened Mediastinum
      Widened Mediastinum

    3. Management
      • natural history is the slow expansion of the hematoma with eventual rupture
      • emergent bleeding should be addressed first (intra-abdominal, pelvic)
      • beta-blockers (esmolol) reduce aortic wall stress and should be started early, with a goal heart rate < 80 BPM and a MAP of 60 -70 mm Hg
      • endovascular stent graft repair is now the treatment of choice, and may reduce the incidence of paraplegia and mortality
      • when required, open surgical repair is via a left posterolateral thoracotomy

  2. Blunt Cardiac Injury (Cardiac Contusion)
    1. Pathophysiology
      • results from blunt trauma to the chest
      • myocardial contusions may result in arrhythmias, which are usually self-limiting
      • rarely, patients can present with heart failure and cardiogenic shock
      • most common cause of death is ventricular tachycardia or fibrillation

    2. Risk Factors
      • deformed steering wheel
      • precordial bruises or abrasions
      • marked precordial tenderness
      • fractured sternum
      • bilateral rib fractures
      • pulmonary contusion, hemothorax
      • thoracic spine fractures

    3. Diagnosis
      • no universally accepted diagnostic test
      • no correlation between troponin levels and conduction or structural abnormalities
      • chest x-ray is valuable for assessing pulmonary and skeletal injuries, as well as cardiac size
      • EKG is required to diagnose arrhythmias
      • echocardiography is used to evaluate structural abnormalities in unstable patients: wall motion abnormalities, pericardial effusions, valvular insufficiency, chordae tendineae rupture, septal perforations, cardiac chamber rupture

    4. Management
      • if one or more risk factors for blunt cardiac injury are present, then an EKG and chest x-ray should be done
      • if the EKG shows an arrhythmia, then the patient should be admitted to a monitored bed for 24 – 48 hours
      • a cardiology consult should be obtained if the patient has a persistent arrhythmia or an abnormal echocardiogram
      • lethal ventricular arrhythmias require immediate cardioversion

Mediastinal Injuries

  1. Tracheobronchial Tree Injury
    1. Mechanism of Injury
      • rare, usually from a penetrating injury
      • may also occur in high-speed MVAs, with most patients dying at the accident scene
      • most injuries occur within 1-2 cm of the carina

    2. Diagnosis
      • dyspnea, hemoptysis, subcutaneous emphysema, and tension pneumothorax are frequent manifestations
      • chest x-ray may show pneumothorax, pneumomediastinum, and subcutaneous emphysema
      • massive air leak without re-expansion of the lung after chest tube insertion is highly suggestive of a tracheobronchial injury
      • flexible or rigid bronchoscopy confirms the diagnosis

      Extensive Subcutaneous Emphysema
      Extensive Subcutaneous Emphysema

    3. Management
      • airway control may require intubation with fiberoptic guidance
      • multiple chest tubes may be required to reexpand the lung
      • small lacerations may be treated nonoperatively if the lung can be reexpanded
      • larger injuries with require debridement, primary repair or segmental resection with absorbable sutures, and coverage with an intercostal muscle flap
      • most tracheal injuries are best approached with a right posterolateral thoracotomy; distal left-sided injuries must be approached with a left posterolateral thoracotomy

  2. Esophageal Injuries
    1. Mechanism of Injury
      • most commonly results from penetrating trauma with injuries to adjacent structures
      • mortality rate is 39%
      • blunt injury is extremely rare and results from forceful expulsion of gastric contents into the esophagus from a severe blow to the upper abdomen

    2. Diagnosis
      • injury is suspected by the trajectory of the weapon
      • chest x-ray may show pneumomediastinum, pneumothorax, or a left pleural effusion, but it may also be normal
      • chest CT may reveal air adjacent to the esophagus but outside the lumen
      • diagnosis is made by a contrast esophagram and may be followed up with esophagoscopy in indeterminate or negative studies
      • delay in diagnosis is associated with worse outcomes

      Pneumomediastinum
      Pneumomediastinum

    3. Management
      • proximal thoracic esophagus is best approached through a right posterolateral thoracotomy (4th or 5th interspace)
      • distal esophagus is approached through a left posterolateral thoracotomy (6th or 7th interspace)
      • injuries diagnosed early (<24 hours) may be repaired primary, buttressed with a pleural or intercostal muscle flap, and widely drained
      • leaks and fistulas are common
      • gastro-esophageal injuries can be reinforced with a partial fundoplication
      • consider a gastrostomy for decompression and a feeding jejunostomy for nutritional support
      • late injuries, or if mediastinitis is present, are treated with esophageal exclusion (cervical esophagostomy, closure of the G-E junction) and wide mediastinal drainage
      • if inflammation is too severe, then esophagectomy may be the only option

  3. Traversing Mediastinal Wounds
    1. Mechanism of Injury
      • penetrating objects that cross the mediastinum may injure the heart, great vessels, tracheobronchial tree, or esophagus

    2. Diagnosis
      • entrance wound in one hemithorax and exit wound or missile in the contralateral hemithorax
      • high-risk area (‘cardiac box’) is bound by the sternal notch superiorly, costal margin inferiorly, and the nipples laterally

      Cardiac Box
      Cardiac Box

    3. Management
      1. Hemodynamically Unstable Patient
        • has massive thoracic hemorrhage, tension pneumothorax, or pericardial tamponade
        • emergency operative thoracotomy is best approached through a left anterolateral thoracotomy which can be extended across the sternum

      2. Hemodynamically Stable Patient
        • must be thoroughly evaluated to exclude mediastinal injury
        • CT angiography is performed to rule out great vessel injury
        • esophagography and esophagoscopy are next performed to rule out esophageal injury
        • bronchoscopy should be performed to rule injury to the tracheobronchial tree
        • echocardiography is used to evaluate the heart and pericardium
        • may be a role for thoracoscopy in some patients
        • 30% of patients will have a positive diagnostic evaluation requiring operative intervention

Diaphragmatic Injuries

  1. Diaphragmatic Rupture
    1. Mechanism of Injury
      • blunt trauma produces large radial tears that lead to acute herniation; penetrating trauma produces small defects that can take years to develop into diaphragmatic hernias
      • complications of acute herniation include respiratory compromise and strangulation of peritoneal contents
      • left side is involved much more often than the right side – likely because the liver protects the right side of the diaphragm

    2. Diagnosis
      • commonly overlooked
      • chest x-ray is often misinterpreted as showing an elevated hemidiaphragm, acute gastric dilatation, or loculated pneumothorax
      • the presence of bowel or stomach (N-G tube) in the thoracic cavity on chest x-ray or CT confirms the diagnosis
      • thoracoscopy or laparoscopy (can miss posterior perforations) have also been used in unclear cases

      Diaphragmatic Rupture
    3. Management
      • should be repaired via an abdominal approach due to the high incidence of associated abdominal injuries
      • most cases can be managed with debridement of nonviable tissue and primary repair of the defect with nonabsorbable suture
      • a prosthetic patch is reasonable in a noncontaminated field







References

  1. Cameron, 11th ed., pgs 1005 - 1009, 1085 - 1087
  2. Sabiston, 20th ed., pgs 424 – 432
  3. ATLS, 10th ed., pgs 62 - 81