Evaluation and Management of Pediatric Chest Trauma
Evaluation and Management of Pediatric Chest Trauma
Author: Mark D. Lopez, MD, FAAEM, FACEP, Associate Professor, Departments of Emergency Medicine and Pediatrics, Section of Pediatric Emergency Medicine, Medical College of Georgia, Augusta, GA.
Peer Reviewer: Robert W. Schafermeyer, MD, FACEP, FAAP, FIFEM, Associate Chair, Department of Emergency Medicine, Carolinas Medical Center, Charlotte, North Carolina, Clinical Professor of Pediatrics and Emergency Medicine, University of North Carolina School of Medicine, Chapel Hill, NC.
Care of the seriously injured child is tough. When I was working in a community hospital in the "pre-trauma system" era, when the injured were taken to the closest hospital, some of the most challenging patients were injured children, a few of which I still remember.
Thankfully, the seriously injured child is uncommon, and regionalized trauma care systems have identified specific hospitals as pediatric trauma centers so that these patients can receive expert care. The trade-off is that the community hospital sees less of these victims, and knowledge and skills become atrophied as experience wanes.
This article is designed to refresh and update the community emergency physician knowledge base for the assessment and management of pediatric chest trauma.
J. Stephan Stapczynski, MD, Editor
Introduction
Trauma remains the leading cause of mortality in children and adolescents.1,2 Eighteen thousand deaths are attributed to trauma each year.3 In fact, trauma kills more young Americans than all diseases combined.
The care of children with trauma can pose difficulty for the emergency physician as the variables of age, injury mechanism, and response to therapy are challenging for institutions that do not have significant pediatric trauma volume. A retrospective analysis from a rural state of 138 cases approximately 10 years ago illustrates this point. While only one death was considered preventable (< 1%) and 11 deaths (8%) were considered potentially preventable, a larger number of cases received care that was considered inappropriate with expert guidelines; 16% in the prehospital phase and 47% in the in-hospital phase.4 The inappropriate care for the pediatric population was most frequently secondary to the control and management of the airway.
As young children and adolescents develop and strive for independence, their risk-taking behavior increases.3 This becomes very evident when they begin to drive. Traffic accidents cause the vast majority of the injuries in adolescents, but sports injuries, personal violence, and suicides also contribute. Infants and young children are more prone to falls, drowning, and transport related mechanisms such as skateboards, scooters roller skates, bicycles, and others.3,5
Injuries to the chest account for only 5-12% of the admissions to trauma centers. However, they have a greater lethality. In isolation, pediatric chest trauma has a 5% mortality. This goes to 25% when these patients have concomitant head or abdominal injuries, as is most commonly seen in significant trauma.5 Thoracic injuries in children are mostly secondary to motor vehicle accident related trauma. The most common thoracic injuries in pediatric trauma are pulmonary contusion and pneumothorax. (See Table 1.) These injuries can often be managed conservatively or with the use of tube thoracostomy.6
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Pediatric Trauma Care
Pediatric trauma management does not have an robust evidence-based grounding; most of the guidelines have been adapted from the adult trauma literature. The American College of Surgeons Committee on Trauma requires that for Level 1 and 2 Trauma Center verification that a senior level surgeon (attending or chief resident) be in-house and readily available 24 hours a day to manage seriously injured patients. This requirement may be difficult for free-standing children's hospitals that aspire to be verified by the ACS-COT as Level 1 or 2 Pediatric Trauma Centers..
The implementation of resident duty hours has also impacted the ability of free-standing children's hospitals to have chief surgical residents in-house 24 hours per day. Many hospitals have instituted a tiered-trauma activation response, with the emergency physicians performing the initial assessment while the trauma surgeon is called in from home. This process has been better studied in adult trauma centers, and there is some experience from children's hospitals that with this approach, pediatric emergency physicians can handle the initial assessment and resuscitation of most pediatric trauma patients.7 This concept allows more hospitals to operate as trauma centers and provide more accessible care to the community, with the trade-off that there may be a rare case where the lack of an in-house surgeon may delay the case of a child with lethal injuries who requires immediate operative intervention.
