Pulmonary Contusion, Laceration, and Hematoma
Pulmonary injuries are the most common type of thoracic trauma in children as they 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 to the chest. Injured capillaries bleed into the interstitial and alveolar spaces leading 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.
A high index of suspicion is necessary to identify pulmonary contusion 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 clinical 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. Treatment is directed 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, generally a self-limited injury, and rarely progresses to lung abscess.
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 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. 25-2 and 25-3). 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. 25-4). An untreated tension pneumothorax may rapidly lead to cardiovascular collapse.
A chest x-ray demonstrating a pneumothorax (white arrow) and overlying subcutaneous emphysema (black arrow), which can be seen tracking up to the neck.
Ultrasound: Normal lung movement on Doppler (A) and M mode (B) demonstrating the absence of pneumothorax (the “seashore sign”).
A. A chest x-ray of a 12-year-old boy who was struck by a car. This hastily done, poor-quality film was taken when the child's mental status began to deteriorate. Note the left costophrenic angle, which is surprisingly deep (white arrow). This is an example of a deep sulcus sign seen in an anterior pneumothorax. B. The chest CT scan of the same patient clearly demonstrates the anterior pneumothorax. (Reproduced with permission from Shah BR, Lucchesi M: Atlas of Pediatric Emergency Medicine. McGraw-Hill, 2006. Photo contributor: Michael H. Siegel, MD)
Treatment for small, isolated traumatic pneumothoraces include observation for at least 6 hours with a repeat chest radiograph. If there is no size increase, no underlying parenchymal injury, and the patient remains clinically stable, he or she may be discharged to return in 24 hours for a repeat evaluation. A chest tube should be placed when a pneumothorax 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. (See Needle Thoracostomy and Tube Thoracostomy sections below.)
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.
The diagnosis of a suspected tension pneumothorax is made 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.
Treatment for a suspected tension pneumothorax should never be delayed to obtain a chest radiograph. A tension pneumothorax can be relieved by needle thoracostomy. To perform this procedure, a needle catheter is attached to a valve or three-way stop cock and inserted into the pleural cavity via the second intercostal space at the midclavicular line. (See Needle Thoracostomy section below.) In adolescents and obese patients, a longer catheter is needed or move quickly to tube thoracostomy. Diagnosis of tension pneumothorax in children may be complicated by false transmission of breath sounds. This can confuse the clinical diagnosis; however, uncertainty as to the side of the tension pneumothorax should not prohibit initiation of empiric treatment if the patient is deteriorating. Decompression of the other side should be done if immediate improvement is not seen with the initial needle or tube thoracostomy. Definitive treatment is accomplished using a large-caliber (appropriate for age) thoracostomy tube placed laterally and directed posteriorly to allow drainage of a concurrent hemothorax. (See Tube Thoracostomy section below.) Table 25-2 outlines appropriate chest tube sizes for trauma patients.
TABLE 25-2Chest Tube Sizes ||Download (.pdf) TABLE 25-2 Chest Tube Sizes
Chest Tube Size (Fr)
Hemothorax and Massive Hemothorax
The mechanism for hemothorax is similar to that for pneumothorax. Rib fractures, penetrating trauma, crush injuries with chest compression, or shearing forces can cause major vascular injury. Massive hemothorax is rare in children and when present is usually a result of forceful mechanisms, such as high-speed motor vehicle crashes, falls from great height, or high-powered or close-range gunshot wounds. Blunt injuries and gunshot wounds typically cause bleeding from lung parenchyma and deep vascular structures. Stab wounds more often cause injury to the intercostal vessels. Injury to the intercostal or internal mammary vessels or lung parenchyma may result in significant bleeding, which is difficult to quantify on chest radiograph. A minimum of 10 mL/kg of blood is often necessary to be visualized. Providers should assume that any abnormal fluid collection in the traumatic setting is blood.
Clinical findings vary in severity and involve both respiratory and circulatory systems. Auscultation of the chest often reveals decreased breath sounds and dullness to percussion on the affected side with or without obvious respiratory distress. Pneumothorax may also be present and worsen the degree of respiratory distress. Large collections of hemothorax may compromise cardiac output similar to a tension pneumothorax.
