AUTHOR INFORMATION	Section 1 of 6
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Author: Charles N Paidas, MD, Associate Professor of Surgery, Pediatrics, Critical Care Medicine, Oncology and Anesthesia, Johns Hopkins University School of Medicine, Director of Pediatric Trauma, Johns Hopkins Hospital

Charles N Paidas, MD, is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Association for the Surgery of Trauma, American College of Surgeons, American Pediatric Surgical Association, Association for Academic Surgery, and Society of University Surgeons

Editor(s): Daniel S Schwartz, MD, FACS, Clinical Assistant Professor of Cardiothoracic Surgery, New York University School of Medicine; Consulting Staff, Department of Surgery, Division of Thoracic Surgery, North Shore University Hospital/Long Island Jewish Medical Center; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Jonah Odim, MD, PhD, MBA, Senior Medical Officer, Transplantation Immunology Branch, Division of Allergy, Immunology, and Transplantation, National Institute of Allergy and Infectious Diseases, National Institutes of Health; Daniel Rauch, MD, FAAP, Director, Pediatric Hospitalist Program, Associate Professor, Department of Pediatrics, New York University School of Medicine; and John Kupferschmid, MD, Director of Congenital Heart Surgery, Department of Surgery, Methodist Children's Hospital at San Antonio

Disclosure

	INTRODUCTION	Section 2 of 6
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In children, thoracic trauma should be synonymous with multisystemic injury. Multisystemic injury is found in more than 50% of children with thoracic injuries, partly because 90% of childhood thoracic traumas are blunt injuries, including those due to pedestrian accidents and motor vehicle collisions. The small size and proximity of the chest to other systems (eg, head, abdomen, extremities) also contribute. The epidemiology of thoracic trauma indicates that associated systemic injuries occur in the following sequence: (1) CNS, (2) soft tissue, (3) skeleton, and (4) abdomen. Moreover, the younger the child, the more likely that the abdomen is the associated compartment.

The incidence of childhood thoracic trauma is well below that of neurologic, musculoskeletal, and abdominal trauma. However, the mortality rate is high in children with thoracic injury in association with injury to other systems. Mortality rates of isolated pediatric thoracic injury approach 5%, but associated abdominal injury elevates this rate to 20%. The mortality rate of childhood thoracic injury in association with head injury approaches 35% (see Image 1). This multisystemic association is 1 of, if not the only, distinctions of childhood thoracic injury (Reilly, 1992). Salient features that differentiate childhood from adult thoracic trauma are listed below and discussed throughout the text.

Key characteristics of childhood thoracic trauma are the following:

• Multisystemic injury is present in more than 50% of childhood thoracic injuries.

• Rib fractures are rare and indicate a direct blow to the chest and extreme force.

• The thoracic cage is cartilaginous, and the chest wall is extremely compliant.

• Pulmonary contusion is common.

• The mediastinum is not fixed; therefore, tension pneumothorax is poorly tolerated.

• Less than 15% of cases of childhood thoracic trauma require thoracotomy.

A critical diagnostic challenge in children with thoracic trauma is the possibility of a life-threatening injury. An essential step in the treatment of a child with thoracic injury is to determine whether the injury is life threatening, and, if so, decide how it can be quickly diagnosed and treated. Below are the most common immediate life-threatening thoracic injuries and potential life-threatening thoracic injuries.

• Immediate life-threatening thoracic injuries
  • Airway obstruction and injury

  • Lung and chest wall injuries

  • Open pneumothorax

  • Tension pneumothorax

  • Hemopneumothorax

  • Flail chest

  • Widened mediastinum/aortic dissection

  • Cardiac tamponade

• Potential life-threatening thoracic injuries
  • Pulmonary contusion

  • Ruptured tracheobronchial tree

  • Ruptured diaphragm

  • Esophageal perforation

  • Myocardial contusion

A child who is unstable has vital signs but clear signs or symptoms of cardiac or respiratory compromise. Poor skin perfusion (ie, capillary refill >2 sec), tachycardia, abnormal chest wall excursions, obvious mental status changes, and, possibly, hypotension all characterize instability in a child; a search for immediate life-threatening injuries is warranted (see Immediate Life-Threatening Injuries). If injuries are undetected or if diagnosis is delayed, these children may become agonal.