Since many injured children are cared for in general hospitals and not specialized children's hospitals, it is important that the emergency physician have a good understanding of the treatment needs of pediatric trauma victims and, more specifically, the care of pediatric chest trauma.
Pathophysiology of Thoracic Trauma
The main consequence of injury as a result of thoracic trauma is the impairment of oxygen delivery and/or transport. This can be secondary to factors that determine pulmonary gas exchange, cardiac output, hemoglobin concentration, and oxygen-hemoglobin affinity.
Children do not have the same responses to trauma as adults do. (See Table 2.) There is an increased head-to-body ratio and skin surface area (surface-to-mass ratio), diminished cardiopulmonary response, and different circulatory responses.3 Children have a softer chest wall, allowing for less protection to the underlying parenchyma. This allows for more direct transfer of energy to the underlying lung.6 An apparently simple injury may easily damage the intra-thoracic organs.1
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The single most common injury in pediatric blunt trauma is pulmonary contusion. Hypoxemia and respiratory mechanical insufficiency are the most common causes of morbidity in the early time period. The physiologic consequences include ventilation/perfusion mismatch, decreased compliance, hypoxemia, and hypoventilation.5 Complications include pneumonia and the acute respiratory distress syndrome. Treatment involves the early diagnosis, maintenance of euvolemia, and selective mechanical ventilation to limit morbidity.8 Shear forces can also disrupt the bronchi, which leads to pneumothorax or tension pneumothorax.
Children have a diminished functional residual capacity coupled with higher oxygen consumption per unit mass. Therefore, young children are more prone to the rapid evolution of hypoxemia.5 Compensatory mechanisms that can be implemented center on ventilatory support and the arrest of hemorrhage.2 Airway management requires adequate preoxygenation, expeditious intubation, and minute ventilation adjusted to age, weight, and metabolic rate.5
Children have excellent cardiac function and typically no underlying coronary artery disease as seen in adults. They are able to compensate for greater amounts of hypovolemia. An adult may manifest hypotension after 15-20% blood volume loss, but children remain compensated with up to 40% blood loss.5 There can also be contusions to the heart from the crush injury between the sternum and vertebrae.
Another, but less common intra-thoracic injury in blunt trauma is great vessel disruption. During sudden profound deceleration, the heart swings on the aorta, tearing the great vessels. This is known as the "bell clanger" effect. The ligamentous attachment of the descending aorta to the left pulmonary artery is the most common site.2
Penetrating Thoracic Injuries
The major physiologic consequence of penetrating trauma is hemorrhage. Instead of respiratory distress, symptoms of penetrating chest trauma may only be that of circulatory shock, with restlessness, agitation, tachycardia, sweating, pallor, and peripheral vasospasm, with reduced capillary circulation. No outward bleeding need be noted. Each hemithorax can hold up to half of a patient's total blood volume.2
The most common injury from penetrating chest trauma is a pneumothorax, with or without a hemothorax. The majority of these patients can be treated with tube thoracostomy. (See Table 3.) For patients without apparent injury on initial chest radiograph, expert guidelines recommend a period of observation to detect if a delayed pneumo-hemothorax develops.9 The period of observation required is not well defined. For example, one small study found that children with penetrating chest trauma can be safely discharged if the vital signs are normal and the chest radiograph does not show any injury after a 4-hour period of observation.10 Some trauma surgeons are more cautious and require a longer period of post-injury observation to detect a delayed pneumothorax or hemothorax.
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Operative intervention for penetrating chest trauma is required for major intrathoracic vascular or airway injury. Major vascular injury is suggested by either massive hemothorax (15 mL/kg initially out after chest tube insertion) or ongoing bleeding (3 to 4 mL/kg per hour).5 Airway injury is suggested by persistent pneumothorax after chest tube insertion and/or continued bubbling in the water-trap drain.
