THORACIC TRAUMA
MATTHEW EISENBERG, MD AND DAVID P. MOONEY, MD, MPH
GOALS OF EMERGENCY THERAPY
The initial goals of emergency therapy for the child with thoracic trauma, just as for all forms of major trauma, are assessment and stabilization of airway, breathing, and circulation, all of which are at increased risk due to the location of vital structures within the thorax. A thorough primary trauma survey, with immediate steps to correct any deficits in airway, breathing, and circulation before moving on to the next element of assessment, is critical. The provider should be prepared to emergently intubate the trachea, provide mechanical ventilation, administer both intravenous fluids (IVF) and red blood cells, and perform other emergency interventions such as thoracentesis, thoracostomy, and pericardiocentesis as indicated.
Respiratory compromise in children with thoracic trauma may be due to obstruction of the airway, injury to the chest wall, lung parenchyma, or central nervous system, or shock. Thoracic hemorrhage, obstruction of venous return, or direct injury to the heart may lead to circulatory compromise and shock.
The evaluation of the child with thoracic trauma is complicated by both physical and developmental differences from adults. Detailed further in the sections that follow, these include increased compliance of the thoracic cage, greater susceptibility to air and fluid in the pleural space, a shorter, more narrow trachea at greater risk of obstruction, and greater sensitivity to hypoxia. Due to fear, pain, separation from caregiver and/or young age, an injured child may not be able to articulate their complaints or comply with the examination. Therefore, attention to nonverbal cues, vital signs, and careful observation of respiratory and circulatory status are crucial. Because approximately 80% of thoracic trauma occurs as part of a multisystem injury, the physician must also consider head, neck, and intra-abdominal injuries when evaluating a child with chest trauma. An overview of the approach to the child with blunt thoracic trauma is shown in Figure 123.1.
KEY POINTS
Significant thoracic trauma in the pediatric population is relatively uncommon, accounting for only 4% to 6% of children admitted to pediatric trauma centers.
Despite a high rate of scene fatalities, mortality rates for children who reach the hospital with isolated thoracic trauma are low; this rate triples when thoracic trauma occurs concurrently with head or abdominal trauma.
Blunt trauma occurs far more frequently than penetrating trauma and lung injuries outnumber those to the heart and great vessels.
Emergency evaluation requires careful observation and examination for evidence of impaired respiration or circulation, including any abnormal vital signs.
Be prepared to immediately secure the airway and support breathing and circulation.
Most thoracic injuries do not require intervention and those that do most commonly require only tube thoracostomy.
RELATED CHAPTERS
Signs and Symptoms
• Respiratory Distress: Chapter 66
Clinical Pathways
Medical, Surgical, and Trauma Emergencies
• Approach to the Injured Child: Chapter 2
• Child Abuse/Assault: Chapter 95
• Abdominal Trauma: Chapter 111
• Musculoskeletal Trauma: Chapter 119
FIGURE 123.1 Algorithm showing approach to blunt thoracic trauma. Official reprint from UpToDate® “http://www.uptodate.com” © 2015 UpToDate®.
PNEUMOTHORAX AND HEMOTHORAX
CLINICAL PEARLS AND PITFALLS
• Pneumothorax is one of the most common injuries seen in thoracic trauma.
• The unstable patient with suspected tension pneumothorax requires emergent needle decompression, even before radiologic evaluation, followed by tube thoracostomy.
• The stable pediatric patient with suspected thoracic trauma may be assessed by chest radiography and bedside ultrasound (US) and without computed tomography (CT) imaging.
• Tube thoracostomy is recommended for patients with pneumothoraces that are large, associated with respiratory compromise, or when air transport is required.
• Positive pressure ventilation by itself is not an indication for tube thoracostomy in patients with a small pneumothorax detected on CT only.
• Hemothorax can lead to both respiratory and circulatory compromise, as a large volume of blood can be lost into the pleural space.
• Treatment of hemothorax includes tube thoracostomy and support of circulation with both crystalloid products and blood transfusion as needed.
