Chest Thoracic Trauma Children

Thoracic trauma is considered an infrequent problem in children, with an estimated incidence of 10% even   in communities with a relatively high level if interpersonal violence (Stafford and Harmon 1993). This figure does not reflect the true significance thoracic trauma. Detailed assessment of paediatric trauma deaths indicates that up to 27% will have thoracic injuries following blunt trauma (Eichelberger and Randolph 1981). As the quality and speed of pre-hospital care continues to improve, it seems likely that more of these children will reach hospital and require urgent management of their chest injuries (Allhouse et al. 1993, Sheikh and Culbertson 1993, Michaels et al. 1997, Mordehai et al. 1997). In this respect chest trauma appears to act as a marker of injury severity (Peclet et al. 1990, Reilly et al. 1993). The mortality following blunt trauma increases to 25% in those children with a thoracic injury compared to just 1.5% in those without (Allhouse et al. 1993). These injuries are rarely isolated, however, with children often sustaining additional injuries to the head, abdomen and lower limb: the combination of thoracic and head injury is the most frequently associated with a fatal outcome (Stafford and Harmon 1993, Wright 1995, Allhouse et al. 1993, Peclet et al. 1990). Thoracic trauma may not be the presenting injury but should also be actively excluded in patients with injuries to adjacent systems, particularly in penetrating trauma of the neck and abdomen and with blunt injuries to the larynx. The distribution in severity of thoracic injuries in children is bimodal, with many injuries being minor such as bruises and simple abrasions of the chest wall. At the other extreme are high-speed road traffic accidents and injuries that include severe pulmonary contusions, pulmonary and tracheobronchial lacerations. A significant subgroup of patients is those with iatrogenic thoracic injuries, particularly those which occur during treatment of the trauma patient, such as haemothorax after insertion of an intercostal catheter or pnemothorax following insertion of central venous catheters (American College of Surgeons 1997, Barrett et al. 1998). Whilst the majority of thoracic injuries are minor, the clinician assessing the child with chest trauma should not be lulled into a false sense of security by the initial haemodynamic stability of the child and the apparent lack of associated injuries. Rather, they should be extremely cautious of any thoracic trauma in the paediatric age group, when cardiopulmonary reserve may mask the true severity of the injury and in a setting in which severe associated injury is common (Stafford PW and Harmon 1993, Kissoon et al. 1990, Lloyd-Thomas et al. 1996). Key points

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10% of all paediatric trauma but 27% of paediatric trauma deaths

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Associated injuries, especially head injuries, common

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Bimodal distribution of severity of injury

Pleuropulmonary injuries Trauma to the pleura and underlying structures is indicated by a pneumothorax, haemothorax or

haemopneumothorax and is a common injury. There is a tendency to regard these terms as a diagnosis rather than a description of blood, air or a combination of the two in the pleural cavity. While many may be adequately treated by insertion of an intercostal catheter in order to drain the pleural cavity and allow reexpansion of the lung, the clinician should not lose sight of the true location of the injury. In addition to the pleura, it must be lung, chest wall or mediastinal structures that have been damaged. Pneumothorax is the most common finding in both adults and children, but the incidence of tension pneumothorax is much higher in children because of the increased mobility of the mediastinum (Eichelberger and Randolph 1981, Allhouse et al. 1993, Rowe et al. 1995). Therefore rapid and definitive initial treatment with an intercostal catheter is recommended. In the preschool child breath sounds can be transmitted across the chest, so an increased percussion note and lack of chest wall movements on the affected side may be the only reliable indicators of a simple pneumothorax. Haemothorax is less common in children because of the lower incidence of rib fractures but may more frequently result from iatrogenic damage during chest drain insertion because of the smaller intercostal space. Haemothorax prior to insertion of a chest drain usually follows severe trauma in most children and a significant underlying injury should be expected (Allhouse et al. 1993). The thorax may also be a site of occult blood loss, in addition to the abdomen and pelvis, in a haemodynamically unstable child (Allhouse et al. 1993, Lloyd-Thomas et al. 1996). If a blood volume of greater than 30% of the child’s circulating volume is initially drained from the chest, or there is on ongoing loss equivalent to 20 to 30 mL/kg/hour for more than 2 to 4 hours, surgical exploration is indicated (Rowe et al. 1995). The blood should be drained from the pleural cavity once the diagnosis has been made: delayed treatment beyond 3 to 5 days may result in fibrinous adhesions and trapped lung with subsequent restrictive lung disease and a scoliosis as the child grows (Eichelberger and Randolph 1981, Allhouse et al. 1993). Pneumomediastinum is an uncommon finding following trauma but may represent a paramediastinal air cyst following pulmonary injury, an underlying tracheobronchial injury or an oesophageal perforation (Bednarkiewicz et al. 1993). The difficulty is to distinguish the benign alveolar injury giving rise to paramediastinal air that may be treated conservatively, from the more serious trauma involving the oesophagus or respiratory tract. In this situation contrast studies, Computerized Tomography or bronchoscopy may be required. Pulmonary contusions are the most common thoracic injury in children, but may be difficult to diagnose initially because of few signs and symptoms (Allen and Cox 1989). They represent a parenchymal injury to the lung characterized by haemorrhage and oedema, making the lung less compliant, increasing ventilation/perfusion mismatch because of arteriovenous shunting, impairing gas exchange and predisposing to pneumonia and respiratory distress syndrome. The elasticity of the chest wall in children allows for highly effective transmission of the force of the trauma to the lung parenchyma with minimal or no external signs of injury (Lloyd-Thomas 1996, Rowe et al. 1995, Tepas et al. 1996). Although these injuries are usually eventually diagnosed with progressive opacification in the region of the