Antibiotic prophylaxis in the treatment of chest trauma is debatable unless there is esophageal rupture.9 Mandel and Oparah reported that wounds from low-velocity missiles are considered clean. Those from high-velocity missiles are considered contaminated because they bring a large amount of foreign material into the wound sites.11
Gun Shot Wounds
There has been a significant increase in the number of penetrating thoracic firearm injuries to children in the past 15 years.12 Between 1968 and 1991 there was a 60% increase. The greatest incidence of gun shot wounds occurs in 15- to 19-year-olds, especially among black teenagers. Ten percent to 15% of these are intrathoracic injuries.13
Thoracic firearm injuries most often damage the lungs, with pulmonary contusion with or without a pneumothorax or hemothorax being the most frequent specific injury.12 In most cases, tube thoracostomy is the only surgical procedure needed. Surgical thoracotomy is most often required for patients with severe injuries and penetrating thoracic wounds from shotguns or explosions.12
High-velocity gun shot wounds generally cause more extensive damage at the exit of the bullet. They cause severe tissue damage beyond the initial tract of penetration. They produce more intense cavitation, laceration, and contusion of the chest wall, lungs, and surrounding tissue. Low-velocity gunshot wounds have limited minimal chest trauma to the bullet entry and exit sites. They exhibit minimal injuries, lacerations, and contusions to the lungs. Shot-gun wounds exhibit multiple pellet incursions that are spread out over a large area. They can cause widespread damage to the chest wall and lead to lung contusions. They tend to cause multi-organ injuries.
The destruction of tissue is directionally proportional to the velocity and energy of the missile. Doubling the velocity quadruples the energy. Therefore, low-velocity gun shot wounds do not transfer a lot of energy to the surrounding tissues, whereas high-velocity gun shot wounds transfer a large amount of energy to the surrounding tissue.12
Thoracotomy is infrequently required in children. Most penetrating wounds can be managed with tube thoracostomy and supportive measures where no gross pulmonary lacerations or airway injuries have occurred.12
Ballistics
To better understand gun shot wounds, the practitioner needs to understand some of the mechanics of ballistics. With this information, the physician can understand and look for injuries in the chest.
Common elongated bullets are spin-stabilized to maintain their flight in air. They have aft centers of gravity and would yaw (deviation from its line of flight) without the spinning force in the muzzle of the firearm.14
Bullets that enter liquid or solid media (body tissue) are unable to maintain their stability and typically yaw as the pressure on the nose and the center become much greater than in the air. The penetration therefore is decreased, and there is an increase in both the temporary and the permanent cavity formed by the bullet track. Furthermore, the track may not remain linear.
BBs are spherical objects that maintain their shape during penetration and therefore do not deform. They obey a linear relationship to their entry in low velocity. They have less of a tendency to yaw and deviate from a straight path in tissue.
Ricochet involves the transfer of energy to another direction. The steeper the incident angle (angle of penetration to the object it strikes), the more energy is transferred to the bullet and the more likely the bullet is to fragment or penetrate the object (i.e., bone) it struck. A model to ricocheting is light striking a mirror. The steepest angle is to point the light directly at the mirror and back to the source.
In real injuries, the bullet will lose some of its velocity from the impact. It will then depart at an angle different from the incident angle. There will likely be some deformation of the bullet and some breakup. The impacted surface will likewise be deformed. The impacted matter will be embedded into the projectile, and traces of the bullet will be left at the site of impact.
Blunt Thoracic Trauma
Blunt chest trauma is more common than penetrating trauma in children. The most common cause is motor vehicle crashes, followed by a pedestrian stuck by a vehicle, falls, stab wounds, gun shot wounds, and fights. Other causes include blast injuries, animal injuries, back-over injuries, child abuse, and, rarely, commotio cordis.
Although 15% of children with blunt thoracic trauma are fatally injured, this is less often the direct result of chest injury (15%). It is more often due to a concomitant injury such as head injury.
