Traumatic injury is the most common cause of morbidity and mortality in children age 1 to 14 years.^1,2 Thoracic trauma is relatively rare in children but still accounts for approximately 5% to 10% of pediatric injuries and is a significant cause of deaths secondary to trauma.^3–5 The highest mortality rates involve injury to the heart and great vessels, hemothorax, and lung laceration.

Blunt trauma is the most common cause of thoracic injury; however, penetrating trauma continues to rise in the adolescent population. Infants and toddlers are most often victims of passive injury such as motor vehicle crashes, falls, and nonaccidental trauma. School-age children and adolescents have an additional risk of sports-related chest injuries. Adolescents are particularly at risk for high-energy injuries related to motor vehicle crashes, extreme sports, violence, and suicide. The most common injuries sustained include pulmonary contusion, pneumothorax, hemothorax, pneumohemothorax, and rib fractures.

When trauma results in cardiopulmonary arrest in the field, survival for both pediatric and adult victims is poor. Overall trauma mortality rate has been estimated at 95%.⁶ However, the National Pediatric Trauma Registry estimates pediatric traumatic arrest to be far better than their adult counterparts, with up to 25% of children surviving to hospital discharge.⁷

The impact of designated trauma centers on pediatric outcomes continues to be researched. Several studies show improved survival and overall improved functional outcomes for injured children when initial evaluation and resuscitation occur at designated pediatric trauma centers.^8–14 Other studies show no difference in survival for children cared for at adult trauma centers.^15,16 Despite the differences in findings, most pediatric trauma patients must be initially evaluated and stabilized in nonspecialty centers until arrangements for transport to an appropriate facility are made for definitive care. Because of anatomic reasons, even seemingly benign mechanisms of trauma have the potential to produce severe injuries in infants and young children.

BLUNT THORACIC TRAUMA

The National Pediatric Trauma Registry and trauma research show that approximately 80% to 90% of pediatric chest injuries are due to blunt forces, compared with 10% to 20% from penetrating trauma.^7,10,17,18 Most blunt injuries are caused by motor vehicle crashes, falls, and bicycle and pedestrian accidents. The mechanism of injury is important because of recognizable patterns of injury associated with particular mechanisms. Half of all serious blunt chest trauma results in rib fractures and pulmonary contusions, with an additional 20% complicated by pneumothoraces and 10% by hemothoraces.^4,18

PENETRATING THORACIC TRAUMA

Although penetrating mechanisms account for only about 15% of thoracic trauma in childhood, the incidence is increasing, especially with respect to gunshot wounds. In one study, penetrating chest trauma was more common in adolescents (58%), and the rate of chest thoracotomy was also higher in this age group.¹⁰ The overall mortality is about the same for blunt and penetrating trauma. Injury severity score greater than 25 and a corrected admission pH of less than 7.3 have been associated with higher mortality and an increased need for surgical intervention.¹⁹ Patients who succumb to penetrating chest trauma often experience massive hemorrhagic shock from exsanguination and loss of cardiac filling potential associated with major vascular injuries, massive hemothorax, cardiac tamponade, and/or tension pneumothorax. In some cases, the use of autotransfusion is beneficial to patients with massive hemorrhagic shock.¹⁹ Penetrating injuries from ball bearing (BB) or pellet weapons are often regarded as trivial, but children injured at close proximity may be at risk for life-threatening injuries that may be missed despite extensive workups including CT scans and angiography. A case report of two children with low-velocity penetrating thoracic injuries by pump-action air rifles highlight the need for heightened awareness for serious potential injury from this mechanism.²⁰ Both patients had mediastinal vascular injuries despite normal or minimally abnormal findings on CT and angiography. One child had an undiagnosed intrapericardial ascending aorta injury and died suddenly 5 days after this injury. The other child underwent direct surgical exploration to discover a pseudoaneurysm within the pericardial sac and made a full recovery.