Each hemithorax can hold 40% of a child's blood volume, enough blood loss to lead to decompensated hemorrhagic shock. Immediate drainage and observation for the volume and rate of ongoing blood loss is necessary. In cases where bleeding is uncontrolled or ongoing losses are significant, definitive surgical repair may be necessary. Begin fluid resuscitation with crystalloid in the field. Preparation for transfusion should begin immediately and blood be given as the clinical situation warrants. Critical patients may require immediate transfusion with O-negative blood, whereas more stable patients may be able to wait for type-specific or cross-matched blood. Both vital signs and the amount of output from the chest tube should be taken into account when deciding the need for immediate transfusion. Hemoglobin and hematocrit may not be useful initially because rapid blood loss does not allow for equilibration and these tests may not accurately reflect current blood volume. Evacuation of a hemothorax is performed to prevent delayed complications due to fibrosis, empyema, and pneumonia and sepsis. Collections of blood serve as culture media for bacteria and should be promptly drained.
Place thoracostomy tubes as soon as massive hemothorax is suspected. A large-caliber (approximately as wide as the intercostal space) tube should be placed. (See Tube Thoracostomy section below.) Consider using an autotransfusion chest tube collection system, as this may be the most rapidly available source for blood transfusion. Take a chest radiograph soon after chest tube placement to confirm the position and to ensure reexpansion of the lung.
In certain circumstances, an emergency thoracotomy may be necessary to control massive hemorrhage. The decision to proceed with a thoracotomy will generally be made by the consulting surgeon. Guidelines include initial evacuated blood volume exceeding 10 to 15 mL/kg or continued blood loss exceeding 2 to 4 mL/kg/h. Continuous air leakage with complicated oxygenation and ventilation requirements may be another reason to do so.
An open pneumothorax (“sucking” chest wound) is created when the chest wall is sufficiently injured to create bidirectional flow of air through the wound. This is most commonly associated with massive penetrating trauma, as seen with gunshot wounds. The normal expansion of the lung is impossible due to the loss of negative intrathoracic pressure and the normalization of pressures between the chest cavity and atmosphere. Inability to generate the negative pressure necessary to expand the lung compromises gas exchange and leads to hypoxia and hypercarbia. The compliant mediastinum allows for collapse of both lungs on inspiration, resulting in ineffective, paradoxical breathing.
Management of an open pneumothorax depends on the size of the chest wall defect and respiratory status. Small injuries, such as knife or gunshot wounds, can be treated by covering the chest wall defect with sterile petroleum dressing and placing a thoracostomy tube through a fresh incision. Size and location of the chest tube will depend on the extent of underlying injury. In general, a large-caliber tube placed laterally and directed posteriorly should be used, as an underlying hemothorax may be present. Small chest wall defects will seal and heal spontaneously and generally do not require surgical repair.
Prehospital treatment of a sucking chest wound may consist of placing a petroleum dressing with only three sides taped to create a flutter valve to allow for ongoing chest decompression while eliminating the sucking component of the chest wound. This should be converted to a sealed dressing with thoracostomy tube placed as soon as possible. Patients who are not spontaneously breathing or who have chest wall defects too large to adequately seal (such as in a blast injury) will require intubation and ventilatory support. Large wounds often require urgent thoracotomy to repair the chest wall defect and underlying injuries.
Traumatic Tracheal and Bronchial Disruption
Traumatic tracheal and/or bronchial disruption is rare in children. Airway injury is more frequently seen in penetrating trauma, but high-speed, blunt injury may place significant shearing forces on the tracheal tree to generate a tear. In cases of crush injuries, severe compressive forces transmitted against a closed glottis may also disrupt the tracheobronchial tree. Although infrequent, these injuries carry a high mortality rate. A third to half of these patients die within the first hour after injury. Most injuries occur in the distal trachea or proximal bronchi. If the injury occurs low in the bronchial tree, air rupture into the pleural space may lead to tension pneumothorax. Diagnosis of airway injury is made both clinically and radiographically (Fig. 25-5). Symptoms range from mild respiratory distress to respiratory arrest. Consider early bronchoscopy if there are concerns for tracheal/bronchial disruption. Chest CT allows for more definitive visualization and location of the injury. Treatment is variable and based on the specific lesion, stability of the patient, and other associated lesions.
