Physical Examination

Expeditious inspection and palpation of the chest will provide much information regarding the patient’s injuries (Figure 1). Auscultation and percussion tend to be less reliable due to the high ambient noise of the trauma ED. Hypotension, tachycardia, pallor, or cyanosis suggests shock. In the presence of a known or suspected thoracic injury, shock must be assumed to be from an intrathoracic source. Inspection of the chest itself should include assessment of use of the accessory muscles suggestive of airway obstruction, the symmetry of the chest wall, number and location of wounds, presence of open chest wounds, subcutaneous emphysema, and the presence of “flail” segments. While tracheal deviation in the neck is also frequently cited as a sign of tension pneumothorax, in reality it is rarely if ever seen, even in patients with gross mediastinal deviation on chest x-ray. Palpation can reveal mobile segments of chest wall and further allows appreciation of the symmetry of chest wall motion and of crepitance. Auscultation in trauma has a high specificity but very poor sensitivity, so focus should be placed only on the presence and symmetry of air entry. Heart sounds, such as the muffled heartbeat in Beck’s triad or the “mediastinal crunch” of Hamman’s sign, are also difficult to obtain clearly in the trauma bay. The absence or asymmetry of breath sounds, however, is very suggestive of significant pathology; in the unstable patient, this is an indication for intervention on clinical grounds and a contraindication for imaging studies. Thoracic percussion, even more than auscultation, is difficult to interpret in the trauma setting and is rarely useful.

Figure 1 Physical examination of the chest in a driver of a motor vehicle discloses marked asymmetry of the right and left hemithoraces.

Physical examination often, but not always, reveals the presence of a hemopneumothorax. It may be suspected in hemodynamically unstable patients by physical exam. In the patient with greatly diminished or absent breath sounds on the affected side, the diagnosis is quickly made on clinical grounds. In the noisy trauma bay, however, auscultation can unreliable even in the presence of a sizeable hemothorax or pneumothorax. In addition, breath sounds can be well-transmitted from the contralateral lung, further obscuring the results of auscultation. The finding of any subcutaneous emphysema following blunt trauma or at some distance from a penetrating wound is ample evidence of a pneumothorax that requires treatment. An open pneumothorax, of course, is readily appreciated on examination. Confirmation of the hemothorax or pneumothorax occurs with the placement of a chest tube with evacuation of blood and/or air.

Radiographic Studies

The supine AP CXR is the initial and sometimes most important study in the management of chest trauma. The trauma surgeon must be comfortable interpreting these films, which are often sub-optimal due to the patient’s body habitus, supine position, the presence of a spine board, and the use of portable x-ray machines. Still, the portable AP CXR can diagnose or exclude a number of life-threatening injuries, and it must be obtained and reviewed before the patient is transported for any other imaging or procedures.

Interpretation of the CXR should begin with review of the lung parenchyma and pleura. Lung expansion, pulmonary infiltrates or contusions, the position of the endotracheal tube if present, and the presence of hemothoraces or pneumothoraces should be noted. The mediastinum should be evaluated for evidence of great vessel injury, which is suggested by mediastinal widening, blunting of the aortic knob, apical capping, or a medial displacement of the left mainstem bronchus or of the nasogastric tube. Diaphragmatic elevation or injury should also be noted. Finally, any fractures of the bony thorax—ribs, clavicles, and scapulae—should be sought. Alignment of the thoracic vertebrae can be appreciated on CXR, but full imaging of the spine as well as specific radiographs of the bony thoracic structures should be deferred until the patient’s airway, respiratory, and cardiovascular status has been stabilized.

Radiographic imaging is extremely useful in the diagnosis of a hemothorax or pneumothorax. Indeed, in a hemodynamically stable patient, the diagnosis is often made on the portable AP CXR obtained for the secondary survey. In the supine position the AP CXR will reveal hemothorax only when at least 200–300 ml of blood is present in the pleural space, and is suggested by an overall opacification or haziness compared to the contralateral hemithorax as the fluid will layer posteriorly (Figure 2). False “negative”–appearing CXR may occur in the setting of bilateral hemothoraces (no difference between the two sides) or when there is a simultaneous anterior pneumothorax (decreasing the relative density more similar to the other side). In the patient with penetrating chest trauma, the CXR is best taken with the patient upright which increases the sensitivity for both hemothoraces and pneumothoraces. Chest ultrasound may help to identify the presence of pleural fluid, but its sensitivity and specificity for this purpose have not been well-defined.

