Thoracic Trauma

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Chapter 62 Thoracic Trauma

Howard Kadish, MD

1 What are the most common injuries in blunt and penetrating thoracic trauma?

Blunt thoracic trauma: Lung contusions (58%), pneumothorax or hemothorax (38%), and rib fractures (38%)

Penetrating thoracic trauma: Pneumothorax or hemothorax (64%), diaphragmatic lacerations (15%), cardiac injuries (13%), and vascular injuries (10%)

2 How does thoracic trauma differ in children and adults?

Pediatric thoracic trauma differs from adult thoracic trauma in mechanism of injury, type of injury, and other organ systems involved. Falls are the most common mechanism of injury in infants and children. Older children are often injured as pedestrians or unrestrained passengers in motor vehicle accidents. Adolescents are more likely to be occupants in motor vehicle–related accidents and to experience penetrating injuries secondary to violence.

Lung contusion is the most common pediatric thoracic injury, with intrapleural injury second. Only 30% of children, compared with 50–75% of adults, sustain rib fractures because of increased compliance in the pediatric thoracic cage secondary to increased cartilage content and greater elasticity of the bones. Thus, a child may have an internal injury (lung contusion) without external evidence of trauma (rib fracture, laceration, bruising). The pediatric trachea has a smaller internal diameter than the adult trachea; therefore, a small amount of obstruction secondary to blood, secretions, or edema can cause significant respiratory distress and hypoxia. The younger pediatric patient is also more sensitive to hypoxia and may develop reflex bradycardia or asystole. In evaluating pediatric patients with thoracic trauma, the health care provider must consider head, neck, and intra-abdominal injuries because approximately 80% of cases of thoracic trauma in children are part of multisystem injury. Thoracic trauma is routinely associated with abdominal trauma in children because the chest and abdominal cavities lie in close proximity.

3 How do I evaluate a patient with thoracic trauma?

The ABCs (airway, breathing, circulation) of trauma management apply regardless of the organ system injured. The injured child should be evaluated according to the primary survey of trauma management. Indications for endotracheal intubation in thoracic trauma patients include depressed neurologic status, inadequate oxygenation or ventilation, compromised circulatory status, or unstable airway (including burns). If a patient has an abnormal examination but appears to be oxygenating and ventilating well and is not in shock, chest radiography is indicated. If breathing is inadequate after endotracheal intubation, with asymmetry of breath sounds, intervention is required prior to chest radiography. Pericardial tamponade, tension pneumothorax, or hemothorax should be considered in poorly perfused patients with signs of shock in whom other sources of blood loss have been excluded and volume resuscitation has not improved clinical status. Once the patient is stabilized and immediate life-threatening injuries, such as airway obstruction, tension pneumothorax, hemothorax, and pericardial tamponade, are treated, chest radiography and thoracic computed tomography provide valuable information about other potentially life-threatening and operative injuries.

4 What are the predictors of thoracic injury in children sustaining blunt trauma?

Low systolic blood pressure

Elevated respiratory rate

Abnormal results of thoracic examination

Abnormal chest auscultation findings

Glasgow Coma Scale score < 15

5 Which thoracic injuries require operative intervention?

Tracheal/bronchial rupture

Laceration of lung parenchyma, internal mammary artery, or intercostal artery

Esophageal disruption

Diaphragmatic hernia

Pericardial tamponade

Great vessel laceration

6 Describe signs and symptoms related to each operative thoracic injury

See Table 62-1.

Table 62-1 Signs and Symptoms of Thoracic Injuries

Injury	Signs and Symptoms
Tracheal/bronchial rupture	Active chest tube air leak
Lung parenchyma	Chest tube bleeding > 2–3 mL/kg/hr
Internal mammary or intercostal artery laceration	Hypotension unresponsive to transfusions
Esophageal disruption	Abnormal esophagogram (leak) or esophagoscopic result Gastric contents in the chest tube
Diaphragmatic hernia	Abnormal gas pattern in hemithorax Displaced nasogastric tube in hemithorax
Pericardial tamponade	Positive pericardiocentesis
Great vessel laceration	Widened mediastinum Tracheal or nasogastric tube deviation Blurred aortic knob Abnormal aortogram (gold standard)

7 What signs and symptoms are associated with pulmonary contusion?

Patients with moderate to severe pulmonary contusions may be tachypneic, with abnormal breath sounds and an oxygen requirement secondary to shunting within the lung. In one study of patients with mild pulmonary contusions, a finding of tachypnea, tenderness, or abnormal breath sounds was 100% sensitive for all positive radiographs in trauma.

Gittelman M, Gonzalez-del-Rey J, Brody A, et al: Clinical predictors for the selective use of chest radiographs in pediatric blunt trauma evaluations. J Trauma 55:670–676, 2003.

Ruddy R: Trauma and the paediatric lung. Paediatr Respir Rev 6:61–67, 2005.