This 13-year-old child was hit by a car. The AP chest x-ray demonstrates an obvious left-sided pneumothorax, but the position of the left lung is peculiar. Rather than collapsing toward the hilum, the lung seems to have fallen to the dependent portion of the thorax. This is called the “fallen-lung sign.” This is an extremely rare finding on x-ray, but when present, the abnormal position of the lung, together with the left-sided pneumothorax, is highly suggestive of rupture of the tracheobronchial tree. This was confirmed on a subsequent CT scan. (Reproduced with permission from Shah BR, Lucchesi M: Atlas of Pediatric Emergency Medicine. McGraw-Hill, 2006. Photo contributor: Michael H. Siegel, MD)
In all cases where airway injury is suspected, endotracheal suctioning and other blind airway interventions should be avoided. Smaller, more distal injuries can be managed with a chest tube and observation. With more significant injuries, establishing an airway can be complicated, particularly when the trachea is disrupted or a peritracheal hematoma distorts the airway anatomy. When intubation is necessary, fiberoptic assistance will minimize further traumatic injury, especially in cases of incomplete tears. If a surgical airway becomes necessary, it should be placed below the level of the disruption by tracheostomy or cricothyrotomy. Inability to ventilate, once an airway has been established, requires emergency thoracotomy to repair or alleviate the disruption.
Traumatic asphyxia is an injury unique to children due to the increased compliance of the chest wall and absence of valves in the superior and inferior vena cava. Sudden, direct compression of the elastic pediatric thoracic cage against a closed glottis causes dramatic increases in intrathoracic pressure, temporary vena cava obstruction, and transmission of the pressure into the capillaries of the head and neck. This results in cyanosis, plethora, and petechiae of the head and neck, subconjunctival hemorrhages, face and neck edema, and rarely, intracranial hemorrhage. Clinical presentation varies depending on the forces applied. More severe cases may present with respiratory distress, altered mental status, and seizures. Approximately one-third of these patients will experience a loss of consciousness. Transient and permanent visual disturbances can occur due to retinal hemorrhages and edema. The presence of traumatic asphyxia serves as a marker for associated head trauma, pulmonary contusions, and intra-abdominal injuries. Treatment is supportive and manages any complications.
Traumatic Esophageal Rupture
Traumatic esophageal rupture is also extremely rare in children. It occurs with severe blunt upper abdominal trauma in which stomach contents are forcefully injected into the esophagus against a closed cricopharyngeus muscle causing a rupture of the esophageal wall into the mediastinum. Clinical signs include pain and shock out of proportion to the apparent severity of injury. Esophageal rupture should be suspected if the patient has an associated pneumothorax that drain stomach contents upon evacuation by chest tube or if there are signs of air leak equally and continuously throughout the respiratory cycle. Subcutaneous emphysema may dissect into the neck and be palpable on examination. Although rare in children, Hamman's sign (mediastinal crunch) may be appreciated as a crunching sound with heart sound auscultation. Chest radiograph often reveals pneumomediastinum (or mediastinal emphysema), which may be the only clue to the diagnosis. Fluoroscopy with water-soluble contrast or endoscopy can confirm the diagnosis. Urgent surgical repair with mediastinal drainage is required. With extensive esophageal damage, temporary esophageal diversion may be required and definitive repair delayed. If unrecognized, this condition progresses rapidly to mediastinitis, sepsis, and death despite surgical intervention.
Traumatic Diaphragmatic Hernia
Traumatic diaphragmatic hernia in children occurs with both blunt and penetrating chest and/or abdominal trauma. It is more commonly associated with forceful injuries that cause a sudden increase in intra-abdominal pressure. One example is the “lap belt” complex, when children involved in motor vehicle crashes are improperly restrained with only lap belts. The small pelvis of a child allows for the displacement of the lap belt upward onto the abdomen. The acceleration/deceleration forces applied to the abdomen result in compressive forces that may injure the organs directly or cause intra-abdominal pressure significant enough to rupture the diaphragm. The left hemidiaphragm is involved in the majority of cases. Associated injuries involving the liver, spleen, and intestines are seen frequently. With penetrating trauma, diaphragmatic laceration is possible when the injury is sustained inferior to the nipple line.
Because of the few early symptoms, there is often a delay in the diagnosis of traumatic diaphragmatic hernia, with only 50% to 60% being diagnosed in the acute phase. Respiratory symptoms result not from the hernia itself, but from herniation of abdominal contents into the chest cavity. Lung function is compromised by the physical space constraint and compression of the lung parenchyma. Clinical findings may include contusions and abrasions of the upper abdomen and lower chest wall, but herniation can occur without external signs of trauma. Breath sounds may be decreased or bowel sounds heard on the affected side. Chest radiograph findings depend on the status of the abdominal contents and are outlined in Table 25-3. A high index of suspicion is necessary to consider this diagnosis.
