Epidemiology and prevention

Trauma is a leading cause of morbidity and mortality in children worldwide and is the leading cause of death for children in the United States. Thoracic injuries account for 4% to 13% of pediatric trauma admissions. Pediatric mortality from thoracic trauma is 15% to 25%, second only to brain injury mortality. Although the majority of published studies on traumatic injury have considered only adults, efforts to better characterize patterns of trauma in children have resulted in the creation of several national databases. These databases are the foundation for the majority of epidemiologic studies on pediatric trauma and include the National Pediatric Trauma Registry (established 1994), the National Trauma Data Bank, and the American College of Surgeons Trauma Quality Improvement Program (TQIP).

Thoracic trauma can be divided into blunt and penetrating mechanisms of injury. Blunt injuries account for the majority of pediatric chest trauma (≥85%) and include injuries incurred from motor vehicle collisions (MVCs), pedestrian accidents, falls, and nonaccidental trauma. Penetrating injuries, such as gunshot and stab wounds, are uncommon in the pediatric population, with most occurring in adolescents. While recent school shootings have sparked increased public attention to this issue, school violence and violence among juveniles overall are decreasing nationally, increasing the rarity of these injuries and associated institutional experiences.

Thoracic trauma may result in a diverse and potentially deadly pattern of injuries. Although mortality is only 5% overall for isolated thoracic injuries, the rate increases up to 20% for thoracoabdominal injuries and 40% for multisystem injury. ^, The most prevalent causes of injury vary by age group and have been described in detail in the United States using the National Trauma Data Bank. Infants and toddlers are often victims of falls, MVCs, and nonaccidental trauma. School-aged children 5 to 9 years old remain at risk for falls and MVCs and are also frequently injured as pedestrians struck by motor vehicles. Older children and teenagers (10–17 years old) are most frequently involved in MVCs but also are increasingly victims of accidental and nonaccidental penetrating trauma. ^, Obesity does not impact the severity of injury, mortality rate, or procedural outcomes in children. However, obese children are more likely to have rib and pelvic injuries.

Anatomic and physiologic considerations

The anatomy and physiology of the chest wall and thoracic viscera among children vary considerably compared with adults. The pediatric chest wall is more compliant owing to increased cartilage content with incomplete rib ossification. Rib angulation and morphology also change with normal development and are associated with increased fragility with aging and senescence. ^, Therefore, rib fractures are uncommon in children and indicate significant traumatic energy when present. The relative rarity of isolated rib fractures among children underscores the importance of considering additional intrathoracic injuries even in the absence of fractures. Because less kinetic energy is absorbed by the ribs, more energy is transferred to the internal organs. Pulmonary contusions are commonly present without rib fractures, with prevalence as high as 70% among children with known thoracic trauma.

In accordance with this theme of increased tissue compliance, the pediatric mediastinum and its contents are highly flexible and mobile. Therefore, patients can develop compressive physiology from tension pneumothorax or hemothorax at relatively low pleural pressures compared with adults. Decreased venous return may lead to shock and rapid death. In the context of the rarity of this condition as well as the decreased reliability of physical examination, physicians who treat injured or critically ill children must maintain a high index of suspicion in evaluation of any patient with thoracic injuries or who are mechanically ventilated and then develop sudden respiratory decompensation.

The smaller chest transmits breath sounds more readily. Even in cases of a large pneumothorax or effusion, breath sounds may seem equal. Pediatric patients are more vulnerable to developing hypoxia as their basal metabolic rate is higher, leading to greater oxygen consumption rate. Children also have a smaller functional residual capacity, which manifests as a rapid decline in oxygen saturation during endotracheal intubation even when the patient has been preoxygenated by face mask. The pediatric trachea is more compressible and narrow; therefore, children are more susceptible to profound respiratory distress with mucous plugging or aspiration of a small foreign body.