8 What signs and symptoms are associated with pneumothorax?

Patients may be asymptomatic, report pleuritic chest pain, have tachypnea, or be in severe respiratory distress. Physical examination may be normal or reveal diminished or absent breath sounds, crepitus, or hyperresonance to percussion on the side of the pneumothorax.

9 How do I diagnose and treat patients with pneumothorax?

In asymptomatic or mildly symptomatic patients, a chest radiograph is helpful in diagnosing and determining type of treatment. If the pneumothorax is small and the patient asymptomatic, hospital observation and administration of 100% oxygen are all that is necessary. A small pneumothorax is classically described as < 15%, although it is common to underestimate the size of a pneumothorax on plain films and to find a much more extensive lesion on a CT scan. If the patient is in respiratory or cardiovascular distress, the diagnosis is made clinically. Tube thoracostomy should be performed. It is also indicated in patients undergoing positive-pressure ventilation or requiring air transport. An asymptomatic patient may rapidly become symptomatic if a small, simple pneumothorax progresses to a tension pneumothorax.

10 Should thoracic helical CT replace chest radiography in the initial management of blunt trauma in the pediatric patient?

No, even though helical CT has been shown to be more sensitive than chest radiography in diagnosing thoracic injuries, thoracic trauma makes up less than 20% of all pediatric traumas. Performing thoracic CT on all pediatric trauma patients would increase costs and patient radiation dose, with little clinical improvement. Thoracic CT should be used only in patients with suspected thoracic injury (see question 4).

Renton J, Kincaid S, Ehrlich P: Should helical CT scanning of the thoracic cavity replace the conventional chest x-ray as a primary assessment tool in pediatric trauma? An efficacy and cost analysis. J Pediatr Surg 38:793–797, 2003.

11 What is the most common complication of an intrapleural injury?

Tension pneumothorax is the most common complication of an intrapleural injury, developing in up to 20% of children after simple pneumothorax. Tension pneumothorax occurs with progressive accumulation of air within the pleural cavity, which not only collapses the ipsilateral lung but also compresses the contralateral lung. Patients may present in severe respiratory distress, with decreased breath sounds on the side of the pneumothorax and a shift of mediastinal structures to the contralateral side. Because the inferior vena cava is relatively fixed in place and cannot shift as much as the superior vena cava, venous return to the heart is reduced. The patient may appear tachycardic, peripherally vasoconstricted, and in hypotensive shock. Whenever a trauma patient suddenly deteriorates, the treating physician must return to assessing the airway and breathing before focusing on circulation.

12 How do I treat a patient with a tension pneumothorax?

Initial treatment consists of needle decompression performed in the midclavicular line, at the level of the second intercostal space of the ipsilateral side. With a tension pneumothorax, an immediate release of air should be noted. If this sign is positive, needle decompression is only a temporizing measure and must be followed by tube thoracotomy. Tube thoracotomy usually is done in the midaxillary line at the level of the fifth intercostal space (nipple level). Chest radiography is performed only after insertion of the chest tube and should not be used to diagnose tension pneumothorax in symptomatic patients. If significant air leak continues after chest tube placement, a tracheobronchial rupture must be considered.

13 How can I tell if a patient has a tracheobronchial injury?

Injury to the tracheobronchial tree in children is rare (incidence < 1%). It is caused most commonly by acceleration or deceleration forces. Mechanism of injury (fall, crush, and direct blow) provides an important clue. Clinical signs include cyanosis, hemoptysis, tachypnea, and subcutaneous emphysema (cervical, mediastinal, or both). A continued air leak after insertion of a thoracostomy tube should alert the physician to the possibility of a bronchial tear. In the absence of pneumothorax, suspect tracheal rupture if pneumomediastinum or cervical emphysema is present. Immediate surgical consultation is indicated.

14 How is tracheobronchial injury treated?

Treatment includes initial airway stabilization followed by bronchoscopic evaluation of the airway. According to numerous reports in the literature, a partial tracheal tear may become complete after endotracheal intubation. Therefore, if the airway is stable, perform oral tracheal intubation in the operating room under bronchoscopic guidance. If the airway is unstable and emergent endotracheal intubation is needed, prepare for backup measures, such as cricothyroidotomy, tracheostomy, or fiberoptic bronchoscopy.

15 How can I tell if a patient has an esophageal injury?

Esophageal injury is rare in children but presents a diagnostic challenge when it does occur. The most common cause for esophageal perforation in children is iatrogenic, followed by penetrating trauma (gunshot or stab wound). Patients with an esophageal rupture in the cervical region may report neck stiffness or neck pain. They may regurgitate bloody material and have cervical subcutaneous emphysema or odynophagia. A lateral neck radiograph may show retroesophageal emphysema. In the thoracic region, patients may present with abdominal spasms and guarding, chest pain, subcutaneous emphysema, tachycardia, or dyspnea. A chest radiograph may show pneumothorax, pneumomediastinum, or an air–fluid level in the mediastinum.