TABLE 25-3Chest Radiograph Findings in Traumatic Diaphragmatic Hernia ||Download (.pdf) TABLE 25-3 Chest Radiograph Findings in Traumatic Diaphragmatic Hernia
Chest radiograph with acute herniation of abdominal contents
Chest radiograph with diaphragmatic tear but delayed herniation of abdominal contents
Unexplained elevation of the hemidiaphragm
Unrelieved acute gastric dilation
Loculated subpulmonic hemopneumothorax
Presence of the nasogastric tube in the chest
Acute traumatic diaphragmatic herniation requires surgical repair. However, initial management should concentrate on adequate oxygenation, ventilation, and stabilizing other injuries. A nasogastric tube should be placed to decompress the stomach and intubation with positive-pressure ventilation performed to ensure adequate ventilation. With delayed presentations, chest radiograph may demonstrate the pathology. Some cases may require confirmation by fluoroscopy or in rare cases by laparotomy.
Rib fractures are uncommon in children because of their compliant, cartilaginous thoracic cage. When rib fractures do occur, they are often the result of a direct blow to the chest or significant anterior–posterior forces seen with crush or squeezing mechanisms. The posterior-lateral aspect of the ribs is most susceptible to fracture from all causes. In isolation, rib fractures are rarely a source of mortality. However, because of the significant forces needed, such fractures serve as important markers for potentially serious underlying injuries. Evaluate the patient carefully for associated pulmonary contusions, pneumothorax, and hemothorax. When the first rib is involved, be suspicious for clavicular fractures, head and neck injuries, central and peripheral nerve injuries, and major vascular trauma. Multiple rib fractures are often associated with multisystem organ involvement and carry a higher risk of morbidity and mortality. Lower rib fractures may be associated with abdominal injuries. Even when not associated with injuries to the abdominal organs, referred pain from rib fractures alone can confuse the diagnosis.
Without a clear history of trauma, and particularly if there are multiple fractures in various stages of healing, child abuse should be suspected. Up to 30% of abused children will have sustained rib fractures. All cases of suspected child abuse should be immediately reported to child protective services and local law enforcement agencies.
Most rib fractures are diagnosed by screening chest radiograph. However, up to 50% of isolated rib fractures may not be diagnosed on the initial chest radiograph. Isolated rib fractures are self-limited in nature and often do not require any additional workup. In cases of multiple rib fractures or an isolated first rib fracture, further radiographic evaluation with rib series, chest CT scan, or angiography may be necessary to detect underlying injuries. Despite normal neurovascular examinations on presentation, fractures of the first rib should be considered high risk for underlying occult vascular injury and prompt the provider to initiate additional diagnostic testing and treatment. Sternal fractures and costochondral separations are also not easily recognized on chest radiograph or rib series, but should be suspected if there is point tenderness, crepitus, or obvious deformity.
Simple rib fractures are well tolerated in children. Treatment involves optimizing the patient's respiratory effort with aggressive pain management and breathing therapy with incentive spirometry. In cases where pain is severe enough to cause splinting and atelectasis, intercostal nerve blocks may be necessary to facilitate the healing process. These efforts will help in the prevention of atelectasis and complicating pneumonias. Associated pneumothorax or hemothorax should be drained promptly to allow for better lung function.
Severe blunt trauma to the chest wall can cause two or more fractures to the same rib. When this occurs in more than two adjacent ribs, the structural integrity of the chest wall is compromised, causing a flail chest. This isolated segment of ribs moves paradoxically, making respirations ineffective. Children with large flail rib segments are at risk for respiratory failure from inadequate ventilation.
Signs and symptoms include varying degrees of respiratory distress and hypoxia along with the classic paradoxical chest wall motion. Tenderness, bruising, and crepitus overlying the flail segments are often present. Muscle spasm and respiratory splinting may obscure the clinical diagnosis by “stabilizing” and concealing the flail segments on physical examination.
Chest radiograph confirms the diagnosis (Fig. 25-6) and often reveals associated pulmonary contusion. Treatment is aimed at preventing hypoxia and respiratory failure, and is dependent on the extent of injury and the child's degree of respiratory compensation. Supplemental oxygen and close monitoring may be all that is required. The addition of intercostal or epidural nerve blocks for pain control is preferable to narcotic analgesia because of the potential for respiratory depression associated with narcotics. Patients with paradoxical respirations from large flail rib segments will need positive-pressure ventilation until rib operative fixation occurs.