It is important to maintain a high index of suspicion for concomitant abdominal injury with penetrating trauma at or below the level of the sixth rib anteriorly, below the scapula posteriorly, or when stomach contents, chyme, or saliva are recovered from the chest tube. Gunshot wounds to the chest are associated with abdominal injuries in 30% to 40% of patients.¹⁹ Therefore, “isolated” thoracic trauma does not exclude abdominal injury, especially in the presence of abdominal tenderness or developing peritonitis.

There are critical differences in the pediatric anatomy that affect a child’s risk of sustaining significant injuries from thoracic trauma (Table 26-1). The increased compliance of cartilaginous ribs allows for the dissipation of impact forces and protection of the ribs from fracture, but often leaves the underlying structures at increased risk for injury. There may be few if any external signs of trauma. Even bruising, petechiae, and tenderness may be absent.

Children who sustain thoracic trauma have decreased respiratory compensation. They have higher oxygen consumption per unit body mass and a smaller lung functional residual capacity. Younger children are diaphragmatic breathers due to horizontally aligned ribs and immature intercostal musculature. The pediatric mediastinal structures have a higher percentage of elastin and are more mobile than an adult’s, making them more prone to injury from acceleration, deceleration, and rotational forces. Injuries to the mediastinum can result in rapid impairment of cardiac output and can lead to rapid ventilatory and circulatory collapse, as seen with tension pneumothorax.

Traditionally, physical exam findings, mechanism of injury, and initial screening chest radiograph guided decision-making regarding further imaging and patient disposition. Improvements in CT quality, utility, diagnostic certainty, and availability led to increased use of CT for evaluating thoracic trauma. Recent studies in children scrutinized the use of screening CT scans for the initial evaluation.^21–24 It is estimated that children are exposed to a 100-fold higher radiation dose from CT compared with plain chest radiograph.²⁵ One study reported that despite their institution’s increasing CT use, there were similar types and frequencies of injuries found on CT compared to plain chest radiograph over the 4-year study period.²¹ In the same study, the few patients who needed emergent thoracic surgery had abnormal findings on chest radiograph and CT scout images that would have clarified the need for further imaging or surgery. They concluded that chest radiograph would not have missed a life-threatening injury that required immediate surgical intervention and remains sufficient as an initial screening tool.²¹ In another study of severely injured children with traumatic brain injury (TBI), systematic CT scans identified severe chest injuries in 42% of the patients, most of them pulmonary contusions and most missed on initial chest radiograph.²⁶ These chest injuries were associated with prolonged intubation, hypoxia, and worse outcomes. Another study evaluated the utility and cost–benefit analysis of CT compared with radiograph.²⁴ The study concluded that helical chest CT scan was highly sensitive and better than radiograph for identifying thoracic injury; however, chest radiograph still provided valuable clinical information at minimal cost.

Thus, researchers recommend the selective use of CT scan in evaluating injured children and that chest radiograph not be replaced by CT as a screening tool, given the better risk–benefit ratio of radiograph.^21,24,27 Chest CT scan is best used in severely injured patients with multiple trauma and severe TBI and those with high-energy impact mechanisms of injury.²⁷ Evidence-based protocols for CT use in pediatric trauma patients, developed by multidisciplinary groups, should be implemented to help guide trauma providers in their diagnostic decision making process.²¹

Priority for managing thoracic injury lies in the recognition of life-threatening injury and stabilization of the airway, breathing, and circulation. The unique pediatric anatomy places victims of thoracic trauma at increased risk for airway and respiratory compromise and subsequent hypoxia. Focus airway management on ensuring airway patency while protecting and immobilizing the cervical spine. Provide adequate oxygenation using 100% fraction of inspired oxygen (FiO₂) by face mask or bag-mask ventilation, initiate early rapid sequence intubation if appropriate, and maintain proper minute ventilation. (For discussion of rapid sequence intubation see Chapter 18.)