injured lung on plain radiology, the initial chest radiograph may be completely normal even on subsequent review (Allen and Cox 1989). Early clinical signs include impaired oxygen saturation and mild tachypnoea, which may progress rapidly to severe hypoxia requiring ventilation. Plain radiographic changes lag behind the clinical progress of the contusion and frequently underestimate the extent of the injury (Allen and Cox 1989, Sivit et al. 1994) Computerized Tomography expedites diagnosis and allows for a more accurate assessment of the extent of the injury but rarely directly influences clinical management (Sivit et al. 1989). Treatment is supportive and involves the use of warmed, humidified supplementary oxygen, chest physiotherapy with incentive spirometry and close observation in a high-dependency environment to monitor resuscitation. A paediatric intensive care physician should be involved early in the assessment and management of these patients, who should be reviewed at least 2 hourly in the first 12 to 24 hours. Those patients who continue to deteriorate should be transferred to an intensive care unit and mechanical ventilation introduced with Positive End Expiratory Pressure. Loop diuretics such as frusemide may be effective in reducing pulmonary oedema, but should only be used in conjunction with central venous pressure monitoring to avoid hypovolaemia. In a severe case refractory to conventional management, alternative ventilatory strategies may be required. Some of these are based on experience obtained in neonates with diaphragmatic hernia, including oscillation and nitric oxide. The role of steroids in these injuries remains controversial (Allen and Cox 1998). Pulmonary laceration is a rare injury in children as significant penetrating injuries, either from a foreign body or fractured rib, are uncommon. Clinically there is haemoptysis in addition to signs of local injury. There is usually evidence of haemopneumothorax on a chest radiograph, although this may be difficult to interpret on a supine film. Clinically, as haemorrhage continues, cardiovascular instability occurs. Treatment is surgical and involves thoracotomy and lobectomy in order to stem the blood loss. Autotransfusion may be a useful adjunct in the management of these rare patients (Kharasch et al. 1994). Key points •

Pulmonary contusions most common injury

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Tension pnemothorax more common than in adults due to mediastinal mobility

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Haemothorax less common than adults but blood loss may be haemodynamically significant in children