This is the x-ray of an adolescent who sustained significant blunt chest trauma. Note the fractures of ribs 4 through 10 seen medially that are indicative of posterior rib fractures, and the more peripheral fractures seen in ribs 4 through 8. This patient presented with paradoxical movement of the chest with breathing, crepitus of subcutaneous emphysema, and a pneumothorax that required placement of the chest tube (also seen on the x-ray). (Reproduced with permission from Shah BR, Lucchesi M: Atlas of Pediatric Emergency Medicine. McGraw-Hill, 2006. Photo contributor: Binita R. Shah, MD)
Thoracic spine injuries are less frequent in children suffering thoracic trauma, but when present are most likely the result of motor vehicle crashes and falls. One study of severely injured pediatric patients with spine injury reported thoracic injury to be the most commonly associated injury (89%) followed by TBI (64%).29 Cervical and thoracic spine immobilization should be maintained until evaluation is complete and these areas are cleared of injury.
If clinical suspicion remains high despite normal radiographs, CT scan can help detect small fractures. When there is concern for spinal cord or ligamentous injury or a child has suffered immediate or progressive neurologic deficits, obtain magnetic resonance imaging (MRI) to evaluate for operative lesions such as expanding epidural hematomas causing cord compression. Remember that some patients have spinal cord injury without radiographic abnormality, which is discussed in Chapter 24.
Cardiac and great vessel injuries are uncommon in children, but when they do occur, they increase the morbidity and mortality. Myocardial injury in children can occur in isolation or in association with multiple injuries. Pericardial tamponade is the most common injury seen with penetrating mechanisms. Traumatic aortic rupture is the most common great vessel injured, but is still underreported since more than 50% of victims succumb to this injury before reaching the hospital.
Cardiac contusion is the most common unsuspected and under diagnosed injury from blunt thoracic trauma. The National Pediatric Trauma Registry estimates that up to 5% of pediatric victims of blunt chest trauma suffer cardiac contusions. One study, which looked at children with blunt thoracic trauma severe enough to produce pulmonary contusion or rib fracture, found that 43% of these patients had a significant cardiac contusion.30 Cardiac injury is most often sustained as a result of motor vehicle crashes and pedestrian injuries. Myocardial injury tends to be more severe in cases of multisystem trauma.
A combination of clinical suspicion based on mechanism of injury, clinical examination findings, and cardiac-specific evaluation help diagnose cardiac injury. Children may complain of significant tenderness in the anterior chest or poorly localized chest pain. However, up to half of patients with cardiac injury have no complaints of chest pain, and in most cases there is no external evidence of trauma and the cardiac examination is normal.30 Tachycardia is the most sensitive and important indicator of myocardial injury. However, pain and anxiety produce impressive tachycardia that can complicate the diagnostic process and may mask concern for cardiac contusion. Children with more severely injured myocardium may present with dysrhythmias, hypotension, and signs of cardiac failure. ECG abnormalities are less common in children and a normal ECG may lead to a missed diagnosis if used as a defining tool alone. In one study, 43% of patients with blunt chest trauma, with a significant cardiac contusion, did not have ECG abnormalities.30 Diagnosis was made by abnormalities in cardiac function on echocardiography and radionuclide angiography/MUGA scan, and an elevation in cardiac enzymes. Patients who present to the emergency department (ED) in a stable hemodynamic state and in normal sinus rhythm rarely develop serious cardiac sequelae. Elevation of cardiac-specific enzyme levels, specifically troponin I, is an important indicator of cardiac contusion. Cardiac-specific evaluation should focus on the assessment of function by echocardiography.
Management of cardiac contusion is mostly supportive. Children with suspected cardiac injury should be admitted for observation with cardiac monitoring and serial measurement of cardiac enzymes.
Cardiac tamponade is a life-threatening condition that occurs when fluid (blood or serous fluid) fills the pericardial space to such an extent that venous return is compromised causing normovolemic shock and death. Penetrating injuries, like stab and gunshot wounds, are the most common etiology and typically cause acute deterioration and death. Even with small lacerations of the pericardium, life-threatening hemorrhage and tamponade can occur. These injuries may rapidly cause progressive hypotension and pulseless electrical activity (PEA) unless treatment is initiated promptly.
Diagnosis of cardiac tamponade is made clinically, but confirmation is assisted with echocardiography. Clinical findings that are concerning for cardiac tamponade include the presence of a precordial wound, tachycardia, narrow pulse pressure, and pulsus paradoxus. Beck's triad with muffled or distant heart sounds, hypotension, and jugular venous distention may be present but may not be a reliable clinical indicator in the presence of hypovolemia.