Physical signs of thoracic injury can be subtle in the child, even in cases of severe injury. Respirations may appear shallow rather than labored, and central cyanosis can be absent in cases of hemorrhagic shock because of the relative decrease in unsaturated hemoglobin. When shallow respirations are detected, use end-tidal CO₂ monitoring to assess the adequacy of ventilation. In non-intubated patients, use “side-stream” CO₂ monitoring by nasal cannula, and for intubated patients, “in-line” end-tidal CO₂ monitoring to monitor ventilatory function and detect early compromise. Assess the circulatory status immediately after stabilizing the airway and breathing status. With volume loss, the pediatric patient may become profoundly tachycardic in order to maintain appropriate cardiac output and perfusion. Children may remain in a state of compensated hypovolemic shock until up to 40% of their blood volume is lost. Initiate fluid resuscitation with two large-bore intravenous lines and the infusion of isotonic crystalloid solutions, such as normal saline or lactated Ringer’s. If you suspect major vessel injury and hemorrhagic shock, continue resuscitation with transfusion of donor blood products or by autotransfusion. Subtle findings of thoracic injury are often detected during the secondary survey.

Diagnostic studies and treatment will vary depending on the clinical situation. Check a baseline hemoglobin/hematocrit and send a type and screen. Obtain a chest radiograph to evaluate for a pneumothorax or hemothorax (Fig. 26-1). However, there are clinical situations that may dictate immediate treatment without a radiograph if the patient has clinical signs or symptoms of hypoxia and/or hypotension. Concurrent abdominal and thoracic trauma requires a special approach. If surgical management of an abdominal injury is necessary, manage chest injuries requiring tube thoracostomy before administering general anesthesia to the patient. The abdominal injuries are repaired first, and after the abdomen is closed a thoracotomy can be performed as necessary for other injuries and to irrigate the chest if it is contaminated with intestinal contents.

Research has focused on the development of best practices to aid the early diagnosis of pediatric thoracic injury and improvement of care, including cost-effectiveness. One study focused on the predictors of thoracic injury and developed a model that maximizes sensitivity and specificity for identifying children with thoracic injuries.²⁸ They noted several independent predictors of thoracic injury in this population, with the strength of association listed in decreasing order: abnormal chest findings on auscultation, hypotension, abnormal findings of the external thorax, and elevated age-adjusted respiratory rate. Abnormal findings on chest auscultation have the highest predictive value for thoracic injury; tachypnea is often present in patients with pulmonary contusions. When this prediction model is utilized, patients without any of these findings are at very low risk for having clinically significant thoracic injuries.

PULMONARY CONTUSION, LACERATION, AND HEMATOMA

Pulmonary injuries are the most common type of thoracic trauma in children. Children are particularly susceptible to pulmonary contusion despite few external signs of trauma. Pulmonary contusion can be caused by blunt trauma to the chest wall or by high-speed penetrating trauma, such as a gunshot wound. Injured capillaries bleed into the interstitial and alveolar spaces and lead to hypoxia and respiratory distress. Alveolar hemorrhage, edema, and consolidation lead to inadequate oxygenation, hypoventilation, and the development of a ventilation–perfusion mismatch. The majority of pulmonary contusions are detected on chest radiograph, but smaller areas of injury may only be diagnosed by chest CT.