Current Evidence
Pneumothorax is the second most commonly encountered injury in blunt thoracic trauma and the most common in penetrating thoracic trauma. Air within the pleural cavity can arise from penetration of the chest wall, disruption of the lung parenchyma, a tear of the tracheobronchial structures, or esophageal rupture. Hemothorax is much more common in penetrating than blunt thoracic trauma. In blunt thoracic trauma, a hemothorax can occur from rib fractures lacerating the lung, pulmonary parenchymal injuries unrelated to rib fractures, lacerations of the chest wall vessels, or disruption of the vascular structures in the mediastinum or hilum. The most common cause of a hemothorax is injury to the intercostal or internal mammary arteries, whereas injury to the lung or great vessels is less common but more significant. Intraperitoneal hemorrhage may lead to a hemothorax if associated with disruption of the diaphragm.
Air and fluid within the pleural space more easily shift the mediastinum in children, compromising venous return and cardiac output to a greater extent than in adults. Available data suggest that the mortality rate for pneumothorax (15%) is substantially lower than with hemothorax (57%). Hemothorax secondary to an injury of the great vessels usually results in death at the scene.
Goals of Treatment
Immediate recognition and stabilization of airway, breathing, and circulation is crucial to management of pneumothoraces and hemothoraces. Opening and then securing the airway with endotracheal intubation is the first step for a child with severe respiratory distress, inadequate oxygenation or ventilation, or depressed mental status after trauma. Breathing may be supported via mechanical ventilation and evacuation of intrapleural air and blood. Circulation may become impaired during tension physiology via obstruction of venous return, and evacuation of the pleura via needle or tube thoracostomy is immediately necessary. Circulation may also be affected by blood loss into the thorax necessitating volume replacement with appropriate IVF and possible blood transfusion.
For the stable patient with pneumo- or hemothorax, the focus is on careful evaluation and treatment to prevent deterioration. Chest radiograph (CXR) and US may be helpful to identify the extent of the injury and the need for intervention. Depending on the clinical progression, treatment may involve observation, tube thoracotomy, or surgical intervention.
Clinical Considerations
Clinical Recognition
Pneumothorax or hemothorax should be suspected in any child with a history of thoracic trauma who presents with chest pain, shortness of breath, respiratory distress, hypoxia, or evidence of shock. Physical examination alone may be sufficient to make the diagnosis in patients with a large hemothorax or pneumothorax or severe complications such as tension physiology, but smaller lesions may be missed by examination alone. All patients with a mechanism concerning for a thoracic injury should undergo prompt radiologic evaluation with CXR, as an initial normal physical examination may be misleading. Where available, bedside US can be used to augment the initial physical examination as it may facilitate identification of even small amounts of air or blood in the pleural space.
Triage Considerations
Children with traumatic pneumothorax or hemothorax require immediate evaluation utilizing Advanced Trauma Life Support (ATLS) protocols and activation of the appropriate local trauma response. In planning for a trauma response, preparations should be made for both needle aspiration of pleural air and placement of a chest tube, so that these procedures can be performed without delay if indicated by the patient’s clinical condition or diagnostic workup.
Clinical Assessment
The child with suspected pneumothorax or hemothorax should undergo a thorough primary survey, looking for signs of compromised airway, breathing, or circulation. Careful attention to vital signs, particularly tachycardia, tachypnea, and hypoxemia, may lead to discovery of impaired physiology not otherwise detected by physical examination. It is important to recognize that due to children’s excellent vascular compensation abilities, hypotension is a late finding in pediatric shock and a normal blood pressure therefore does not rule out circulatory compromise.
Some patients with a pneumothorax may be asymptomatic. Others may be tachypneic, complain of pleuritic chest pain, or be in severe respiratory distress. Physical examination may be normal or may reveal diminished or absent breath sounds, crepitus, or hyperresonance to percussion on the side of the pneumothorax. If a tension pneumothorax develops, findings may include tracheal deviation to the contralateral side and distended neck veins from impaired venous return to the heart through the deviated superior vena cava. These physical findings may be difficult to discern in a fully immobilized child in a noisy resuscitation room.
