Blunt thoracic trauma

Abstract

Thoracic trauma is uncommon in children, comprising only 0.2'7% of all injuries encountered in the pediatric population. 1'7 The vast majority of these injuries are secondary to blunt force.1,4,8'11 Despite the relatively low incidence of thoracic injuries in children they tend to be associated with a high morbidity and mortality.1,2,4'6,9'13 Most of these injuries are motor vehicle related ranging from 48.1 to 91.7%.1,4,9'13 The child is most often a pedestrian rather than an occupant of the vehicle.1,4,9,11'13 The experience of the Royal Children's Hospital in Melbourne is similar to that of other international series. In the 5 years between 2000 and 2005 this hospital has admitted 138 children with thoracic injuries comprising 1.7% of all trauma admissions in that time period. These were predominantly due to blunt force trauma (92.8%). Most of the injuries were motor vehicle related (54%). Within the motor vehicle group 61% were occupants of the motor vehicle while 39% were pedestrians hit by a car. This ratio is weighted more toward passengers rather than pedestrians compared to the international literature. Other relatively frequently occurring mechanisms were motorbike related (11%), collision (7.7%), and animal related (7%) (Table 16.1). Thoracic injuries caused by a blunt mechanism may present diagnostic difficulties when there are no external signs of trauma. This is in contrast to penetrating chest injuries, discussed in the following chapter. In both situations the patient may demonstrate few clinical signs. However, in cases where there has been a penetrating injury there will always be a wound to alert the clinician to the possibility of an intrathoracic injury. There are a number of important anatomical and physiological differences between the pediatric and adult thorax. These differences significantly influence the injury patterns seen in children who have sustained chest trauma. The chest wall of a child is very compliant. As a consequence, the bony skeleton is massively deformable to the degree that the anterior ribs can be depressed until they make contact with the posterior ribs without fracturing. This means that the intrathoracic structures may be significantly compressed without any overlying injury evident. It also suggests that the mechanisms required to cause fractures of these bones must involve substantial force. Children with suspected thoracic trauma initially require assessment of their airway and breathing. Rarely a thoracic injury will involve trauma to the upper airway resulting in obstruction. In such cases a patent airway must be secured urgently prior to further clinical assessment. The majority of thoracic injuries encountered will impact primarily on the patient's respiration and ventilation. Radiological investigations will always involve a chest X-ray (CXR), which should be completed in the basic trauma series. If the patient is hemodynamically stable and further information regarding the extent of any injury is required a computed tomography (CT) scan of the chest should be undertaken. In one prospective study a CT scan in the initial diagnostic work up of blunt thoracic trauma accurately diagnosed thoracic injuries, influenced the therapeutic management, and was found to be more sensitive than CXR.14 Another study, however, concluded that although CT was a highly sensitive diagnostic modality and influenced the thoracic injury management, a CXR still provided valuable information and CT should be reserved for selected cases.15 Given the high dose of radiation associated with pediatric CT scans and the evidence suggesting a fatal malignancy rate of 1 per 1,000 scans16 this investigation should be used judiciously. Management of any pediatric patient who has suffered thoracic trauma involves the application of supplemental oxygen, close monitoring, good analgesia, and regular chest physiotherapy. Insertion of a nasogastric tube is also important in order to reduce the massive gastric dilatation commonly encountered in these patients (Fig. 16.1). The majority of children with blunt thoracic trauma can be managed nonoperatively.