e8 Key words traumatic brain injury, head trauma, intracranial pressure, cerebral edema, guidelines, abusive head trauma, ther apy, algorithm, herniation, neurologic outcome Abstract Severe traumatic[.]
e8 Abstract: Severe traumatic brain injury in infants and children is an important public health problem This chapter updates information on the epidemiology and pathophysiology of severe pediatric traumatic brain injury, taking advantage of the new information in the third edition of the guidelines for management of severe pediatric traumatic brain injury to provide a state-of-theart overview with guidelines and a consensus-based approach to treatment Finally, direction and recommendations for future research are presented Key words: traumatic brain injury, head trauma, intracranial pressure, cerebral edema, guidelines, abusive head trauma, therapy, algorithm, herniation, neurologic outcome 119 Pediatric Thoracic Trauma TAMARA N FITZGERALD AND CHRISTOPHER R REED PEARLS • • • • Because of increased bone elasticity, rib fractures are uncommon in children and indicate significant traumatic energy delivery, raising concern for injuries of underlying viscera or nonaccidental trauma Children can maintain normotension with up to a 40% blood loss, thus profound hypovolemia may not manifest with early derangements in vital signs Owing to their high body-surface-to-volume ratio, pediatric patients are vulnerable to hypothermia, which worsens coagulopathy and outcomes from trauma Chest radiography is a sufficient screening tool for thoracic injury unless there is significant symptomatology to justify computed tomography Epidemiology and Prevention Trauma is a leading cause of morbidity and mortality in children worldwide1 and is the leading cause of death for children in the United States Thoracic injuries account for 4% to 13% of pediatric trauma admissions.2 Pediatric mortality from thoracic trauma is 15% to 25%, second only to brain injury mortality.3 Although the majority of published studies on traumatic injury have considered only adults, efforts to better characterize patterns of trauma in children have resulted in the creation of several national databases These databases are the foundation for the majority of epidemiologic studies on pediatric trauma and include the National Pediatric Trauma Registry (established 1994), the National Trauma Data Bank, and the American College of Surgeons Trauma Quality Improvement Program (TQIP) Thoracic trauma can be divided into blunt and penetrating mechanisms of injury Blunt injuries account for the majority of pediatric chest trauma (85%) and include injuries incurred from motor vehicle collisions (MVCs), pedestrian accidents, falls, and nonaccidental trauma.4 Penetrating injuries, such as gunshot and stab wounds, are uncommon in the pediatric population, with most occurring in adolescents While recent school shootings have sparked increased public attention to this issue, school violence and violence among juveniles overall are decreasing nationally, increasing the rarity of these injuries and associated institutional experiences.5 • • There is no high-quality evidence to guide the diagnostic approach to pediatric blunt cardiac injury, in whom troponinemia is nonspecific Electrocardiogram, telemetry, and echocardiography should be used selectively based on clinical judgment Identification of a diaphragmatic injury is challenging even with cross-sectional imaging Laparoscopy may be required for diagnosis if suspicion remains high despite negative computed tomography results Thoracic trauma may result in a diverse and potentially deadly pattern of injuries Although mortality is only 5% overall for isolated thoracic injuries, the rate increases up to 20% for thoracoabdominal injuries and 40% for multisystem injury.6,7 The most prevalent causes of injury vary by age group and have been described in detail in the United States using the National Trauma Data Bank Infants and toddlers are often victims of falls, MVCs, and nonaccidental trauma School-aged children to years old remain at risk for falls and MVCs and are also frequently injured as pedestrians struck by motor vehicles Older children and teenagers (10–17 years old) are most frequently involved in MVCs but also are increasingly victims of accidental and nonaccidental penetrating trauma.8,9 Obesity does not impact the severity of injury, mortality rate, or procedural outcomes in children However, obese children are more likely to have rib and pelvic injuries.10 Anatomic and Physiologic Considerations The anatomy and physiology of the chest wall and thoracic viscera among children vary considerably compared with adults The pediatric chest wall is more compliant owing to increased cartilage content with incomplete rib ossification.11 Rib angulation and morphology also change with normal development and are associated with increased fragility with aging and senescence.12,13 Therefore, rib fractures are uncommon in children and indicate significant 1401 1402 S E C T I O N X I I Pediatric Critical Care: Environmental Injury and Trauma traumatic energy when present The relative rarity of isolated rib fractures among children underscores the importance of considering additional intrathoracic injuries even in the absence of fractures.14 Because less kinetic energy is absorbed by the ribs, more energy is transferred to the internal organs Pulmonary contusions are commonly present without rib fractures, with prevalence as high as 70% among