In a retrospective review of pediatric trauma, it was found that the highest mortality in children was due to chest trauma (19%) with the most lethal combination being head plus torso trauma (25%). Chest trauma results in up to a 17-fold increase in mortality over children without thoracic trauma.3
Another mechanism for blunt chest trauma is driveway back-over injuries. With the increasing popularity of SUVs and vans, this type of injury has become more prevalent. In a Consumer Reports article, the blind spot of several popular vehicles was noted to be from 2 feet to 34 feet for average size drivers (5 ft. 8 in.), and from 10 feet to 51 feet for short drivers (5 ft. 1 in.).15 According to KidsandCars.org as of Sept. 8, 2007, there had been 170 fatalities due to this injury.16 This injury type tends to occur in the warmer months and after school (15:00-20:00). In a study by Fenton et al,. researchers found the most commonly involved age group was younger than 5 years old, and that chest trauma had the highest mortality rate (11%), especially in accidents involving SUVs.17
Blast Injuries
In a retrospective study of the Israel National Trauma Registry between 2000 and 2002 of acts against civilians, explosions were the most common cause of injury (71%) with shootings next (21.5%), and other mechanisms such as stoning and stabbing last (6.3%). During this time there were only 158 acts against civilians, but 2462 injuries due to motor vehicles. The highest injury specific mortality rate in explosions was due to truncal injuries with a mortality of 10.5%. Injuries included blast lung due to pulmonary contusions, hemopneumothorax, emphysema, and alveolar-venous fistulas.18
Injuries in Chest Trauma
Pulmonary Injuries. Pulmonary contusion is the most frequent thoracic injury in pediatric chest trauma. The use of passive and active restraints has decreased the prevalence to about 10% of all pediatric trauma admissions.
Secondary complications from pulmonary contusion are still very common. Approximately 20% of children with pulmonary contusions progress to pneumonia and some to respiratory failure. Half of those who develop respiratory insufficiency will do so in the first few hours. Acute respiratory distress syndrome occurs in only 5-15% of the cases. Death from these complications in children is rare.5
Pneumothorax occurs in isolation or in combination with other injuries. Among all children who sustain chest trauma, one-third will develop a pneumothorax. Initially it is often asymptomatic. Early chest radiography should be standard in the setting of chest trauma. Follow up chest x-rays in the following days or CT scans may eventually reveal pneumothoaces.5
Tension pneumothorax develops in up to 20% of children after a simple pneumothorax. This is the progressive accumulation of air within the pleural cavity. Auscultation of the chest can be very misleading. If tension pneumothorax is suspected, the physician should act immediately to decompress the hemithorax. This leads to the collapse of the ipsilateral lung and the compression of the contralateral lung. The mediastinal structures are shifted to the contralateral side, and compression of the vena cava occurs. Venous return to the heart is reduced, and the patient may appear tachycardic, peripherally vasoconstricted, and in hypotensive shock.19 Infants have a very mobile mediastinum, and this will occur more rapidly than in the older child whose mediastinum has become fixed.5 Needle or tube thoracostomy is needed emergently to relieve the pressure within the chest.
Injuries to the tracheobronchial tree are rare. Disruption may occur in blunt trauma with high acceleration or deceleration forces. Most of these injuries are in the distal trachea or proximal bronchi. Typically the patients present with mediastinal air, although some may present with tension pneumothorax. (See Figures 1 and 2.)