Children notoriously maintain normotension despite considerable blood losses. Pediatric patients may lose 30% to 40% of their intravascular volume before manifesting derangements in blood pressure, which can lead to diagnostic delays and additional morbidity. Even the relatively smaller thoracic volume among young children is sufficient to contain blood to effect hemorrhagic shock in these patients. Thus, the thoracic cavity should always be considered a potential source of unrecognized hemorrhage in differentiating causes of posttraumatic shock. Cardiac contractility is fixed in early life; therefore, heart rate must increase to maintain cardiac output in the face of diminished circulating volume. This tachycardia may be the first and only sign of hypovolemia prior to rapid decompensation after injury. However, heart rate is variable among children under normal physiologic conditions and is typically elevated among frightened children. ^,

Children have a relatively high body-surface-to-volume ratio, allowing for a high rate of radiant cooling. Therefore, pediatric patients can become hypothermic quickly, either outdoors or in the trauma bay. Hypothermia is common and deadly among severely injured patients. Early interventions to correct or prevent hypothermia are critical to prevent the lethal triad of hypothermia, acidosis, and coagulopathy. ^, Protocolized maintenance of normothermia should be considered in any patient with thoracic injuries requiring admission to an intensive care unit (ICU).

Initial resuscitation and diagnosis

Initial care of patients should follow the principles of Pediatric Advanced Life Support (PALS). First and foremost, the airway should be secured. Inability to maintain an airway or a Glasgow Coma Score of 8 or less should prompt orotracheal intubation. Patients with suspected cervical spine injuries or unknown cervical spine status should have manual in-line cervical stabilization maintained during intubation and a cervical collar placed promptly after intubation. If an adequate airway cannot be established with orotracheal intubation or is insufficient owing to maxillofacial or neck trauma, then a surgical airway should be established. Once an airway has been established, end-tidal carbon dioxide (CO ₂ ) and breathing should be assessed. The chest should be observed for symmetric rise and fall. The right and left chests should be auscultated to ascertain adequate airflow and the position of the endotracheal tube confirmed with a chest radiograph. Arterial oxygen saturation or pulse oximetry may be used to assess oxygenation. Arterial CO ₂ measurement or capnography may be used to assess ventilation.

Life-threatening conditions affecting airway, breathing, and circulation—such as airway compromise, tension pneumothorax, hemothorax, and cardiac tamponade—should be identified and addressed immediately with appropriate treatment. A child who loses vital signs in the trauma bay may require an emergent thoracotomy.

Circulation should be assessed by pulse, heart rate, and capillary refill. In a warm, well child, the capillary refill should be 2 to 3 seconds. The presence and character of central pulsations (i.e., carotid or femoral) should be assessed and described. Blood pressure must be assessed with an appropriately sized cuff in order to yield accurate measurements. Adequate intravenous access should be simultaneously established with 2 large-bore peripheral intravenous (IV) catheters. If peripheral access cannot be established in a severely injured patient, then intraosseous or central venous catheter (CVC) placement should be performed without delay. More volume can be given over a shorter period of time through a peripheral IV line than through a CVC owing to the increased resistance over the length of the central line. Intraosseous flow rates approach those of peripheral IV lines in adults and are generally preferred for rapid volume replacement compared with CVCs. An initial intravascular or intraosseous isotonic crystalloid bolus of 20 mL/kg should be given. If the patient’s vital signs do not improve, a second bolus should be given, followed by transfusion of blood products to approximate whole blood in a 1:1:1 packed red blood cell-plasma-platelet ratio.

Once the airway, breathing, and circulation have been addressed, the child should undergo a thorough physical examination to evaluate for injuries. The thoracic examination should include inspection of the patterns of bruises and abrasions that may raise concern for internal injuries. The chest should be palpated to look for rib tenderness, fractures, or subcutaneous emphysema. Careful examination of the back—including inspection and palpation of the thoracic spine—may raise concern for trauma to the osseous, ligamentous, or cord structures. Such patients should remain flat and be “log rolled” to allow examination prior to full characterization with advanced imaging.