Patients with hemothorax may present in respiratory distress or profound shock secondary to obstruction of venous return or blood loss. Decreased breath sounds are noted on the affected side, and there may be tracheal or mediastinal deviation. Thirty to 40% of the patient’s blood volume may be rapidly lost in the pleural cavity with major vessel lacerations. Bleeding from the intercostal or internal mammary arteries usually stops as systemic blood pressure falls and reexpansion of the lung may provide some tamponade effect.
Tension Pneumothorax
A tension pneumothorax is the most common complicated intrapleural injury. Tension pneumothorax develops in up to 20% of children after simple pneumothorax. A tension pneumothorax occurs when there is progressive accumulation of air within the pleural cavity. A laceration to the chest wall, pulmonary parenchyma, or tracheobronchial tree may function as a one-way valve, allowing air to enter but not leave the pleural space. The progressive accumulation of air within the pleural cavity not only collapses the ipsilateral lung, but it also compresses the contralateral lung (see Fig. 123.2). These patients may present in severe respiratory distress with decreased breath sounds on the side of the pneumothorax. There is also a shift of the mediastinal structures to the contralateral side. Two-thirds of the blood supply to the body is returned to the heart via the inferior vena cava. Because the inferior vena cava is relatively fixed in place as it passes through the diaphragm and cannot shift as much as the superior vena cava, venous return to the heart is reduced.
FIGURE 123.2 Tension pneumothorax with a mediastinal shift.
Patients with a tension pneumothorax or hemothorax demonstrate tension physiology: tachycardia and peripheral vasoconstriction and, if left untreated, will progress to shock. Initial treatment for tension physiology consists of needle decompression. An immediate release of air should be noted and the patient’s hemodynamic status should improve. The needle decompression is only a temporizing measure and must be followed by tube thoracostomy.
Open Pneumothorax
An open pneumothorax is the result of penetrating trauma. There is a direct connection between the pleural space and the atmosphere, impeding ventilation. Initial treatment includes placement of an occlusive dressing at the wound site. This is best done when the patient is in full expiration. As in a bronchial tear or lung parenchymal injury, air may enter but not leave the pleural space, creating a ball-valve effect. A chest tube should be placed immediately to prevent development of a tension pneumothorax. The chest tube should be inserted at a site different than the open wound. Larger open chest wounds may need surgical closure.
Diagnostic Testing
Chest Radiograph
A CXR remains the most widely used test for the diagnosis of hemothorax and pneumothorax. Both conditions are better visualized in the upright position than supine. Plain radiographic signs of a pneumothorax may include identification of the pleural line, a hyperlucent hemithorax, pleural air at the lung base, and/or an unusually well-defined heart and mediastinal outline due to pleural air rising anteriorly. A tension pneumothorax is indicated by the presence of midline shift to the contralateral side of the pneumothorax (see Fig. 123.3). Smaller pneumothoraces may be better visualized by positioning the patient in the lateral decubitus position with the concerning side up. Expiratory CXRs do not add significantly to the evaluation. Hemothorax on CXR may appear as blunting of the costophrenic angle, haziness or opacification of the hemithorax, or a visible air–fluid level.
Bedside Ultrasound
Bedside US has become part of the standard assessment of trauma patients due to its ability to rapidly detect injuries and inform management strategies. The major finding of pneumothorax is absence of lung sliding, while hemothorax is determined by the presence of fluid in the pleural space. Studies in adults have shown the extended focused assessment with sonography for trauma (E-FAST) examination to be more sensitive in the detection of pneumothorax than supine radiographs with a sensitivity between 50% and 80% and specificity of 95% to 100% when compared to chest CT. In the multiply injured or unstable patient, US may be particularly valuable in prioritizing further evaluation and interventions, particularly in adult patients.
FIGURE 123.3 A 5-year-old girl fell off and was then kicked in the chest by a horse. Upon arrival of the life-flight team, the patient was found to be in both respiratory and cardiovascular distress. Chest radiograph demonstrated a left-sided tension pneumothorax. The patient was intubated, and a chest tube was placed before the patient was transported. After the intubation and chest tube insertion, both the patient’s respiratory and cardiovascular status improved.
