Thoracic injuries in childhood

Published on 23/06/2015 by admin

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3.3 Thoracic injuries in childhood

Phil Aplin

Essentials

1 Thoracic injuries in children are common, are usually due to blunt trauma and are often associated with other injuries.
2 The pathophysiological differences in children depend principally on their age and size. These must be appreciated in order to optimise outcome.
3 The most common injuries are pulmonary contusions, rib fractures, pneumothoraces and haemothoraces. These can usually be managed by a combination of adequate oxygenation, IV fluids, thoracostomy tube drainage and analgesia.
4 Injuries to the aorta and diaphragm may be clinically occult and CXR findings are often non-specifically abnormal. Further diagnostic evaluation is always indicated in suspect cases.
5 Surgical intervention is uncommonly required, but is indicated in cases of massive haemothorax, cardiac tamponade, major airway and oesophageal injury, as well as in aortic and diaphragmatic injuries.
6 ED thoracotomy is principally indicated in cases of penetrating chest trauma and an arrest or pre-arrest presentation.

Introduction1–4

Traumatic injury is the most common cause of morbidity and mortality in childhood and thoracic injuries are secondary to head injuries as a cause of mortality. Isolated chest injuries have a mortality of around 5% but this increases substantially when combined with head and/or abdominal injury to as high as 20%. Injuries to the great vessels, bronchi, lung lacerations and cardiac tamponade are the chest injuries most likely to cause early death. Small children provide a small target in blunt trauma, so multiple injuries should be expected.

A recent review of an Australian trauma registry database found multiple body region injury to be almost universal (99%) in cases of severe blunt chest trauma. The most frequent associated serious injuries were head (46%), lower extremity (32%) and abdominopelvic injury (30%). By far and away the commonest chest injuries were pulmonary contusion, haemopneumothorax and rib fractures.

The common mechanisms of injury vary with the age of the child. Overall, the majority (60–80%) are due to blunt trauma and involve a motor vehicle in over half. In infants and toddlers common mechanisms include being injured as passengers in motor vehicle collisions (MVC) or as pedestrians struck or run over by a vehicle (commonly in the driveway of the family home). Falls (from stairs, balconies, etc.) occurs mainly in this age group. Child abuse also tends to predominate in this age group and should always be considered. In school age children motor vehicle and bicycle related trauma is common and sporting (± extreme sports) injuries increase in frequency with age. With adolescence the occurrence of penetrating trauma emerges with an associated increased mortality risk, also inexperienced teenage drivers have an increased incidence of MVC. Drug and alcohol intoxication is often associated with personal/interpersonal violence in this older age group.

There are a number of anatomical and physiological features of small children that must be appreciated when managing paediatric chest trauma. These are summarised in Table 3.3.1.

Table 3.3.1 Important pathophysiological differences between children and adults in chest trauma

• Small target – multiple injuries common
• Narrow airway – prone to obstruction
• Anterior larynx – difficult intubation
• Increased surface area – increased risk of hypothermia
• Increased oxygen consumption, diaphragmatic breathing, low functional residual capacity – prone to hypoxia
• Increased pliability of ribs – decreased incidence of rib fractures
• Response to blood loss – hypotension is a late sign of shock
• Developmental considerations – paediatric coma scoring

Initial approach in the ED5

Initial management follows the usual priorities. After ensuring airway patency, breathing should be assessed. High-flow oxygen should be applied. Signs of respiratory compromise and tension pneumothorax should be managed by needle decompression prior to chest X-ray (CXR) followed by chest tube insertion. A large haemothorax may compromise ventilation as well as circulation, requiring early chest tube placement and fluid resuscitation, whilst an orogastric tube (OGT) should be placed early to decompress the stomach, as gastric distension may compromise ventilation. Mechanical ventilation should be instituted for signs of ongoing respiratory distress/respiratory failure not relieved by optimisation of oxygen delivery, chest tube insertion, closure of open chest wounds and OGT placement. Ongoing signs of circulatory compromise without evidence of blood loss should raise the possibility of cardiac tamponade and myocardial contusion in a child with chest injuries. A portable CXR should be the first radiological test ordered. FAST (focused abdominal scan in trauma) scanning should occur early in the resuscitation of a child, where available, and imaging of the pericardium should always be included to detect haemopericardium. The vast majority of chest injuries in childhood can be managed non-operatively. Drainage of pericardial blood may occasionally be performed in the emergency department (ED) in an unstable patient if operative intervention is not immediately available. Other indications for operative intervention are listed in Table 3.3.2. CT imaging of the chest should be used selectively. It is indicated in high impact trauma and when multiple injuries are present or suspected, particularly severe head injury where there is a high likelihood of associated severe chest injury.

Table 3.3.2 Indications for operative intervention in chest trauma

• Great vessel injury
• Pericardial tamponade
• Large haemothoraces
• Tracheobronchial injuries
• Oesophageal injury
• Diaphragmatic lacerations
• Open pneumothorax with major chest wall defect
• Penetrating chest trauma that crosses the mediastinum

Once stabilised, thoracic CT scan may be indicated to further delineate the extent of pulmonary injury, evaluate the great vessels and detect pneumothoraces. Analgesia should be initiated early in appropriate doses.

Chest wall injury6

Rib fractures

The elasticity and flexibility of the younger child’s chest wall leads to a lower incidence of rib fractures. Significant underlying intrathoracic injury can occur in the absence of rib fractures. In the 0- to 3-year age group rib fractures should raise the concern of abuse: in one study 2/3 of 0–3-year-olds with rib fractures were victims of abuse, and a careful assessment of all aspects of the clinical presentation is mandatory. Radiological findings suggestive of abuse include: multiple fractures, fractures of varying ages and bilateral fractures. A bone scan is a more sensitive test in the setting of potential abuse.

Rib fractures in children are a marker of potential severe associated injuries. Multiple rib fractures (>1) increase the risk of severe intrathoracic injury, multiple injuries and mortality. Fracture of the first rib requires significant force, mandating a high degree of suspicion of associated injuries to the great vessels and the trachea.

Flail chest injuries are rare in children and clearly indicate serious injury, with reduced ventilatory effectiveness and associated lung contusions contributing to the significant potential for respiratory failure. Assisted ventilation is indicated for those with respiratory failure despite optimal non-invasive ventilation and analgesia or associated injuries, particularly to the head.

Management of rib fractures involves analgesia, treatment of associated injuries, ongoing assessment of the child’s respiratory status and close observation for complications that may arise. Analgesic options in the ED include oral paracetamol (also available intravenously (IV)) and anti-inflammatories, intranasal fentanyl and titrated IV narcotics. Prevention of atelectasis and pneumonia is a priority.

Pulmonary injury7,8

Contusion

In children it is important to appreciate that significant lung injury can occur in the absence of rib fractures or other external signs of chest wall injury. Pulmonary contusion most commonly results from blunt injury and requires significant force. Pathological findings are intra-alveolar haemorrhage, consolidation and oedema causing V/Q mismatch, reduced lung compliance and subsequent hypoxaemia. CXR findings of increased pulmonary opacity may be present in the ED but may evolve over time. Computerised tomography (CT) scanning of the thorax may reveal contusion that is not evident on the initial plain films. Approximately half of the CXRs showing pulmonary contusion show other abnormalities, most commonly fractured ribs and pneumo/haemothoraces.

Management of pulmonary contusion involves:

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