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Other signs include air leaks from chest tubes, mediastinal air, and cervical subcutaneous emphysema without the presence of a pneumothorax. Approximately 33% of these injuries are fatal. Thoracostomy and fiberoptic intubation are essential interventions in these cases. Ultimately, surgical repair is indicated. Late treatment can result in airway stenoses, atelectasis, and pneumonia.5
Hemothorax presents secondary to the rupture of any of the intrathoracic vessels such as in rib fractures that lacerate intercostal arteries or veins. Rarely the vena cava or aorta may be disrupted. Up to 40% or 50% of the child's blood volume can be held in each hemithorax. The treatment consists of drainage by thoracostomy. Delay can lead to a fibrous scar that may continue to chronic atelectasis, ventilation/perfusion mismatch, and pneumonia.5
Blunt cardiac injuries are rare in children. Most occur in children younger than 10 years of age. They typically present with dysrhythmias, unexplained hypotension, or elevation of cardiac enzymes. Management is supportive. Inotropics may be used but will also increase myocardial oxygen consumption and irritability.5
Fractures. As noted above, children have more compliant chests than adults do, and their chests absorb and transfer the forces to the underlying structures. This explains the relatively fewer rib fractures sustained in pediatric chest trauma when compared to adult chest trauma.
The most commonly reported fractures in chest trauma in children are rib fractures. In isolation, broken ribs are a rare source of mortality or morbidity, but they are indicators of significant energy transfer.5 A retrospective series of pediatric trauma patients found that 14% of children with rib fractures in pediatric trauma died. Those who had multiple rib fractures had a higher mortality rate.20 Therefore, in the context of multiple rib fractures, careful survey of the child's bone, neurologic, and vascular anatomy may reveal multiple, significant injuries.5
Flail rib segments, or multiple contiguous ribs with more than two points of fracture, are rare in children. However, they do lead to significant respiratory dysfunction. Positive pressure ventilation and pain control are typically sufficient treatment.5
Fractures of the spine may occur in the settings of axial loading as in football, diving, or falls. Also, in translational deceleration that leads to spinal cord or ligamentous injury from hyperflexion or hyperextension as seen in a seated passenger of a motor vehicle crash. In adults, fractures of the thoracic spine have been associated with rupture of the thoracic aorta. This association has not been reported to be consistent in pediatric chest trauma. The above cited retrospective study had thoracic fractures in 10% of their population and none died. Children's bones are not completely ossified, thus allowing the ligamentous attachments to be more flexible. Children may experience more injuries to surrounding structures without plain film abnormalities. Magnetic resonance imaging (MRI) is the most useful in the context of spinal cord injury without radiologic abnormality. This looks for spinal cord contusion, hemorrhage, transection, or central cord syndrome.5
Clavicular and scapular fractures are less common fractures in significant pediatric chest trauma. They are less frequently associated with mortality as compared to rib fractures.20 They tend to occur in motor vehicle crashes and daily falling injuries most commonly.21
Commotio Cordis. Commotio cordis or concussion of the heart is ventricular fibrillation that results from an impact-induced energy that was transmitted via the chest wall to the myocardium during its vulnerable repolarization period.22 Although ventricular fibrillation is the most commonly documented cardiac rhythm abnormality, other dysrhythmias such as complete atrioventricular block, idioventricular rhythm, and marked ST-segment elevation in the precordial leads can also occur.23 A common scenario is a sporting event where a child is hit in the chest with a baseball. Another scenario is child abuse, and this needs to remain in the differential after resuscitation. Most patients tend to be boys and most patients do not survive. The prognosis depends on the availability of cardiac defibrillators. Early cardiopulmonary resuscitation and defibrillation may improve survival. The child will then need to have cardiac clearance to return to sports since transient cardiac conduction abnormalities and arrhythmias have been found in the survivors.24
Treatment of Pediatric Chest Trauma
General. As mentioned above, most chest trauma patients can be treated conservatively with respiratory management and tube thoracostomy. All traumas should begin with the basic assessment of trauma that all emergency physicians are familiar with: airway, breathing, and circulation (ABC). (See Table 4.) If the patient presents with respiratory distress or failure, an airway must be secured and appropriate ventilation management instituted. Oximetry and end-tidal capnography are useful monitoring technologies in this regard. Once the airway and breathing are addressed the circulatory status should be attended to. Pericardial tamponade, tension pneumothorax, hemothorax, and blood loss need to evaluated and treated. An early chest radiograph is helpful in identifying chest injuries. Tube thoracostomy is the most commonly needed treatment and will treat the most common injuries of pneumo- and hemothorax.