A chest radiograph is the initial screening tool for blunt thoracic trauma. Computed tomography (CT) can be an important adjunct in the diagnosis of blunt or penetrating trauma. CT is the gold standard for detection and characterization of soft-tissue injuries of the lungs, pleura, heart, mediastinum, and its contents. However, in the pediatric patient, exposure to unnecessary radiation is a significant concern. Although dose-reduction technologies continue to improve constantly and chest CT exposes patients to less radiation than abdominal or head examinations, thoracic CT scans contain the radiation dose of about 150 chest radiographs. Therefore, the routine use of CT scanning is not justified unless there is adequate clinical concern. Most clinically useful information found on CT scans ordered for chest trauma can ultimately be correlated with findings on clinical examination and chest radiograph. Therefore, chest CT should be used selectively (i.e., for the evaluation of an abnormal mediastinal silhouette on chest radiograph) given the relatively low specificity of the finding and potentially deadly implications for missed injuries to the region. Exposure to radiation can be limited by lowering the radiation dose, avoiding redundant studies, limiting studies based on a risk/benefit profile, and using alternative technology, such as magnetic resonance imaging and ultrasonography.

The role of ultrasound in the pediatric trauma bay is controversial, as ultrasound appears to be less useful than in adult trauma patients. The reason for this lack of efficacy among children is unclear and has not yet specifically been the subject of study, although it has commanded considerable conjecture. The focused assessment with sonography for trauma (FAST) examination primarily assesses for abdominal injury, although the pericardium is also routinely evaluated for pathologic fluid that may herald tamponade. Additionally, bilateral anterior thoracic ultrasonography may be added to the traditional four views to evaluate for pneumothorax or hemothorax (the so-called extended FAST , or eFAST ). In one study, the sensitivity of FAST for detecting injuries requiring operation or blood transfusion was only 87%. The sensitivity and specificity for detecting pathologic free fluid were 50% and 85%, respectively. The sensitivity of FAST is not sufficient to forego other imaging tests when there is clinical suspicion to warrant investigation; FAST has the greatest sensitivity and specificity in adults when used in the context of hemorrhagic shock after blunt abdominal or transthoracic penetrating injuries. ^,

Chest wall injury

The elasticity of the ribs in small children protects against fractures, even in cases of severe injury. Therefore, rib fractures should be considered a marker of significant traumatic energy and should prompt further evaluation of the underlying thoracic and abdominal viscera. Isolated rib fractures without associated injuries are found in a minority of children. Rib fractures in children are associated with higher rates of brain injury, hemothorax/pneumothorax, and liver injury. Higher rib fractures are not associated with great vessel injury in children; in isolation, without further concern, on chest radiograph they do not warrant aortography. ^, Lower fractures are associated with liver, spleen, and diaphragm injury.

Most children ages 3 years and younger with rib fractures have been abused; abused children tend to have more rib fractures than accidently injured children. Therefore, any young child who presents with rib fractures should raise a concern for a nonaccidental traumatic mechanism. However, accidently injured children are more likely to have internal thoracic injuries than abused children (56% vs. 13%). This is likely due to the difference in mechanism of injury. Abuse is usually performed over a longer duration of time from manual chest squeezing or a crush mechanism. Accidental trauma tends to be a single high-energy event of short duration.

In most cases, rib fractures are treated nonoperatively. However, admission may be required for pain control if multiple fractures are present. The goal should be to encourage pulmonary hygiene and prevent atelectasis and pneumonia. Multimodal analgesia in the form of nonsteroidal antiinflammatory drugs, narcotics, and neuraxial anesthesia may be needed. Thoracic epidural analgesia has a controversial role in children, and its outcomes have not been rigorously described as in adults. It is unusual for children with isolated rib fractures to require ventilatory assistance.

In rare cases, multiple ribs in a single area may be fractured, producing a flail chest. Specifically, this requires fractures of multiple contiguous ribs with at least 2 points of fracture per rib, or fracture of the sternum, or dislocation of rib heads. Flail chest results in paradoxical respiratory movement in which the thoracic wall over the flail segment collapses during inspiration, impeding ventilation of the lung.

The medial physis of the clavicle does not close until 23 to 25 years of age. Falls from trampolines are associated with fracture of the clavicle; falls can lead to posterior sternoclavicular fracture-dislocations in children. This injury can be associated with dysphagia, dyspnea, and brachiocephalic compression. Children with clavicular dislocations should be evaluated for injury to the esophagus and great vessels.