Have a high index of suspicion so that a pulmonary contusion can be identified early. Initial symptoms range from minimal to severe respiratory distress and/or hypoxia. Tachypnea is the chief physiologic response to hypoxia. Tachypnea and retractions may be severe when pulmonary compliance is limited because of the injury. Prolonged respiratory distress can lead to respiratory fatigue and failure. Knowledge of the mechanism of injury may be the only early indicator of pulmonary contusion. The initial chest radiograph may not show the classic patchy infiltrate, and physical examination may not reveal signs of pulmonary consolidation. In the early stages of injury, abnormalities on blood gas analysis may not be diagnostic if the alveolar–arterial gradient is still normal. However, as the injured lung parenchyma collapses and becomes congested, gas exchange is impaired, hypoxia ensues, and injury becomes more evident. Providers should direct treatment toward preventing hypoxia and respiratory failure. Most cases require only supplemental oxygen and close monitoring. Patients may need to be intubated and ventilated with higher positive end-expiratory pressures (PEEP) of greater than 5 cm H₂O if the injuries have caused a decrease in lung compliance. Areas of contusion larger than 30% often require mechanical ventilation. Take additional measures, such as fluid restriction, early mobilization, and pain control to avoid worsening atelectasis. Early detection and treatment of secondary pneumonia may prevent further complications. Spontaneous resolution of pulmonary contusions is the usual course unless the injury is complicated by a more diffuse reactive process, such as acute respiratory distress syndrome (ARDS). Pulmonary lacerations are often associated with penetrating trauma, but may be the result of a rib fracture from blunt trauma. Lacerations of lung parenchyma are diagnosed by history, physical examination, and thoracic imaging. Pulmonary lacerations have a cavitary appearance on chest radiograph, but the extent is more visible on the chest CT. Surgical repair is necessary when the laceration is associated with ongoing bleeding or air leakage. Pulmonary hematoma is uncommon, is generally a self-limited injury, and rarely progresses to lung abscess.

PNEUMOTHORAX

Pneumothorax can occur spontaneously or from trauma. Spontaneous pneumothorax is caused by a ruptured bleb or small distal bronchiole that will easily seal itself and heal quickly. The air is reabsorbed over a few days often without intervention. At the most, they may require 100% FIO₂ by face mask and/or a small chest tube.

Pneumothoraces occur in one-third of pediatric thoracic trauma cases, and most are associated with other injuries and can compromise patient stability. A small, uncomplicated pneumothorax is often asymptomatic and may be small enough to miss detection by chest radiograph (Figs. 26-2 and 26-3). Even a small pneumothorax can quickly develop into a more serious tension pneumothorax. A tension pneumothorax puts pressure on and, if large enough, causes a shift in the mediastinal structures, which decreases cardiac filling and output (Fig. 26-4). An untreated tension pneumothorax may rapidly lead to cardiovascular collapse.

Treat small, isolated traumatic pneumothoraces with observation for at least 6 hours and a repeat chest radiograph. If there is no size increase, no underlying parenchymal injury, and the patient remains clinically stable, consider discharge to return in 24 hours for a repeat evaluation. Place a chest tube for a pneumothorax that is large enough to cause a potential complication, especially if the patient is intubated or will require transport by air ambulance, as changes in atmospheric pressure may cause an otherwise small pneumothorax to expand.

TENSION PNEUMOTHORAX

Tension pneumothorax occurs when the lung or airway develops a leak through a defect that acts like a one-way valve, allowing air to flow into the pleural cavity without a means of escape. As the amount of air increases, the pressure against the mediastinal structures shifts the mediastinum toward the opposite side, causing vascular compromise of the heart and great vessels. Cardiac decompensation ensues from mechanical impingement of blood flow and hypoxia from respiratory compromise. A tension pneumothorax may be caused by barotrauma from severe blunt compression of the chest cavity against a closed glottis, or rib fractures that puncture the lung tissue. Penetrating injuries, such as stab wounds, can cause a tension pneumothorax when the lung parenchyma is injured without a large enough chest wall defect to allow for spontaneous decompression.

Diagnose a suspected tension pneumothorax clinically. Patients with tension pneumothorax present with severe respiratory distress, decreased breath sounds, and hyper-resonance on the affected side. Subcutaneous emphysema may dissect superiorly into the neck or inferiorly into the abdomen and scrotal area. Contralateral tracheal deviation, distended neck veins from compromised venous return, a narrow pulse pressure, and hypotension will alert the provider to the severe decrease in cardiac output. If the tension pneumothorax is not expeditiously decompressed, cardiovascular collapse often ensues.