Reported sensitivity of the FAST examination in children is lower than that noted in adults. In addition, children are less likely to undergo operative repair even when free fluid in the abdomen is identified, therefore the role for FAST testing is different in children than adults. Nonetheless, with thoracic trauma, identification of air or blood in the pleural space on bedside US may rapidly influence the decision for tube thoracostomy in children with respiratory or hemodynamic compromise.
Management
Needle Decompression
Initial treatment for pneumothorax may consist of observation alone, placement of a chest tube, or needle thoracentesis. Tension pneumothorax, however, should always be treated with immediate needle decompression. This is performed by insertion of a large-bore intravenous (IV) catheter in the midclavicular second intercostal space of the ipsilateral side. If there is a tension pneumothorax, an immediate release of air should be noted. Evacuation can be facilitated by attaching the catheter to a two-way stopcock and 60-cc syringe, allowing air to be continuously pulled from the pleural space although the placement of the catheter alone should temporarily resolve the tension physiology until tube thoracostomy can be performed.
Chest Tube
Tube thoracostomy is indicated in the symptomatic patient with pneumothorax or those requiring air transport. Management of asymptomatic pneumothoraces identified on CT but not visible on plain radiograph is controversial, but tube thoracostomy does not appear to be required, even in patients undergoing positive pressure ventilation.
Tube thoracostomy should be done in the midaxillary line at the level of the fifth intercostal space (nipple level). If the pneumothorax is not relieved and a significant air leak continues after chest tube placement, a tracheobronchial rupture must be considered. Evidence suggests that for a simple pneumothorax, placement of a pigtail catheter instead of a chest tube has similar efficacy while causing less pain to the patient. While data in children are lacking, pigtail catheter placement is often preferred to chest tube for management of pneumothoraces due to less need for procedural sedation and postprocedural pain medication.
Tube thoracostomy, and not pigtail catheter placement, is the treatment of choice in patients with a hemothorax in order to evacuate blood from the pleural cavity, reexpand the lung, and prevent or treat any mediastinal shift. Many hemothoraces may actually represent hemopneumothoraces. As with a pneumothorax, the chest tube is placed in the midaxillary line at the level of the fifth intercostal space (nipple level). Patients should be typed and crossed for packed red blood cells and adequately volume resuscitated, preferably with two large IV lines in place. For larger hemothoraces, donor blood should be at the patient’s bedside prior to tube thoracostomy if time permits. After placement of a chest tube, blood should be slowly evacuated from the pleural space. Blood within the pleural cavity may tamponade a significant bleeding source within the chest and evacuating that blood may cause new bleeding to occur. Patients can exsanguinate rapidly, which is why IV access, adequate volume resuscitation, and blood available for transfusion should be a priority. Thoracostomy drainage needs to be closely monitored. Large ongoing blood loss from a chest tube should be collected in a system that allows autotransfusion.
Thoracotomy
Thoracotomy is indicated for bleeding that continues at a rate of greater than 1 to 2 mL/kg/hr, inability to expand the lung, or retained blood within the pleural cavity. Failure to adequately drain a hemothorax may lead to restrictive lung disease from a fibrothorax or an empyema from the clotted material becoming infected.
Disposition
All patients with a traumatic pneumothorax or hemothorax require admission to the hospital. If the pneumothorax is small and the patient is asymptomatic, hospital observation and passive administration of oxygen via a nonrebreather mask is all that is necessary. A small pneumothorax is classically described as being less than 15% of the hemithorax, although it is common to underestimate the size of a pneumothorax using plain films. An asymptomatic patient may rapidly become symptomatic if a small, simple pneumothorax progresses to a large or tension pneumothorax; therefore, even asymptomatic patients with a pneumothorax should be admitted to the hospital for observation. Patients with chest tubes should be hospitalized on a unit that is capable of monitoring and troubleshooting the tube and the collection device.