The stable child (ie, normal vital signs, adequate ventilation and oxygenation, normal capillary refill, adequate urine output) with thoracic injury from either a blunt or penetrating cause can be evaluated more thoroughly than others and with the added advantage of time. Injuries in stable children are potentially life threatening, but the survival rate is generally improved (see Potential Life-Threatening Injuries).

	IMMEDIATE LIFE-THREATENING INJURIES	Section 3 of 6
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Injury to the airway

Airway injuries may be the result of oropharyngeal trauma, a foreign body, or pathology directly within the thorax leading to a shift of the tracheobronchial tree. The 2 hallmarks of airway injury include obstruction and/or subcutaneous emphysema.

Oropharyngeal trauma is typically the result of a crush injury or direct blow. The resulting tracheal mucosal edema may be insidious, and breath sounds must be closely monitored.

Inspiratory stridor is the hallmark of airway obstruction at or above the level of the vocal cords. Blood, mucus, vomitus, teeth, or other foreign bodies may cause the stridor. This is a clinical diagnosis and must be emergently recognized and treated with removal of the obstruction. Other signs and symptoms of airway obstruction include agitation, diaphoresis, chest wall retractions, asymmetry of respirations, cyanosis, and, ultimately, bradycardia associated with severe hypoxemia.

Expiratory stridor is typically the result of pathology below the cords. Children with blunt trauma who have expiratory stridor should be evaluated for a foreign body aspiration (see Image 2). Diminished breath sounds, wheezing, and loss of volume depicted on plain chest radiograph may not be present. A high index of suspicion is imperative. Objects may not be radiopaque, and bronchoscopy should be performed early to avoid pneumonia.

Subcutaneous emphysema can result from tracheal disruption in the neck or thorax (see Image 3). Any positive pressure during expiration makes subcutaneous emphysema progress. If subcutaneous emphysema is unrecognized after intubation, it can also be worsened by positive pressure from mechanical ventilation.

Standard management begins with head positioning, suctioning, in-line cervical spine stabilization, and administration of supplemental oxygen. Obviously, obstruction above the vocal cords must be recognized and removed. Intubation may be necessary, and, if not possible, needle cricothyrotomy or tracheostomy is indicated. Control of the airway in an unconscious patient must always be the first management step.

Lung and chest-wall injuries

Both simple and tension pneumothorax are not well tolerated in children because of the lack of fixation of the mediastinum. The difference in these problems is time—an untreated simple pneumothorax eventually leads to a tension phenomenon (see Image 4). Pneumothorax is a clinical diagnosis and does not require radiographic confirmation for treatment.

Performing needle decompression through the second intercostal space at the level of the midclavicular line, followed by tube decompression, or simply proceeding to tube decompression, is the treatment of choice. Chest radiography should follow to confirm tube position and reinflation of the lung. Tension pneumothorax is not well tolerated in children because not only is a shift of the mediastinum present but also kinking of the inferior vena cava resulting in decreased venous return. An open pneumothorax associated with a sucking chest wound causes pathophysiology because a path of less resistance is created for tracheobronchial air. To prevent this airflow, the wound must be covered and tube decompression must follow.

Bleeding from within the chest is rare in children, mainly because of the low incidence of rib fractures (see Image 5). However, chest bleeding can be an insidious cause of life-threatening injury. Hilar bleeding is usually not compatible with life. Bleeding is otherwise typically from an intercostal vessel or lung parenchyma. Regardless of the source, the chest must be evacuated to avoid atelectasis, ventilation-perfusion mismatch, fibrothorax, and a restrictive lung. Treatment involves tube decompression. Initial hemorrhage of more than 20 mL/kg or continued blood loss of more than 2-3 mL/kg/h for 3 consecutive hours may be an indication for open thoracotomy. Moreover, inability to adequately drain the chest and re-expand the lung is an additional criterion for thoracotomy. The pathology is typically an intercostal vessel or vessels, parenchyma, or chest wall. Lobectomy is far less common than stapling of bleeding or simple wedge resection.