Tracheobronchial injuries These injuries are frequently associated with a fatal outcome and it is fortunate therefore that they are rare (Stafford and Harmon 1993). There is some evidence, however, that bronchial injury may be more common in children than adults due to differences in chest wall compliance (Mordehai et al. 1997). Tracheobronchial injuries typically occur in children following rapid deceleration and severe blunt chest trauma in a road traffic accident or following penetrating chest trauma. These injuries are frequently difficult to diagnose but should be suspected in a trauma patient with a pneumothorax that does not respond to an

intercostal catheter (Rowe et al. 1995). The diagnosis should be confirmed by bronchoscopy and the treatment is usually primary repair via a thoracotomy, although an incomplete injury in a patient with blunt trauma that responds to the initial chest drainage may be treated conservatively. Cardiovascular injuries Significant cardiac injuries and trauma to the major vessels in the chest are rare following blunt trauma in children and may be difficult to diagnose even when there is clinical suspicion. In general the pattern of injury, diagnosis and management are similar to adult patients. Myocardial contusions are uncommon in children although this may be related to under-reporting, as there are no clearly defined diagnostic criteria (Langer et al. 1989). Certainly myocardial contusions requiring medical intervention or support for significant arrhythmias are rare, although minor ECG abnormalities and elevated cardiac enzymes may occur in up to a third of paediatric patients with blunt thoracic trauma (Stafford et al. 1993). This would seem plausible given the ability of the chest wall in children to transfer the energy associated with the injury to the lung parenchyma, resulting in a high incidence of pulmonary contusions. Thus the finding of severe pulmonary contusions, rib or sternal fractures should alert the clinician to the possibility of myocardial injury. Rarely a powerful direct blow to the chest will result in refractory ventricular fibrillation (van Amerongen et al. 1997). Other cardiac injuries that have been described include pericardial tamponade from air or blood, ruptured interventricular septum, papillary muscles damage leading to valvular disruption and ventricular rupture (Michaels et al. 1997, Harel et al. 1995). Delayed pericardial tamponade may occur up to two weeks after blunt thoracic trauma in children (Bowers et al. 1994). Tamponade may now be rapidly diagnosed as part of the FAST (Focused Assessment for the Sonographic examination of the Trauma patient) examination in patients with multiple trauma (Wright et al. 1995, Rozycki et al. 1998). More accurate imaging of the heart may be obtained via precordial or transoesophageal echocardiography, although in children the latter will require general anaesthesia (Wright et al. 1995, Pretre and Chilcott 1997, Grasso and Keller 1998). Major vessel injuries are probably as common in children as adults after allowing for differences in number of journeys and speed of travel, although the greater mobility of the mediastinal structures in children increases the risk of major injury and most are dead at the scene (Stafford et al. 1993, Eddy et al. 1990). Aortic transection typically occurs as a result of rapid deceleration in road traffic accidents. Usually the patient is unrestrained in a motor vehicle and the accident involves speeds of over 55mp/h, or on a motorbike that hits a stationary object (Eddy et al. 1990). The diagnosis is suggested by the combination of an abnormal chest radiograph and an appropriate mechanism. Plain radiographic signs of aortic injury include widened mediastinum, tracheal or gastric tube deviation, a left apical cap, effusion or haemothorax and depression of the left main bronchus (Stafford et al. 1993, Pretre and Chilcott 1997). The diagnosis is confirmed on aortography, although the use of magnetic resonance angiography or transoesophageal echocardiography has been described, with the latter perhaps more accurate in delineating intimal tears and flaps than aortography (Wright et al. 1995). In the patient with a suggestive mechanism of injury but a

normal chest radiograph, a thoracic CT with intravenous contrast is this most appropriate investigation to exclude an aortic injury (Pretre and Chilcott 1997). Other vascular injuries include subclavian vessel trauma in association with first rib fractures. This pattern of injury implies considerable force and associated injuries are correspondingly severe (Harris and Soper 1990). The diagnosis may be suspected on the basis of neurovascular signs and symptoms in the upper limb of the affected side but should be actively excluded by directed examination once a first rib fracture has been documented. The extent of the vascular injury should then be determined by angiography and a vascular surgeon involved in subsequent management. Venous injuries most commonly represent iatrogenic injuries following operative intervention for insertion of a central venous catheter. These are usually identified at the time of insertion of the catheter but occasionally the line may later migrate through the atrial wall to produce a haemopericardium (Barrett et al 1998). The thoracic duct may be injured during neonatal thoracotomy for repair of a tracheo-oesophageal fistula or patent ductus arteriosus, or rarely in a hyperextension injury to the cervical spine (Eichelberger et al. 1981). The result is a chylothorax that may initially be treated with an intercostal catheter and parenteral nutrition. If this treatment fails, open ligation of the duct is required. Key points •