children with known thoracic trauma In accordance with this theme of increased tissue compliance, the pediatric mediastinum and its contents are highly flexible and mobile.15 Therefore, patients can develop compressive physiology from tension pneumothorax or hemothorax at relatively low pleural pressures compared with adults Decreased venous return may lead to shock and rapid death In the context of the rarity of this condition as well as the decreased reliability of physical examination, physicians who treat injured or critically ill children must maintain a high index of suspicion in evaluation of any patient with thoracic injuries or who are mechanically ventilated and then develop sudden respiratory decompensation The smaller chest transmits breath sounds more readily Even in cases of a large pneumothorax or effusion, breath sounds may seem equal Pediatric patients are more vulnerable to developing hypoxia as their basal metabolic rate is higher, leading to greater oxygen consumption rate Children also have a smaller functional residual capacity, which manifests as a rapid decline in oxygen saturation during endotracheal intubation even when the patient has been preoxygenated by face mask The pediatric trachea is more compressible and narrow; therefore, children are more susceptible to profound respiratory distress with mucous plugging or aspiration of a small foreign body Children notoriously maintain normotension despite considerable blood losses Pediatric patients may lose 30% to 40% of their intravascular volume before manifesting derangements in blood pressure, which can lead to diagnostic delays and additional morbidity.16 Even the relatively smaller thoracic volume among young children is sufficient to contain blood to effect hemorrhagic shock in these patients Thus, the thoracic cavity should always be considered a potential source of unrecognized hemorrhage in differentiating causes of posttraumatic shock.17 Cardiac contractility is fixed in early life; therefore, heart rate must increase to maintain cardiac output in the face of diminished circulating volume This tachycardia may be the first and only sign of hypovolemia prior to rapid decompensation after injury However, heart rate is variable among children under normal physiologic conditions and is typically elevated among frightened children.18,19 Children have a relatively high body-surface-to-volume ratio, allowing for a high rate of radiant cooling Therefore, pediatric patients can become hypothermic quickly, either outdoors or in the trauma bay Hypothermia is common and deadly among severely injured patients Early interventions to correct or prevent hypothermia are critical to prevent the lethal triad of hypothermia, acidosis, and coagulopathy.20,21 Protocolized maintenance of normothermia should be considered in any patient with thoracic injuries requiring admission to an intensive care unit (ICU) Initial Resuscitation and Diagnosis Initial care of patients should follow the principles of Pediatric Advanced Life Support (PALS).22 First and foremost, the airway should be secured Inability to maintain an airway or a Glasgow Coma Score of or less should prompt orotracheal intubation Patients with suspected cervical spine injuries or unknown cervical spine status should have manual in-line cervical stabilization maintained during intubation and a cervical collar placed promptly after intubation If an adequate airway cannot be established with orotracheal intubation or is insufficient owing to maxillofacial or neck trauma, then a surgical airway should be established Once an airway has been established, end-tidal carbon dioxide (CO2) and breathing should be assessed The chest should be observed for symmetric rise and fall The right and left chests should be auscultated to ascertain adequate airflow and the position of the endotracheal tube confirmed with a chest radiograph Arterial oxygen saturation or pulse oximetry may be used to assess oxygenation Arterial CO2 measurement or capnography may be used to assess ventilation Life-threatening conditions affecting airway, breathing, and circulation—such as airway compromise, tension pneumothorax, hemothorax, and cardiac tamponade—should be identified and addressed immediately with appropriate treatment A child who loses vital signs in the trauma bay may require an emergent thoracotomy Circulation should be assessed by pulse, heart rate, and capillary refill In a warm, well child, the capillary refill should be to seconds The presence and character of central pulsations (i.e., carotid or femoral) should be assessed and described Blood pressure must be assessed with an appropriately sized cuff in order to yield accurate measurements Adequate intravenous access should be simultaneously established with large-bore peripheral intravenous (IV) catheters If peripheral access cannot be established in a severely injured patient, then intraosseous or central venous catheter (CVC) placement should be performed without delay More volume can be given over a shorter period of time through a peripheral IV line than through a CVC owing to the increased resistance over the length of the central line Intraosseous flow rates approach those of peripheral IV lines in adults and are generally preferred for rapid volume replacement compared with CVCs.23 An initial intravascular or intraosseous isotonic crystalloid bolus of 20 mL/kg should be given If the patient’s vital signs not improve, a second bolus should be given, followed