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Airway Management. The airway and the maintenance of good ventilation are the first priorities and the most important steps in the management of pediatric chest trauma. Airway obstruction can occur from blood, vomit, or other particulate matter and needs to be addressed immediately. The practitioner should be familiar with rapid sequence intubation and the mechanics of intubation.
Major chest trauma will likely have, at a minimum, pulmonary contusions present and likely rib fractures, so it would be wise to intubate early to maintain good ventilation. Specifically, patients already presenting to the trauma room with respiratory distress, mechanical obstruction, and external compression of the pulmonary structures from air or blood within the pleural cavity should be mechanically ventilated early. Once an airway is secured, the sources of obstruction and compression can be further delineated. An orogastric or nasogastric tube should be placed to decompress the stomach and reduce the aspiration risk of blood or vomit.
End tidal carbon dioxide (PetCO2) concentrations monitoring has been shown to be a predictor of survival in blunt trauma.25 PetCO2 is proportional to the cardiac output in patients ventilated at a fixed minute volume and thus predicts the pathophysiologic state. It will be depressed by any condition that decreases pulmonary blood flow. These include hypovolemia, cardiac tamponade, tension pneumothorax, or severe head injury.
In a study by Deakin, et al., researchers found that the initial prehospital use of PetCO2 monitoring could predict the overall survival rate of their major trauma victims with PetCO2 < 3.25 kPa (< 24.4 mmHg).25 They recommended initially maintaining a low normal PetCO2 until further blood gas evaluation could be done in the hospital.
If a short transport time is expected, then pre-hospital intubation may not be necessary. Stockinger and McSwain in a 2004 study found no survival advantage of prehospital intubation over bag valve mask ventilation.26 They also found an increase in the overall scene time, which could potentially impact the golden hour interventions still needed.
Circulatory Management. The next critical need in the resuscitation of a pediatric chest trauma victim is the management of the patient's circulatory system. Bleeding sources should be identified and controlled quickly. As mentioned below, a chest tube can be placed and the amount of bleeding in the chest can be properly assessed.
Large bore IVs are preferred, but a 20- or 22-gauge will suffice. In a child where vascular access is not quickly obtained, consider interosseous access or central line placement. In any child with significant trauma, crystalloids should be started right away and, if the patient shows any signs suggestive of shock, a 20 mL per kg bolus should be administered. The clinician should evaluate the patient's response to the bolus. Signs of shock in the young child include significant tachycardia, tachypnea, and any alteration in mental status, decreased urine output, and decreased peripheral perfusion. The blood pressure will not begin to fall until the later more advanced stages of shock. Therefore early signs of tachycardia should be addressed with aggressive fluid management. When the child has a large amount of bleeding from the chest injury, blood likely will be needed.
Also, if the initial hemoglobin is seven or less, the child needs additional oxygen carrying capacity, and he or she should receive 10 mL per kg of packed red cells, since the hemoglobin level will be reduced even further as crystalloid is given to the child.
Autotransfusion is another management medium that has been found to be safe and effective in pediatric chest trauma. Children have an estimated blood volume of 80 mL per kg in children and 100 mL per kg in infants. If a chest tube loses 15-30% of the blood volume, then autotransfusion would be justified. If there is continued bleeding from the chest or other sites, then autotransfusion of whatever blood is evacuated from the chest will maximize the volume of packed red blood cells for fluid resuscitation. Complications include abnormal platelet aggregation and red blood cell hemolysis during the transfusion. The risk of bacteremia from isolated hemothorax is low.26
Other Management. Once the life-threatening injuries have been addressed, a stable patient can continue the evaluation by computed tomography and further x-rays. Most chest traumas are not isolated, so other injuries need to be addressed as well. Management of rib fractures centers on supportive measures. The prevention of atelectasis and pneumonia are best achieved with judicious use of pain medication and incentive spirometry in a child old enough to participate.