Flail segments are defined as 2 or more ribs fractured in 2 or more places. The flail segment results in ventilation-perfusion mismatch, atelectasis, and progressive shunting. In general, patients with an unstable chest wall should be treated with positive pressure and pain control.

Air embolism is a potential complication of penetrating lung injury. Seizures and sudden cardiac arrest may be the only clues to this near fatal event. Treatment involves thoracotomy, clamping the hilum, and aspiration of air from the left ventricle and aorta.

Widened mediastinum and aortic disruption

These are rare injuries in children. The typical mechanism, like in adults, is a rapid deceleration injury—either in a motor vehicle passenger involved in a collision, a pedestrian struck, or someone who fell from a height. Suspicion of this injury in a stable patient may only come from a chest radiograph depicting a widened mediastinum (see Image 6). Criterion for mediastinal pathology includes straightening of the mediastinal borders with loss of the anteroposterior (AP) window, a mediastinum greater than the diameter of the hemithorax, and a right shift of an orogastric tube off the vertebral column.

Radiographic signs of disruption of the aorta, typically at the ligamentum arteriosum, include the widened mediastinum, left pleural effusion, apical capping, depression of the left main bronchus, rightward shift of an orogastric tube (off the vertebral column), and fractures of the first or second rib or scapula. Upper-extremity hypertension, interscapular murmurs, and diminished or absent pulses in upper or lower extremities are common physical signs. Aortography is the diagnostic procedure of choice (see Image 7). If a contained hematoma is identified, urgent left thoracotomy, aortic cross-clamping, and extension of the thoracotomy into the right chest (clam shell incision) to create a potential for bypass, is necessary. The operating surgeon must decide whether to perform end-to-end repair of the descending aorta, to use an autologous graft, or to use tube graft material made of Dacron (DuPont, Wilmington, DE).

In the best of cases, ischemia of the spinal cord during cross-clamping of the descending aorta is still possible. Therefore, the mortality and morbidity rates are high with this injury. Hemodynamic management should include avoidance of hypertension and beta-blockade if children are treated nonoperatively. Great vessel injury in children is occasionally repairable after penetrating trauma but usually fatal after blunt trauma.

A diagnostic dilemma may result when clinicians encounter a stable transected aorta and associated life-threatening abdominal pathology. In patients with a stable thoracic hematoma, treatment includes evaluation and repair of the abdominal injuries first, followed by a left thoracotomy for management of the transected aorta. As an alternative, the child with a rapidly expanding hematoma of the chest and concomitant abdominal pathology should undergo a thoracotomy before anything else.

Penetrating injury to the mediastinum can occur without a pneumothorax. Therefore, a stab wound between the nipples can injure the heart or great vessels without damaging either pleural space. Moreover, because the abdomen begins at the nipple line, pathology below the diaphragm should be ruled out when a stab wound occurs at this level.

Cardiac tamponade

The classic signs of cardiac tamponade in children are no different than those in adults. Muffled heart sounds, distended neck veins, and hypotension comprise the diagnostic triad (ie, Beck triad) that defines cardiac tamponade. Subxiphoid needle pericardiocentesis is the treatment of choice. Directing a catheter at a 45° angle toward the left scapula and using a Seldinger technique to maintain the catheter in the pericardial space facilitates continued aspiration of the pericardial sac before emergency left thoracotomy or median sternotomy (depending on the associated pathology). Aspiration of as little as 5 mL of nonclotted blood relieves the tamponade in infants. Time constraints often do not permit application of an alligator clip to avoid puncture of the heart muscle. Radiographic or echocardiographic testing is not needed to make the diagnosis.

