In the evaluation of patients sustaining ballistic chest trauma, examination includes attention to jugular venous distension, expanding hematoma, decreased breath sounds, subcutaneous emphysema, air leak, and heart sounds. Witnessed cardiac arrest from penetrating thoracic trauma is a clear indication for emergency department (resuscitative) thoracotomy. Unstable patients should have a 36 to 40 French chest tube placed on the side of injury. Upright chest radiographs (supine if vertebral injury is suspected) are obtained to assess the tract of the missile, hemopneumothorax, pneumomediastinum, enlarged cardiac silhouette, and underlying pulmonary contusion. (CD,Figureii7)
CD Figure 7. This young male suffered a gunshot wound to the right back. The chest radiograph (a) reveals a right pneumothorax and the bullet resting over the mediastinum. A lateral film is necessary to reconstruct the path of the missile accurately and to determine which organs are at risk. The trachea, esophagus, lungs, and thoracic vessels require evaluation. The arch aortogram (b) reveals an injury to the brachiocephalic artery, mandating exploration.
Hemopneumothorax is the most common injury and 85 per cent of patients can be treated with tube thoracostomy alone. If more than 1500 ml of blood is immediately returned, thoracotomy is usually indicated. Cardiac, pulmonary, great vessel, or intercostal vascular injury is frequently found. If the patient continues to bleed at more than 300 ml/h, exploratory thoracotomy must be considered. The hemothorax must be completely drained by placing additional chest tubes or using thoracoscopy. (CD Figure 8)
CD Figure 8. This young female suffered a stab wound to the right chest with a resultant hemopneumothorax. Failure to re-expand the lung may result in continued bleeding, continued air leak, and increased risk of pneumonia and empyema. The volume of hemorrhage and ongoing bleeding cannot be accurately assessed until the hemothorax is completely drained. Methods for draining the chest include additional chest tubes and thoracoscopy.
A fully expanded lung may tamponade bleeding and reduce the risk of empyema and resultant fibrothorax. If full lung expansion is not obtained after placement of two functioning tubes, tracheobronchial injury should be suspected and bronchoscopy performed. Occasionally the chest tube will recover a patient's tidal volume and severe dyspnea will ensue, suggesting major airway or pulmonary injury for which further investigation such as bronchoscopy or thoracotomy is indicated. Deterioration after positive-pressure ventilation may be due to conversion of a simple to a tension pneumothorax or an air embolus secondary to traumatic bronchovenous fistula. Severe hypoxia requiring intubation may result from pulmonary contusion, pneumothorax, hemothorax, or aspiration of blood. If there are no contraindications, a nasogastric tube is placed and the return of blood should raise suspicions for esophageal or gastric injury. The standard assessment of transmediastinal injuries consists of either exploratory thoracotomy or a combination of arteriogram, esophagoscopy, bronchoscopy, and echocardiography ( Mattoxet.
al 1996). Currently, support for exploratory thoracoscopy in this patient population is growing. However, the ability of this new modality to detect occult cardiac or esophageal injury awaits conformation from prospective trials (Sjmon.and Ivatury .. . 1995). In patients with tangential or peripheral chest wounds and a normal initial chest radiograph, the study must be repeated after 6 h in order to detect delayed pneumothorax, which has an incidence approaching 10 per cent. If the second study is normal, the patient is discharged.
Penetration of the anterior mediastinal rectangle (bounded by the sternal notch, the xiphoid, and the nipples) places the patient at risk of cardiac injury and tamponade. Beck's triad of distended neck veins, hypotension, and muffled heart sounds is present in only 10 per cent of cases; therefore all injuries must be fully assessed. Measurement of central venous pressure can be useful in differentiating hemorrhagic shock from tamponade. Chest radiographs may reveal an enlarged cardiac silhouette or pneumopericardium. Echocardiography, either transthoracic or transesophageal, may reveal the presence of fluid in the pericardium, necessitating exploration via either the subxiphoid window or thoracoscopy. Pericardiocentesis is of limited use in the trauma setting.
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