Rare in children and difficult to diagnose

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Investigation and management similar to adults

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Diagnosis of cardiac tamponade rapidly confirmed by FAST examination

Oesophageal injuries Oesophageal injuries occurring as a result of blunt or penetrating trauma to the thorax are rare. Perforation is usually seen following instrumentation or accidental ingestion of a sharp object (Rowe et al. 1995). The key to the diagnosis is the onset of moderate to severe chest pain in association with a combination of indicative history, pneumothorax, pneumomediastinum, surgical emphysema or a pleural effusion. Chest pain in any child after oesophageal instrumentation should never be ignored. Chest wall injuries The high compliance of the chest wall in children allowing transfer of energy to underlying structures results in a relatively low incidence of rib and sternal fractures (Tepas et al. 1996). Correspondingly, when a fracture is identified, this usually implies that a considerably force has been applied and a significant intra-thoracic injury should be assumed. Isolated rib fractures following point application of a force, such as

a fall onto the edge of an object, may not be associated with serious injury (Allshouse et al. 1993). Rib fractures are not infrequently seen in cases of child abuse and the finding of multiple fractures of varying age should raise the index of suspicion (Carty 1997). First rib and scapular fractures, because of their location and surrounding musculoskeletal support, represent particularly severe injuries with a high likelihood of vascular and pleuropulmonary involvement (Harris and Soper 1990). Multiple fractures leading to a flail segment are fortunately rare and usually associated with a crush injury from an object falling onto the child from a height, such as a bookcase or heavy ornament (Tepas et al. 1996). The severe pulmonary contusions coupled with the flail segment inevitably result in hypoxia and respiratory failure requiring stabilization and mechanical ventilation. These patients would routinely require admission to a paediatric intensive care unit. Rib fractures may be diagnosed clinically and oblique view radiographs of the chest wall are not required for diagnosis or treatment. A chest radiograph is essential to help determine the presence of associated injuries. In the case of child abuse, a bone scan should be obtained to document the multiple fractures at different stages of healing. Treatment of isolated rib fractures is supportive with adequate analgesia and chest physiotherapy. A paediatric anaesthetist should be involved early to optimize the management of pain by appropriate use of non-steroidal anti-inflammatory analgesics and nerve blocks (Stafford and Harmon 1993). This enables effective chest physiotherapy and minimizes respiratory complications. Key points

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Compliant paediatric chest wall results in low incidence rib fractures

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Force of injury in children transmitted to underlying structures

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First rib fractures associated with neurovascular injuries

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Multiple rib fractures of different age associated with non-accidental injury

Diaphragmatic injuries Diaphragmatic injuries following blunt trauma occur as a result of a direct blow to the lower chest or upper abdomen. This produces a rapid rise in intra-abdominal pressure, tearing the diaphragm and allowing the potential migration of abdominal contents into the chest. The injury is much more common on the left side, presumably because of splinting by the liver on the right. In part, however, this difference might represent under-diagnosis of right-sided defects that remain supported by the liver. Occasionally minor trauma may ‘unmask’ a small congenital diaphragmatic hernia previously plugged by the spleen or kidney. The main difficulty in diaphragmatic injuries is in making the diagnosis. Whilst a chest radiograph may reveal disruption of the smooth contour of the diaphragm and the presence of abdominal viscera in the chest, the appearance is rarely this obvious. Passage of a gastric tube and subsequent radiography will help reveal the site of the stomach, but its intra-abdominal location does not exclude a diaphragmatic tear.

The diagnosis may be obtained by screening of the diaphragm fluoroscopically, ultrasound scanning or computerized tomography. None of these modalities are specific, however, and the injury may even be missed at laparotomy. If there is a high index of suspicion, an excellent view of the diaphragm is afforded by laparoscopy or thoracoscopy, with the option after confirming the diagnosis of performing the repair using these minimally invasive techniques (Graeber and Jones 1993, Liu et al. 1997). Most paediatric surgeons in the acute setting would favour performing a direct repair via the abdominal route as this allows easy reduction of viscera and inspection for associated intra-abdominal injuries. Key points

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Diaphragmatic injuries may be difficult to diagnose on CXR, CT scan, and even at laparotomy.