by transfusion of blood products to approximate whole blood in a 1:1:1 packed red blood cell-plasma-platelet ratio.24 Once the airway, breathing, and circulation have been addressed, the child should undergo a thorough physical examination to evaluate for injuries The thoracic examination should include inspection of the patterns of bruises and abrasions that may raise concern for internal injuries The chest should be palpated to look for rib tenderness, fractures, or subcutaneous emphysema Careful examination of the back—including inspection and palpation of the thoracic spine—may raise concern for trauma to the osseous, ligamentous, or cord structures Such patients should remain flat and be “log rolled” to allow examination prior to full characterization with advanced imaging A chest radiograph is the initial screening tool for blunt thoracic trauma.25 Computed tomography (CT) can be an important adjunct in the diagnosis of blunt or penetrating trauma CT is the gold standard for detection and characterization of soft-tissue injuries of the lungs, pleura, heart, mediastinum, and its contents However, in the pediatric patient, exposure to unnecessary radiation is a significant concern.26 Although dose-reduction technologies continue to improve constantly and chest CT exposes patients to less radiation than abdominal or head examinations, thoracic CT scans contain the radiation dose of about 150 chest radiographs.27 Therefore, the routine use of CT scanning is not justified unless there is adequate clinical concern.28 Most clinically CHAPTER 119 Pediatric Thoracic Trauma 1403 useful information found on CT scans ordered for chest trauma can ultimately be correlated with findings on clinical examination and chest radiograph Therefore, chest CT should be used selectively (i.e., for the evaluation of an abnormal mediastinal silhouette on chest radiograph) given the relatively low specificity of the finding and potentially deadly implications for missed injuries to the region.29 Exposure to radiation can be limited by lowering the radiation dose, avoiding redundant studies, limiting studies based on a risk/benefit profile, and using alternative technology, such as magnetic resonance imaging and ultrasonography.30 The role of ultrasound in the pediatric trauma bay is controversial, as ultrasound appears to be less useful than in adult trauma patients.31 The reason for this lack of efficacy among children is unclear and has not yet specifically been the subject of study, although it has commanded considerable conjecture.32 The focused assessment with sonography for trauma (FAST) examination primarily assesses for abdominal injury, although the pericardium is also routinely evaluated for pathologic fluid that may herald tamponade Additionally, bilateral anterior thoracic ultrasonography may be added to the traditional four views to evaluate for pneumothorax or hemothorax (the so-called extended FAST, or eFAST).33 In one study, the sensitivity of FAST for detecting injuries requiring operation or blood transfusion was only 87% The sensitivity and specificity for detecting pathologic free fluid were 50% and 85%, respectively.34 The sensitivity of FAST is not sufficient to forego other imaging tests when there is clinical suspicion to warrant investigation; FAST has the greatest sensitivity and specificity in adults when used in the context of hemorrhagic shock after blunt abdominal or transthoracic penetrating injuries.34,35 Chest Wall Injury The elasticity of the ribs in small children protects against fractures, even in cases of severe injury Therefore, rib fractures should be considered a marker of significant traumatic energy and should prompt further evaluation of the underlying thoracic and abdominal viscera Isolated rib fractures without associated injuries are found in a minority of children Rib fractures in children are associated with higher rates of brain injury, hemothorax/pneumothorax, and liver injury.36 Higher rib fractures are not associated with great vessel injury in children; in isolation, without further concern, on chest radiograph they not warrant aortography.37,38 Lower fractures are associated with liver, spleen, and diaphragm injury Most children ages years and younger with rib fractures have been abused; abused children tend to have more rib fractures than accidently injured children Therefore, any young child who pre sents with rib fractures should raise a concern for a nonaccidental traumatic mechanism However, accidently injured children are more likely to have internal thoracic injuries than abused children (56% vs 13%) This is likely due to the difference in mechanism of injury Abuse is usually performed over a longer duration of time from manual chest squeezing or a crush mechanism Accidental trauma tends to be a single high-energy event of short duration.39 In most cases, rib fractures are treated nonoperatively However, admission may be required for pain control if multiple fractures are present The goal should be to encourage pulmonary hygiene and prevent atelectasis and pneumonia Multimodal analgesia in the form of nonsteroidal antiinflammatory drugs, narcotics, and neuraxial anesthesia may be needed Thoracic epidural analgesia has a controversial role in children, and its outcomes have not been rigorously described as in adults.40 It is unusual for children with isolated rib fractures to require ventilatory assistance In rare cases, multiple ribs in a single area may be fractured, producing