Finally, a decision to continue to surgery needs to be made in conjunction with the pediatric trauma surgeons. Indications would include tracheal/bronchial rupture, lacerations of the lung parenchyma, mammary artery, or intercostal artery, esophageal disruption, diaphragmatic hernia, pericardial tamponade, or great vessel laceration.19
Emergency Thoracotomy
The use of emergency thoracotomy as component in the resuscitation of patients with penetrating chest injuries was initially introduced in 1966 be Beall, et al.27 Since that time, the indications for emergency thoracotomy were expanded to include blunt trauma. Blunt trauma patients did not prove to benefit from the procedure, which has been mostly abandoned in those presentations.
The majority of children requiring an emergency thoracotomy are due to penetrating trauma. The improvements in transportation of the injured to the hospital has resulted in the treatment of patients that otherwise would not have survived.2 Little experience and literature aside from anecdotal reports are available in this area. The limited experience indicates that children and adults are similar in their survival rates. With the understanding that utilization of emergency thoracotomy varies, overall survival after emergency thoracotomy is around 11-12% for victims of penetrating trauma and 1-2% for victims of blunt trauma.2 This supports the adult selective thoracotomy concept that is based on the mechanism of injury and physiologic status at presentation in the ED. These include cardiorespiratory arrest following an isolated penetrating thoracic injury with signs of life prior to arrival in the ED, post-traumatic persistent hypotension due to intrathoracic hemorrhage that is unresponsive to fluid resuscitation, and persistent severe hypotension with evidence of systemic air embolus or pericardial tamponade.2
Ultrasound in Chest Trauma
Ultrasonography is currently used in the vast majority of trauma centers in the United States for the recognition of abdominal trauma. Ultrasonography for trauma is an inexpensive, portable, and easily repeated test. In blunt trauma, ultrasonography can identify hemoperitoneum with accuracy comparable to DPL and CT scan.28
Studies have found variable results on the utility of ultrasound for penetrating thoracic injuries. Soffer, et al., in 2004 reported in a study that 177 victims of penetrating torso injury evaluated with ultrasonography with an overall accuracy of 85%, a sensitivity of 48%, and a specificity of 98%.28 The researchers determined that ultrasonography lacked the sensitivity to be used alone in the operative determination after gun shot and stab wounds. Conversely, Tayal, et al., reported the same year on a study of 32 victims of penetrating anterior chest trauma that ultrasound was 100% sensitive (8 of 8 patients) for the detection of pericardial effusion and the detection of pericardial effusion correlated with the need for thoracotomy in 7 patients.29
In another study evaluating the use of ultrasound in cardiac stab wounds, researchers noted that mortality could be reduced with efficient fluid resuscitation and rapid confirmation of the diagnosis with cardiac ultrasound in stable patients with precordial wounds.30
The use of ultrasound in chest trauma seems to be useful in stable patients with suspected cardiac wounds where that knowledge would be useful early. The use in general to evaluate for the need for surgery is not as clear.
Indications for a CT of the Chest
The early chest x-ray is the standard initial radiologic examination of chest trauma. The conventional chest x-ray underestimates or overlooks the mediastinal, pulmonary parenchymal, and pleural traumatic lesion when compared to CT. Chest x-rays also have a poor ability to determine the degree of lung collapse or pneumothorax size.31 For these reasons, CT evaluation is common in chest trauma.
There have been many concerns raised on the lifetime accumulative dose of radiation from the use and over-use of CT scans. In patients with chest trauma, the indications for a CT of the chest include concomitant head trauma and a Glasgow Coma Scale of less than 8, victims of high speed motor vehicle crashes, and suspicions for vascular injuries.
A patient with a concomitant head injury and chest trauma with a low GCS will require intubation. A plain supine chest x-ray that is standard in the initial evaluation of the trauma patient is not very sensitive in evaluating occult pneumothoraces. In a 1995 study, only 40% were detected by conventional chest x-ray. The critically ill patient may require an alteration in treatment if a pneumothorax is present as the patient will be placed on a ventilator with positive pressure and have a greater likelihood of developing a tension pneumothorax.