Specific injuries and surgical strategies for the heart and great vessels

In unstable children, the mortality rate from heart and great vessel injury approaches 100%. In stable children, 2-dimensional echocardiography should be used to ascertain whether blood is in the pericardial sac. If any question about the diagnosis exists and the patient is stable, the subxiphoid pericardial window is the definitive diagnostic procedure. If the result is positive, immediate operation and cardiorrhaphy is indicated. In hemodynamically unstable children, a pericardiocentesis should be performed. If this test is positive, emergency thoracotomy or sternotomy for repair of the heart is indicated.

Time is obviously critical for survival in these cases. A bleeding heart is controlled with digital pressure and suture of any lacerations with pledgetted mattress Tevdek or polypropylene sutures. A Foley catheter can be used to control hemorrhage for larger lacerations. Horizontal mattress sutures underneath coronary vessels are used to repair lacerations in proximity to the coronary vessels. Lateral placement of vascular clamps followed by continuous or interrupted suturing is indicated for injuries to the atria and cava. Ventricular lacerations should be closed with simple pledgeted sutures. The pulmonary artery and aorta should both be repaired with interrupted horizontal mattress sutures reinforced with pledgets.

Operative approaches to treat specific thoracic injuries are as follows:

• Cardiac tamponade - Left anterior or anterolateral thoracotomy (fifth intercostal space)

• Injury to the heart, great vessels, or pulmonary hilum - Median sternotomy and extension into the neck

• Injury to the aorta and esophagus - Posterolateral thoracotomy

• Injury to the ascending aorta - Median sternotomy (cardiopulmonary bypass is usually required to repair a blunt injury; penetrating injuries can be repaired without bypass.)

• Injury to the descending thoracic aorta - Left posterolateral thoracotomy (fourth and fifth intercostal spaces)

• Injury to the aortic arch - Median sternotomy with extension into the neck for great vessel exposure

• Injury to the innominate artery - Median sternotomy with right cervical extension if necessary

• Subclavian artery injury - Cervical extension of median sternotomy for right subclavian artery injury or a supraclavicular approach for left subclavian artery injury (Proximal control of either vessel is best via an anterolateral thoracotomy above the nipple.)

• Carotid artery injury - Right cervical incision for right carotid artery injury or, like for innominate artery injury, median sternotomy with left cervical extension for left carotid artery injury

• Pulmonary artery - Respective side thoracotomy for hilar control

	POTENTIAL LIFE-THREATENING INJURIES	Section 4 of 6
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Pulmonary contusion

Pulmonary contusion is the most common thoracic injury in children and represents a defining contrast between children and adults. In contrast to rib fractures in adults after blunt trauma, the kinetic energy of blunt chest trauma is transmitted to the compliant chest wall in children. Thus, both pulmonary contusion and hemorrhage are far more common than pneumothorax (Allen, 1997). Typical chest radiographic findings include multiple opacifications corresponding to intraparenchymal hemorrhage (see Image 8). Hypoxia from shunting and ventilation perfusion mismatch, in addition to radiographic findings, is characteristic of pulmonary contusion. Successful treatment involves aggressive pulmonary toilet and pain management. Resolution of the contusion within a few days is not uncommon (see Image 8). Sequelae of pulmonary contusion include pneumonia and posttraumatic pseudocysts, both of which should resolve with antibiotics and time.

Pulmonary contusion from a car or truck rollover injury in children is a common phenomenon. Again, because of the elasticity of the chest wall, transfer of kinetic energy by means of this mechanism commonly results in contusion rather than multiple rib fractures. A simultaneous phenomenon results when the intrathoracic pressure suddenly rises against a glossed glottis or compressed tracheobronchial tree. This is called traumatic asphyxia.

Because the superior vena cava (SVC) has no valves, the rise in intrathoracic pressure induced by the injury results in a sudden rise in right atrial pressure that is transmitted retrograde up through the SVC and points proximal into the neck and head. Children typically present with subconjunctival hemorrhage and petechiae of the chest, shoulders, and head, which cause them to have a bronzed discoloration (see Image 9). CNS and pulmonary dysfunction can be associated with traumatic asphyxia, but this is a rare occurrence. These children should be monitored in the ICU for 24 hours because of the potential for airway obstruction secondary to venous hypertension and petechiae generated under the tongue and oropharynx (see Image 9). Despite the cutaneous manifestations, most of the petechiae disappear in a few weeks.