a flail chest Specifically, this requires fractures of multiple contiguous ribs with at least points of fracture per rib, or fracture of the sternum, or dislocation of rib heads Flail chest results in paradoxical respiratory movement in which the thoracic wall over the flail segment collapses during inspiration, impeding ventilation of the lung The medial physis of the clavicle does not close until 23 to 25 years of age Falls from trampolines are associated with fracture of the clavicle; falls can lead to posterior sternoclavicular fracturedislocations in children This injury can be associated with dysphagia, dyspnea, and brachiocephalic compression Children with clavicular dislocations should be evaluated for injury to the esophagus and great vessels.41 Sternal fractures, although rare, are usually associated with blunt traumatic injuries They can result from MVCs, flexioncompression injuries, or direct blows They are classically, but rarely, associated with cardiac injury In fact, blunt myocardial injury is much more rare than other associated injuries; substernal hematoma and pulmonary contusions are most common In a 16-year case series of all radiologically confirmed sternal fractures at a pediatric level trauma center, only a single patient had cardiac contusion.42,43 Given the rarity of blunt myocardial injury, telemetry, cardiac enzyme evaluation, and echocardiography are typically reserved for adult patients with screening electrocardiogram abnormalities.44 There are insufficient data to provide more detailed guidance among children Ultrasound has a high sensitivity and specificity in the diagnosis of sternal fractures, especially among young, thin patients.43,45 Scapular fractures are uncommon in children, as a significant amount of force is required to fracture the scapula A careful neurologic and vascular examination should be performed, as axillary artery and brachial plexus injuries may be present In rare cases of chest trauma, an intercostal hernia may form, resulting in lung herniation Most hernias occur at a site of previous injury and are commonly seen at the anterior parasternal border because the cartilaginous junction to the sternum is absent Most are experienced after blunt trauma, particularly after multiple rib fractures or chondrocostal dislocation The hernia should be treated by direct surgical repair and may require mesh placement.46,47 Thoracoscopic hernia repair has been described.48 Lung and Airway Injury Pneumothorax (air in the pleural space) and hemothorax (blood in the pleural space) can both lead to respiratory compromise and subsequent cardiovascular collapse Occult pneumothorax is the least severe of these entities It is defined as air in the pleural space seen on CT but not visible on chest radiographs and without impaired ventilation or oxygenation Occult pneumothorax can be safely observed and does not necessitate tube thoracostomy.49 Careful consideration should be given to the possibility of pneumothorax expansion after beginning positivepressure ventilation; these patients may benefit from tube thoracostomy prior to intubation Minor pneumothorax produces mild clinical symptoms, including tachypnea, distress, and decreased oxygen saturation Pneumothorax may be suspected on physical examination when bruising or rib fractures are evident on the chest wall Asymmetry in breath sounds or chest wall movement should also raise suspicion Tension pneumothorax 1404 S E C T I O N X I I Pediatric Critical Care: Environmental Injury and Trauma occurs when an injured tissue (either lung parenchyma or chest wall) forms a one-way valve, allowing air to enter the pleural space and preventing air from escaping Tension pneumothorax results in rapid respiratory distress with distension of the affected side, contralateral displacement of mediastinal structures, and decreasing venous return with rapid decompensation and shock Tracheal deviation may be seen with tension pneumothorax, as the tension in the air-filled side leads to compression of the healthy lung and deviation of the trachea away from the side of the pneumothorax Any patient with a suspected pneumothorax and signs of respiratory or cardiac decline should receive immediate needle decompression of the chest cavity Needle decompression can be performed by placing an angiocatheter into the second intercostal space at the midclavicular line If a pneumothorax is encountered, the clinician should hear an immediate rush of air as soon as the pleural space is entered At this point, the needle should be removed but the catheter left in place while the patient is prepared for emergent tube thoracostomy The patient should be placed in the supine position with the arm in complete abduction This position widens the intercostal spaces, facilitating placement of the tube Tube thoracostomy should be performed by inserting an intercostal tube into the fourth or fifth intercostal space, in the midaxillary line At this level, there is little risk of injury to the long thoracic nerve A chest tube that is placed too low may inadvertently be placed below the diaphragm, with resultant injury to the liver, spleen, or intestines If urgency allows, ultrasound evaluation during the procedure may help prevent subdiaphragmatic placement.50 Careful attention should be given to avoid the neurovascular bundle, which runs directly below each rib A chest tube that penetrates the intercostal musculature directly above the fourth or fifth ribs has less chance of