Patients involved in high-speed vehicle crashes are prone to mediastinal and diaphragmatic injuries. These may be overlooked in the conventional chest x-ray and would manifest themselves only when they become severe enough to be clinically evident.
Another indication for a CT scan of the chest would be findings on a plain film that suggest aortic injury. These include a markedly widened mediastinum, a depressed bronchus, or a pleural cap in a child with significant chest trauma. Screening with CT scan may decrease the need for aortography by 56%.31
In the study by Karaaslan et al., only pulmonary contusions showed no difference in their treatment whether assessed by CT or chest x-ray. Since this is the most common injury in children's chest trauma, most mild chest traumas would not require CT evaluation. A CT would be indicated in the presence of hypotension, unexplained blood loss, or a Glasgow Coma Scale of less than 8 or a chest x-ray suggestive of vascular injury.
Early Transport to a Higher Level of Care
The more difficult subject of when to transfer a pediatric chest trauma patient is not well defined in the literature. The referring facility needs to evaluate and stabilize the patient to the best of their ability. However, many hospitals are small and are not well practiced in treating pediatric trauma since their volumes are small. This can lead to some preventable errors.4
The Emergency Medical and Active Labor Act requires the referring facility to stabilize the patient prior to transport. This, however, is not fully defined. A smaller hospital may not have a CT scan or a radiologist available to read it. Therefore, if the patient needed a CT for further evaluation, then that transfer would be appropriate. Also, the child with multiple injuries that would require a specialized service would be another good indication for transfer. If the hospital has no method to admit pediatric trauma patients, or if they don't have individual physicians with expertise in the management of pediatric trauma or surgeons comfortable in the care of pediatric patients, then a higher level of care is indicated.
Specific criteria for transfer to a pediatric trauma center involve the need for specialized care. As noted above, pediatric chest trauma often presents with other injuries, especially head trauma. If the Glasgow Coma Scale is less than 8, then the patient would certainly be intubated and a PICU would be needed. For patients requiring pediatric surgical care, PICU care, or pediatric subspecialists, a transfer to the appropriate facility is warranted. The transferring physician needs to recognize his or her hospital's limitations and stabilize the patient so as to safely allow the transport.
Future Treatments and Modalities
Cardiac Troponin I. A recent development in the specificity and sensitivity to cardiac injury in the adult population has been due to the cardiac troponin I (cTnI) test. cTnI in the blood is highly specific for cardiac injury. It is a sensitive and specific marker of myocardial injury in adults with ischemic heart disease. It is found only in the myocardial cell and is a potent inhibitor of the process of actin-myosin cross-bridge formation. Fetal hearts have two types, the adult cardiac isoform and an isoform similar to that found in adult slow-twitch muscle.32
In a study of ambulatory children, some with known congenital heart disorders and patients in an intensive care unit with and without cardiac injury, cTnI was shown to be less than 2.0 ng/mL in the absence of discernible myocardial damage. Those with cTnI of greater than 8 all had serious cardiac injury and died.32 The study suggested that cTnI may have a value as a diagnostic tool for cardiac contusion.
This would be important in massive trauma where it can be difficult to distinguish hemodynamic instability resulting from depressed cardiac function from contusion or from concomitant injury. This knowledge may alter immediate management decisions. However, normal levels need to be decided upon and further research is needed.
Conclusion
Pediatric chest trauma is a difficult and understudied injury. The current treatments of airway management and ventilatory support along with tube thoracostomy seem to be the most common and useful for the patient. With better scanning techniques including CT and ultrasound as well as newer lab determinations such as cTnI, the future may not require prolonged observations for infrequent complications. The above modalities could reduce the overall hospitalization stay, pain to the patient, and cost to society in medical care post pediatric chest trauma.
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This article is designed to refresh and update the community emergency physician knowledge base for the assessment and management of pediatric chest trauma.Subscribe Now for Access
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