An unstable airway, respiratory distress, severe hypoxia, ongoing blood loss, and presence of other severe injuries are among the indications for admission to an intensive care unit.
PULMONARY CONTUSIONS
CLINICAL PEARLS AND PITFALLS
• Pulmonary contusion is the most common intrathoracic injury in children.
• While many contusions cause only mild symptoms such as chest pain, more severe injuries can lead to hypoxemia and respiratory failure.
• Pulmonary contusions may not show up on CXR for 4 to 6 hours after the injury, and in some cases may never be identified on plain films.
• Given the force necessary to cause a pulmonary contusion, a high index of suspicion for other associated injuries is required.
Current Evidence
Pulmonary contusion is the most common thoracic injury in children. Pulmonary contusion occurs when a blunt force is applied to the lung parenchyma, though the injury can also be seen in penetrating trauma. The pediatric thoracic cage provides less protection from blunt force impact compared to adults, secondary to greater cartilage content and the greater elasticity of the bones. Therefore, external kinetic energy applied to the thorax is transferred more readily through the chest wall to the underlying organs. Thus, a pediatric patient is more likely than an adult to have an internal injury such as a lung contusion without external evidence of trauma (rib fracture, laceration, bruising).
As in any contusion or bruise, the capillary network becomes damaged, leaking fluid into the surrounding tissues. A ventilation:perfusion mismatch will occur because of the extravasation of fluid into injured lung parenchyma, interfering with oxygenation. As the edema and swelling worsen, the patient’s respiratory status will deteriorate if the contusion is large.
Clinical Considerations
Clinical Recognition
Pulmonary contusion should be suspected in any child with blunt thoracic trauma who presents with chest pain, difficulty breathing, or unexplained hypoxia. The contusion may be visualized on radiography or inferred from the absence of another explanation for these symptoms (such as pneumothorax). Due to the pliable nature of the pediatric chest wall, pulmonary contusions can often be seen in the absence of rib fracture. When present, however, rib fractures as well as chest wall ecchymosis should further raise suspicion for underlying parenchymal injury.
Triage
While a stable pulmonary contusion may not require any specific therapy, patients are at high risk of deteriorating respiratory status and therefore require an expedited evaluation. In addition, the presence of such an injury indicates that sufficient force was applied to the thorax to warrant thorough evaluation for additional injuries.
Clinical Assessment
Initial assessment should focus on assessing and stabilizing the airway, breathing, and circulation, as well as the identification of other associated injuries. Vital sign abnormalities seen with moderate-to-severe pulmonary contusions may include tachypnea and hypoxemia due to shunting within the lung. Patients may complain of chest pain or shortness of breath, and physical examination may reveal chest wall bruising and tenderness, with focally diminished breath sounds in the affected lung. These latter findings are nonspecific, however, and their absence should not be used to rule out pulmonary contusion without imaging.
FIGURE 123.4 Right lower lobe pulmonary contusion in a patient with associated rib fractures. Subcutaneous air is also noted in the adjacent soft tissue.
Management
When pulmonary contusion is suspected, CXR is the imaging modality of choice (see Fig. 123.4). However, the contusion itself may not be visible on CXR for 4 to 6 hours after the injury, and even then false-negative rates of up to 33% have been reported.
Although more sensitive than CXR in detecting pulmonary contusion, a chest CT scan is usually unnecessary unless a significant injury to the vasculature is suspected, as management will depend on clinical condition of the patient and not the radiographic size of the contusion.
Treatment of pulmonary contusion is supportive. If required, supplemental oxygen should be administered. If the patient cannot maintain oxygenation despite passive supplemental oxygen delivery, endotracheal intubation and mechanical ventilation with positive pressure is the treatment of choice. Fluid restriction is helpful to avoid exacerbation of pulmonary edema, though must be balanced against the fluid needs arising from concurrent injuries to other organ systems and shock in the severely injured child. Patients may require high inflation pressures to maintain adequate oxygenation, which combined with injury to the lung leads to high risk of barotrauma and pneumothorax.
Disposition
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