causing an intercostal arterial laceration An adequately large tube should be placed to facilitate drainage of air, fluid, and blood The tube should be connected to water seal drainage and suction to facilitate reexpansion of the lung (Fig 119.1) There are two major classes of tubes available at most centers for thoracostomy: surgical and percutaneous (“pigtail”) tubes Although few studies have prospectively evaluated differences in the acute trauma setting among children specifically, experience with pleural drainage among adult trauma victims generally attests to the equivalence of the two approaches for evacuation of Wall suction Thoracostomy tube A • Fig 119.1 Chest B C drainage system The first chamber (A) connects directly to the thoracostomy tube and allows for drainage of fluid from the pleural space The second chamber (B) creates a water seal, or one-way valve that permits air to exit the pleural space during expiration but prevents air from returning during inspiration The third chamber (C) regulates the amount of suction applied to the pleural cavity This chamber connects to wall suction, but the height of the water column is what controls the amount of suction air and fresh blood with respect to failure and complications However, clots and empyema may benefit from larger, stiffer conventional surgical chest tube placement.51 The benefit of selective application of smaller-caliber, flexible pigtail catheters includes less traumatic insertion and greater patient comfort.52 The majority of chest injuries resulting in pneumothorax or hemothorax require only a tube thoracostomy for successful management The pulmonary circulation operates at a low arterial pressure and bleeding is slow from tears in the lung parenchyma Hemostasis generally occurs as the lung reexpands through a combination of tamponade and intrinsic coagulation in the noncoagulopathic patient Even in cases of hemothorax without hemodynamic compromise or anemia, removal of blood from the pleural space is necessary to prevent lung entrapment as the hematoma expands or solidifies Furthermore, an empyema may develop in the nutrient-rich blood In cases of ongoing hemorrhage, the blood loss should be quantified Exsanguinating hemorrhage usually involves intercostal, hilar, or mediastinal vessels When the output is greater than 20% to 30% of the child’s blood volume or if the output exceeds to mL/kg per hour over the prior hours, then CT angiography (if the vessel is identified and amenable to percutaneous intervention on CT angiography) or thoracotomy should be performed for definitive hemostasis If a large air leak from a thoracostomy tube persists after several days, injury to the trachea or bronchi is likely This injury may require prompt intubation with fiberoptic bronchoscopy assistance Appropriate ventilation and healing may be achieved by passing the endotracheal tube beyond the site of the airway injury Unilateral intubation of the unaffected lung may also be used to aid healing or survival until the injury can be surgically repaired The trachea and bronchi may be injured in both blunt and penetrating trauma High-energy impact coupled with a closed glottis can produce elevated intraluminal pressures, causing rupture of the airway The airway and bronchial tree may also be disrupted during violent deceleration or rapid crush injuries The membranous portion of the trachea and bronchi are most susceptible to this type of injury Airway disruption at any level can cause pneumomediastinum and eventual pneumothorax and can be lifethreatening Up to one-third in the first hour may be lethal; urgent airway control, bronchoscopic diagnosis, and surgical intervention may be lifesaving.53 Pulmonary contusions most commonly occur after blunt trauma and are the result of high-energy application to the lung parenchyma High-energy trauma to the chest causes twice as many lung contusions in children than adults, with significantly fewer rib fractures.54 Pulmonary contusions may be present on the initial chest radiograph, but often blossom over time Contusion, hemorrhage, edema, and damage to the alveolar spaces can all occur and cause respiratory insufficiency However, very few children will require intubation for pulmonary contusions alone Pulmonary contusion in the pediatric population can lead to pneumonia (about 20%) but rarely causes acute respiratory distress syndrome (ARDS) as it does in an adult population.55 Traumatic pneumatocele is a cyst of uncertain etiology that develops in the lung parenchyma after trauma and is usually evident on radiography by days after injury The vast majority resolve spontaneously within to months and not require intervention, although larger lesions may be associated with rupture and pneumothorax or infection.56 Recent reports suggest that isolated pneumatoceles require no further imaging and no specific followup in otherwise well patients.57 ... but prevents air from returning during inspiration The third chamber (C) regulates the amount of suction applied to the pleural cavity This chamber connects to wall suction, but the height of... are most susceptible to this type of injury Airway disruption at any level can cause pneumomediastinum and eventual pneumothorax and can be lifethreatening Up to one-third in the first hour may... adults Decreased venous return may lead to shock and rapid death In the context of the rarity of this condition as well as the decreased reliability of physical examination, physicians who treat