Sternal fractures, although rare, are usually associated with blunt traumatic injuries. They can result from MVCs, flexion-compression injuries, or direct blows. They are classically, but rarely, associated with cardiac injury. In fact, blunt myocardial injury is much more rare than other associated injuries; substernal hematoma and pulmonary contusions are most common. In a 16-year case series of all radiologically confirmed sternal fractures at a pediatric level 1 trauma center, only a single patient had cardiac contusion. ^, Given the rarity of blunt myocardial injury, telemetry, cardiac enzyme evaluation, and echocardiography are typically reserved for adult patients with screening electrocardiogram abnormalities. There are insufficient data to provide more detailed guidance among children. Ultrasound has a high sensitivity and specificity in the diagnosis of sternal fractures, especially among young, thin patients. ^, Scapular fractures are uncommon in children, as a significant amount of force is required to fracture the scapula. A careful neurologic and vascular examination should be performed, as axillary artery and brachial plexus injuries may be present.

In rare cases of chest trauma, an intercostal hernia may form, resulting in lung herniation. Most hernias occur at a site of previous injury and are commonly seen at the anterior parasternal border because the cartilaginous junction to the sternum is absent. Most are experienced after blunt trauma, particularly after multiple rib fractures or chondrocostal dislocation. The hernia should be treated by direct surgical repair and may require mesh placement. ^, Thoracoscopic hernia repair has been described.

Lung and airway injury

Pneumothorax (air in the pleural space) and hemothorax (blood in the pleural space) can both lead to respiratory compromise and subsequent cardiovascular collapse. Occult pneumothorax is the least severe of these entities. It is defined as air in the pleural space seen on CT but not visible on chest radiographs and without impaired ventilation or oxygenation. Occult pneumothorax can be safely observed and does not necessitate tube thoracostomy. Careful consideration should be given to the possibility of pneumothorax expansion after beginning positive-pressure ventilation; these patients may benefit from tube thoracostomy prior to intubation. Minor pneumothorax produces mild clinical symptoms, including tachypnea, distress, and decreased oxygen saturation. Pneumothorax may be suspected on physical examination when bruising or rib fractures are evident on the chest wall. Asymmetry in breath sounds or chest wall movement should also raise suspicion. Tension pneumothorax occurs when an injured tissue (either lung parenchyma or chest wall) forms a one-way valve, allowing air to enter the pleural space and preventing air from escaping. Tension pneumothorax results in rapid respiratory distress with distension of the affected side, contralateral displacement of mediastinal structures, and decreasing venous return with rapid decompensation and shock. Tracheal deviation may be seen with tension pneumothorax, as the tension in the air-filled side leads to compression of the healthy lung and deviation of the trachea away from the side of the pneumothorax. Any patient with a suspected pneumothorax and signs of respiratory or cardiac decline should receive immediate needle decompression of the chest cavity. Needle decompression can be performed by placing an angiocatheter into the second intercostal space at the midclavicular line. If a pneumothorax is encountered, the clinician should hear an immediate rush of air as soon as the pleural space is entered. At this point, the needle should be removed but the catheter left in place while the patient is prepared for emergent tube thoracostomy. The patient should be placed in the supine position with the arm in complete abduction. This position widens the intercostal spaces, facilitating placement of the tube. Tube thoracostomy should be performed by inserting an intercostal tube into the fourth or fifth intercostal space, in the midaxillary line. At this level, there is little risk of injury to the long thoracic nerve. A chest tube that is placed too low may inadvertently be placed below the diaphragm, with resultant injury to the liver, spleen, or intestines. If urgency allows, ultrasound evaluation during the procedure may help prevent subdiaphragmatic placement. Careful attention should be given to avoid the neurovascular bundle, which runs directly below each rib. A chest tube that penetrates the intercostal musculature directly above the fourth or fifth ribs has less chance of causing an intercostal arterial laceration. An adequately large tube should be placed to facilitate drainage of air, fluid, and blood. The tube should be connected to water seal drainage and suction to facilitate reexpansion of the lung ( Fig. 119.1 ).

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