Chest radiograph typically shows the classic “water bottle” cardiac silhouette. The ECG often shows tachycardia with extremely low voltage, or it may show evidence of acute myocardial infarction if a coronary artery has been lacerated.
Bedside echocardiography is diagnostic; however, treatment should not be delayed while waiting for the echocardiogram. Treatment should be based on clinical suspicion and a scenario of patient deterioration or arrest. Definitive treatment requires thoracotomy, pericardiotomy, and repair of the underlying injury. Although its role has become limited, in certain circumstances pericardiocentesis is both diagnostic and therapeutic. However, there is a high incidence of false-negative results, where a negative pericardiocentesis does not necessarily rule out a hemopericardium. With rapid bleeding into the pericardium, blood often clots making it impossible to relieve the tamponade without a thoracotomy. Pericardiocentesis should only be performed by providers trained in emergency procedures. It should be performed when the patient's condition is rapidly deteriorating and definitive thoracotomy is not readily available. Repeated aspirations may be necessary, so the needle or plastic angiocath is generally left in place until a thoracotomy can be done.
In certain circumstances, an emergency pericardial window may be necessary to relieve the tamponade and control bleeding until definitive treatment can be performed. Bleeding may be controlled by directly clamping the injured area; however, the coronary arteries are particularly sensitive to compression and pressure changes, and may be damaged easily. Repeated pericardial aspiration and aggressive blood resuscitation are reasonable alternatives until a physician with expertise in emergency thoracotomy is available.
Traumatic Rupture of the Great Vessels
Injury to the aorta and great vessels is rare in children and more often the result of blunt trauma.10 Traumatic vascular injuries include dissection, intimal flaps, occlusion, and transection. Blunt aortic injury is most commonly caused by rapid deceleration, as seen in high-speed automobile crashes and falls from great heights. Thoracic aortic injuries occur more often in unrestrained children, whereas restrained children suffer more injuries to the abdominal aorta.31,32 Rupture of the great vessels is rare in children due to the higher elastin content of their connective tissue. However, children and adults with Marfan's syndrome or similar connective tissue disorders are more susceptible to these injuries because of the intrinsic weakness of their un-crosslinked collagen.
Injury to the thoracic aorta is the most common great vessel injury from blunt trauma, and disruption at the level of the ligamentum arteriosum is the most common site accounting for an estimated 95% to 99% of all pediatric traumatic disruptions.33 Morbidity and mortality are high with injuries to the great vessels. Paraplegia is the most significant complication for survivors of such an injury.
Many children will have significant associated injuries to the chest, abdomen, and central nervous system. In one study, the most common concurrent injury was solid abdominal organ injury in 53% of patients.32 It is important to have a high index of suspicion for great vessel injuries because additional injuries to other organs can mask the diagnosis of an aortic dissection.33 It is not uncommon for there to be no external evidence of thoracic injury.
Making the diagnosis can be difficult in children. Chest radiograph findings (Table 25-4), although sometimes subtle, can increase suspicion for aortic injury. A widened mediastinum and prominent aortic knob on chest radiograph are the most common findings, but these alone do not confirm the diagnosis. Chest CT scan will help better delineate the injuries, but may miss small tears. In cases where there is ongoing blood loss, diagnosis is confirmed by angiography. Early surgical consultation, with chest CT angiography and/or arteriography, is the diagnostic modality of choice in the setting of suspected aortic rupture or dissection. Definitive treatment requires immediate surgical repair. Initial treatment should be directed toward the ABCs of trauma care while the surgical team prepares for surgery. Concurrent hemopneumothorax should be treated with a thoracostomy tube unless an ED thoracotomy is indicated.
TABLE 25-4Chest Radiograph Findings in Aortic Injury ||Download (.pdf) TABLE 25-4 Chest Radiograph Findings in Aortic Injury
Widened mediastinum with obliteration of the aortic knob
Dilation of the ascending aorta
Evidence of first and/or second rib fracture
Penetrating trauma and impaled objects cause injury to the vena cava or pulmonary vessels more often than injury to the aorta. With isolated venous or pulmonary vessel injuries, patients often survive to surgery even with severe injuries. A vascular injury should be considered with any obvious wounds to the chest associated with hypotension. Hypovolemic shock is often present initially and may respond to fluid resuscitation only to recur as the slow venous bleeding progresses.