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Laparoscopy/thoracoscopy are the diagnostic modalties of choice when there is high clinical suspicaion as they afford the option of minimally invasive treatment after diagnosis.

Specific injury complexes Penetrating trauma Penetrating trauma as a result of interpersonal violence is rare in the United Kingdom and Australia, but is increasingly seen amongst older children and adolescents in the United States and South Africa. Children may be inadvertent victims of domestic violence, civilian or wartime conflict. In these circumstances the potential for serious injury is obvious. The much more common injury seen is the apparently minor penetrating wound resulting from a fall onto a piece of glass, or a twig breaking the skin after sliding down a tree. The chest wall is very thin in children and any object that breaks through the skin should be assumed to have penetrated the chest cavity. These apparently minor wounds should not be simply closed directly in the emergency department. Formal exploration should be performed in a controlled environment in all cases (Wright 1995). As a minimum investigation a chest radiograph should be performed with subsequent treatment dictated by the result (Grasso and Keller 1998). Traumatic asphyxia Traumatic asphyxia is a specific and clearly defined injury complex seen relatively frequently in children (Eichelberger and Randolph 1981, Kissoon et al. 1990). The usual scenario is that of a ‘back-over’ injury of a preschool child playing on the driveway at home. Because of the relatively low speed of the vehicle and the springy and compliant chest wall, rib fractures are uncommon. The lack of valves within the superior and inferior vena cavae allows the pressure rise to be transmitted to the head and neck area and the liver. This results in the appearance of multiple petechiae in the drainage area of the superior vena cava, with evidence of subconjunctival and retinal haemorrhages, and occasionally acute hepatomegaly. The danger of these injuries is usually from the combination of cerebral oedema and secondary hypoxia as

a consequence of pleuropulmonary injuries, typically pulmonary contusions or pneumothorax. Both give rise to confusion and disorientation that may make resuscitation of the child and its assessment difficult. Treatment is directed toward the underlying injury, but as these children usually require intensive monitoring they should be treated in a high dependency or intensive care area. Burns Burns are a common injury in childhood and the chest may be involved either directly as a result of burns to the chest wall or indirectly from an inhalational burn. In toddlers the most frequent injury is a burn to the upper chest and neck from a hot drink that the exploring child has pulled onto itself. These burns are often partial and infrequently compromise the airway. In older children, particularly boys experimenting with petrol or fire, major burns to the torso can occur. These injuries can severely compromise oxygenation as a result of an inhalational burn and splinting of the chest wall because of extensive cutaneous burns. The key issues in the management of these patients are to establish the airway early, as this may rapidly deteriorate due to oedema, and to commence warmed humidified supplementary oxygen. The arterial blood gases should be checked and a carboxyhaemoglobin level obtained if carbon monoxide poisoning is suspected following burns in a confined space, such as a house fire. Respiratory distress syndrome may develop in children with inhalational burns, and there is some evidence in adults that exogenous surfactant may improve outcome (Pallua et al. 1998). In circumferential burns involving the upper torso, escharotomies to release the tourniquet effect of the burnt skin should be performed to allow adequate excursion of the chest wall for ventilation. These patients should be managed in a specialized paediatric burns unit with intensive care facilities, so that both the burn and the child can be optimally treated. Whilst early grafting minimizes pain, the depth of the burn is often difficult to assess initially in children whose thin skin is more susceptible to thermal injury than adults. In those patients requiring grafting, great care should be taken to preserve the undeveloped breast bud during debridement, especially in girls (Garner and Smith 1992). Extended care is normally required in children with burns, both in terms of the functional result and scar management. Children are a dynamic platform because of growth and development, so regular re-evaluation of the result of burn management is required. Summary Thoracic trauma in children acts as a marker for severe injury and is usually associated with multi-system trauma, particularly head injuries. There is a potential for rapid deterioration that may initially be masked by the cardiovascular reserve of a normal child. Whilst severe injury is uncommon, it is a significant cause of mortality and morbidity. The majority of injuries may be managed by standard interventional measures with a successful outcome providing allowances are made for the differences in anatomy and physiology of children. Key points •

Thoracic trauma a marker for injury severity in children

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Usually associated with multisystem trauma

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Potential for rapid deterioration after cardiovascular reserve exhausted