Ruptured tracheobronchial tree

Ruptured tracheobronchial tree can be partial or complete, and they are relatively uncommon in children because of the elasticity of the chest wall. Subcutaneous air solely in the neck may indicate pathology in the trachea. A persistent air leak after decompression of a pneumothorax is suggestive of a bronchial tear. Typical points of disruption include fixed points such as the carina or segmental branches of the bronchus. These injuries are commonly diagnosed with the aid of a bronchoscope, and the injury's location determines the subsequent treatment approach. However, bronchoscopy frequently leads to an underestimation of the magnitude of the injury.

Delays in treatment can be life threatening because both ventilation and oxygenation can be effected. Most tracheobronchial injuries can be repaired primarily, provided that the suture line is tension free. Because of the mechanisms of these injuries, blast effect and reduced blood flow to the perimeter of the injury must be looked for and, if necessary, a widened excision must be performed. The trachea should be repaired by means of a median sternotomy, whereas each mainstem bronchus and its branches can be repaired from respective chest cavities. Tears of the basilar bronchial tree can be managed with high-frequency and low-pressure ventilatory settings; however, if a persistent pneumothorax is present, a thoracotomy may be required.

Ruptured diaphragm

An elevated left hemidiaphragm indicates a ruptured diaphragm until proven otherwise. Aids to this diagnosis include the position of an orogastric tube on plain radiograph (see Image 10). In addition, bowel sounds in the chest are suggestive of the injury. Diaphragm injuries are far more common on the left than on the right because of the protection of the liver; they can go unnoticed, especially in an intubated patient. Moreover, relatively common injuries to the liver obscure suspected diaphragmatic injuries on the right side (Sola, 1994).

An important lesson for management of a ruptured diaphragm is the possibility of associated abdominal pathology. The abdomen begins at nipple level in children. Therefore, a high index of suspicion is warranted after blunt or penetrating injury. For penetrating injuries at or below the nipple, and no apparent pathology on CT of the abdomen, laparoscopy is helpful.

Esophageal perforation

Air present in the prevertebral space on a lateral neck image is abnormal. Typical for penetrating neck trauma but rare after blunt neck injury, this finding must always be evaluated. Esophagography with water-soluble contrast and esophagoscopy may both be required. Neck exploration should be performed urgently to avoid continued leak of saliva.

Management of esophageal injury in the mediastinum is dependent on making the diagnosis and determining if a contained or free passage of contrast into the pleural space exists. In the absence of systemic pathology, a contained leak may be managed with orogastric decompression, antibiotics, and nothing by mouth (NPO) status. A leak into the pleural space, mediastinitis, and hydropneumothorax all require open repair.

In general, the upper and mid esophagus are best approached through the right side of the chest, whereas the lower third of the esophagus and the esophagogastric junction are best approached through the left side of the chest. Some pleural or intercostal muscular covering should accompany debridement and primary repair. Wide drainage of both the mediastinum and pleural space is mandatory. Gastrostomy is also helpful. If inflammation is substantial and if the injury is extensive, cervical esophagostomy is necessary, followed by eventual esophageal replacement. Surgeons should attempt to use the native esophagus in a growing child by all means possible.

Myocardial contusion

Secondary to blunt cardiac forces, the pathology involves reduction in blood flow to a contused cardiac muscle followed by ischemia. The hallmark of myocardial contusion includes ischemic changes or atrial or ventricular premature contractions or wall motion abnormalities during echocardiography. The right ventricle is most frequently affected. However, other than the arrhythmias, creatine kinase–MB (CK-MB) fractions are elevated in less than 5% of cases, and troponin, as well as echocardiography, is of little help. Patients with ectopy or ischemic changes require monitoring in the ICU for 24 hours after injury. Echocardiography is required for any new onset of a murmur. If surgery is required for another reason in cases of ICU monitoring of suspected myocardial contusion, procedures should not be postponed; myocardial function should be monitored by using standard methods during surgery.