Figure 2 Supine chest radiograph demonstrating overall hazy appearance that is diagnostic of a right hemothorax (in this case incompletely drained by a tube thoracostomy). Note the difference between the right and left sides.

As routine truncal (chest, abdomen, and pelvis) CT scanning has become more prevalent, many patients with blunt trauma have been found to have significant anterior pneumothoraces not seen on plain CXR. The incidence of missed pneumothoraces on supine AP CXR has been estimated to be between 20%–35%. A patient with a relatively minor pneumothorax on CXR who nonetheless develops dyspnea and hypoxia may thus in fact have a significant pneumothorax that is better visualized by chest CT. In stable patients, CT scanning will reveal also pleural fluid collections and help to distinguish them from parenchymal injury such as pulmonary contusion.

The appropriate management of the patient with “CT-only” pneumothorax is a matter of some controversy (Figure 3). The reported incidence of these pneumothoraces in blunt trauma patients is 2%–8%.^10,11 The available literature suggests that 20% of these patients will require tube thoracostomy. The decision to place a chest tube, however, should be dictated by the patient’s overall status. Patients who are multiply injured, are in hemorrhagic shock, or have sustained a traumatic brain injury will not tolerate progression of even a small pneumothorax (see Figure 3). These patients would benefit from tube thoracostomy. In patients where the clinical picture appears stable, observation can be undertaken, with serial radiographs taken at 6 and 24 hours after diagnosis.

Figure 3 CT scan (A) demonstrating small bilateral “CT-only” pneumothoraces. Chest radiograph of the same patient (B), following mechanical ventilation. Note the large left pneumothorax, demonstrating the somewhat unpredictable outcome of these small pneumothoraces. The patient never developed a pneumothorax on the right. CT, Computed tomography.

Computed tomography (CT) of the chest has become increasingly accepted in the early management of trauma. CT can reveal injuries not seen on initial CXR in about two-thirds of major trauma patients¹² and can lead to therapeutic changes in 5%–30% of cases^13,14 (Figure 4). In addition, CT scanning may reveal additional findings that are only suggested by an abnormal CXR (Figure 5). There are a number of specific situations in which chest CT contributes significantly to trauma management. CT of the thoracic spine is the “gold-standard” imaging modality for assessing vertebral body as well as posterior element fractures, and is also helpful in imaging the spine at the cervicothoracic junction.^12,14,15 In patients with the nonspecific finding of a widened mediastinum on CXR, use of CT can help to limit the use of aortography to assess aortic injuries.^16–18 As CT technology improves and as further studies become available, the role of CT in chest trauma will become better-defined.

Figure 4 Chest radiograph of patient ejected from a motor vehicle at high rate of speed (A). The lung fields are essentially clear, although the mediastinal contour is abnormal. CT scan (B) of the same patient demonstrating significant pulmonary contusions, which helped explain the patient’s clinical hypoxemia. In addition, an injury to the descending aorta is also visualized. CT, Computed tomography.

Figure 5 (A) The impact of CT scanning with more obvious severe chest trauma following a motor vehicle collision. Physical examination demonstrated no paradoxical motion in the upper right hemithorax. There are multiple (seven) rib fractures, a haziness over the entire right hemithorax and subcutaneous emphysema but no obvious pneumothorax. (B) CT scan of the same patient. A chest tube was inserted based on the marked subcutaneous emphysema present on physical exam that drained no air on insertion and minimal amount of blood. The haziness turned out to be only a modest pulmonary contusion with a minimal hemothorax. The scan revealed a total of 18 distinct rib fractures with considerably more displacement than was noted on the plain radiograph. The reason for the lack of paradoxical motion is explained by the posterior nature of the flail segments. In addition, a nondisplaced scapula fracture and six thoracic transverse process fractures were identified. CT, Computed tomography.

Ultrasonography has become important in the assessment of intra-abdominal hemorrhage and pericardial fluid collections in the trauma patient. Recent reports also suggest that it might be useful to assess the pleural spaces for pneumothoraces and hemothoraces.^19–21 The pleural space is interrogated by placing the ultrasound probe between the ribs and looking for the characteristic signs of pneumothorax.^19,22