16 How are esophageal injuries treated?

Patients with suspected esophageal perforation should receive adequate volume resuscitation, placement of a nasogastric tube, and antibiotics covering gram-positive, gram-negative, and anaerobic organisms. Esophagography, esophagoscopy, or both can make the diagnosis of esophageal perforation. Once the diagnosis is made, prompt surgical correction is mandatory. If the diagnosis is made within 24 hours, the mortality rate is approximately 5%. Diagnosis delayed for more than 24 hours after injury is associated with a mortality rate of 70%.

17 On which side is a diaphragmatic injury seen more commonly?

Approximately 80% of diaphragmatic injuries occur on the left. The left diaphragm is relatively unprotected, whereas the liver protects the right side. Right-sided diaphragmatic injuries are associated with increased mortality; patients usually have a greater physiologic insult and more associated injuries.

18 How is the diagnosis of a traumatic rupture of the aorta (TRA) made?

The gold standard for diagnosing TRA is aortography. Thoracic CT is only 55–65% accurate but helps to diagnose associated injuries. In one study, transesophageal echocardiography was shown to be highly sensitive and specific for detecting injury to the thoracic aorta. If the patient is stable and TRA is a concern, aortography should be performed. Life-threatening intracranial, thoracic, or intra-abdominal injuries must be evaluated and stabilized before aortography is done. If the patient is unstable, transesophageal echocardiography can be performed in the operating room while other life-threatening injuries are treated. Early diagnosis is imperative in patients with TRA. Morbidity and mortality increase threefold if operative intervention is delayed more than 12 hours.

19 How do patients with pericardial tamponade present?

Pericardial tamponade initially may be difficult to diagnose because associated injuries obscure the clinical signs and symptoms. Patients may present with distant heart sounds, low blood pressure, poor perfusion, narrow pulse pressure, or electromechanical dissociation. Pulsus paradoxus, with blood pressure falling more than 10 mmHg during inspiration, occurs in less than half of patients with pericardial tamponade and should not be relied on to make the diagnosis. Chest radiography may show an enlarged heart, and an electrocardiogram may show low-voltage QRS waves. Neither of these tests is diagnostic for pericardial tamponade, and treatment (pericardiocentesis) should not be delayed in unstable patients. In stable patients, an echocardiogram can demonstrate fluid within the pericardial sac.@

20 How concerned should I be about blunt cardiac injury in patients with thoracic trauma?

Blunt cardiac injury should be considered in any patient with thoracic trauma (e.g., a child hit by a fast-pitched baseball) who develops cardiac arrhythmia, a new murmur, or congestive heart failure. Patients with suspected blunt cardiac injury can be monitored in the emergency department or hospital; if no arrhythmias develop on electrocardiography, they can safely be sent home. Creatine phosphokinase–MB ratios have a high false-positive rate and are not a helpful screening tool. Transesophageal echocardiography should be performed in patients with thoracic trauma who have an abnormal electrocardiogram, arrhythmia, or new heart murmur. It is more sensitive in detecting myocardial injury than transthoracic echocardiography. A child with suspected blunt cardiac injury who is hemodynamically stable and has no arrhythmias is unlikely to develop a serious life-threatening arrhythmia or pump failure. Any patient with suspected blunt cardiac injury who is hemodynamically unstable or has arrhythmias should undergo transesophageal echocardiography and be admitted to the intensive care unit.

KEY POINTS: THORACIC TRAUMA

1 The most common injuries in blunt thoracic trauma are lung contusions (58%), pneumothorax or hemothorax (38%), and rib fractures (38%).

2 Thoracic CT should be part of the initial evaluation of pediatric trauma patients if a lung contusion, pneumothorax, or a hemothorax is suspected or if the cause of the patient’s respiratory distress is unknown.

3 Myocardial contusion is the most common and ventricular rupture the most lethal of blunt cardiac injuries.

4 Patients with a traumatic rupture of the aorta may present with hypotension, paraplegia, anuria, or absent/diminished femoral pulses.

5 Radiographic findings of a traumatic rupture of the aorta may include a widened mediastinum, blurred aortic knob, pleural cap, or tracheal or nasogastric tube deviation.

6 Suspect commotio cordis and ventricular fibrillation in any patient who has become unconscious immediately after blow to the chest.

21 What are the four conditions that must be present for sudden circulatory arrest to occur after a nonpenetrating blow to the chest (commotio cordis)?

1 The blow must strike the chest in the area of the heart with force.

2 The object must have sufficient mass (baseball, hockey puck, knee).

3 The blow must strike the chest during the ventricular vulnerable period (T wave).

4 The ventricles must have a large enough mass (> 3.5 kg).

Geddes L, Roeder R: Evolution of our knowledge of sudden death due to commotio cordis. Am J Emerg Med 23:67–75, 2005.

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