Blunt Chest Trauma Workup

Updated: Jul 07, 2016
  • Author: Mary C Mancini, MD, PhD, MMM; Chief Editor: John Geibel, MD, DSc, MSc, AGAF  more...
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Workup

Approach Considerations

Initial emergency workup of a patient with multiple injuries should begin with the ABCs (airway, breathing, and circulation), with appropriate intervention taken for each step. Subsequent steps in the workup (see below) may include laboratory studies, radiography, computed tomography (CT), ultrasonography, endoscopy, and electrocardiography (ECG).

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Laboratory Studies

A complete blood count (CBC) is a routine laboratory test for most trauma patients. The CBC helps gauge blood loss, though it is not entirely reliable for accurately determining acute blood loss. Other important information provided includes platelet and white blood cell (WBC) counts, with or without differential.

Arterial blood gas (ABG) analysis, though not as important in the initial assessment of trauma victims, is important in their subsequent management. ABG determinations are an objective measure of ventilation, oxygenation, and acid-base status, and their results help guide therapeutic decisions such as the need for endotracheal intubation and subsequent extubation.

Patients who are seriously injured and require fluid resuscitation should have periodic monitoring of their electrolyte status. This can help avoid problems such as hyponatremia or hypernatremia. The etiology of certain acid-base abnormalities can also be identified, eg, a chloride-responsive metabolic alkalosis or hyperchloremic metabolic acidosis.

The coagulation profile, including prothrombin time (PT)/activated partial thromboplastin time (aPTT), fibrinogen, fibrin degradation product, and D-dimer analyses, can be helpful in the management of patients who receive massive transfusions (eg, >10 units of packed red blood cells [RBCs]). Patients who manifest hemorrhage that cannot be explained by surgical causes should also have their profile monitored.

Whereas elevated serum troponin I levels correlate with the presence of echocardiographic or ECG abnormalities in patients with significant blunt cardiac injuries, these levels have low sensitivity and predictive values in diagnosing myocardial contusion in those without such injuries. Accordingly, troponin I level determination does not, by itself, help predict the occurrence of complications that may require admission to the hospital. Accordingly, its routine use in this clinical situation is not well supported. [2, 3]

Measurement of serum myocardial muscle creatine kinase isoenzyme (creatine kinase-MB) levels is frequently performed in patients with possible blunt myocardial injuries. The test is rapid and inexpensive. This diagnostic modality has been criticized because of poor sensitivity, specificity, and positive predictive value in relation to clinically significant blunt myocardial injuries.

Lactate is an end product of anaerobic glycolysis and, as such, can be used as a measure of tissue perfusion. Well-perfused tissues mainly use aerobic glycolytic pathways. Persistently elevated lactate levels have been associated with poorer outcomes. Patients whose initial lactate levels are high but are rapidly cleared to normal have been resuscitated well and have better outcomes.

Type and crossmatch are among the most important blood tests in the evaluation and management of a seriously injured trauma patient, especially one who is predicted to require major operative intervention.

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Plain and Contrast Radiography

Chest radiography

The chest x-ray (CXR) is the initial radiographic study of choice in patients with thoracic blunt trauma. A chest radiograph is an important adjunct in the diagnosis of many conditions, including chest-wall fractures, pneumothorax, hemothorax, and injuries to the heart and great vessels (eg, enlarged cardiac silhouette, widened mediastinum).

In contrast, certain cases arise in which physicians should not wait for a chest radiograph to confirm clinical suspicion. The classic example is a patient presenting with decreased breath sounds, a hyperresonant hemithorax, and signs of hemodynamic compromise (ie, tension pneumothorax). This scenario warrants immediate decompression before a chest radiograph is obtained. [4]

A 2012 study by Paydar et al indicated that routine chest radiography in stable blunt trauma patients may be of low clinical value. The authors proposed that careful physical examination and history taking can accurately identify those patients at low risk for chest injury, thus making routine radiographs unnecessary. [5]

Aortography

Aortography has been the criterion standard for diagnosing traumatic thoracic aortic injuries. However, its limited availability and the logistics of moving a relatively critical patient to a remote location make it less desirable. In addition, the introduction of spiral CT scanners, which have 100% sensitivity and greater than 99% specificity, has caused the role of aortography in the evaluation of trauma patients to decline.

However, where spiral CT is equivocal, aortography can provide a more exact delineation of the location and extent of aortic injuries. Aortography is much better at demonstrating injuries of the ascending aorta. In addition, it is superior for imaging injuries of the thoracic great vessels. [6, 7]

Contrast esophagography

Contrast esophagograms are indicated for patients with possible esophageal injuries in whom esophagoscopy results (see Endoscopy) are negative. Esophagography is first performed with water-soluble contrast media. If this provides a negative result, a barium esophagogram is obtained. If these results are also negative, esophageal injury is reliably excluded.

Esophagoscopy and esophagography are each approximately 80-90% sensitive for esophageal injuries. These studies are complementary and, when performed in sequence, identify nearly 100% of esophageal injuries.

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Computed Tomography

Because of the relative insensitivity of chest radiography for identifying significant injuries, CT of the chest is frequently performed in the trauma bay in the hemodynamically stable patient. In one study, 50% of patients with normal chest radiographs were found to have multiple injuries on chest CT. As a result, obtaining a chest CT scan in a supposedly stable patient with significant mechanism of injury is becoming routine practice.

Spiral (helical) CT and CT angiography (CTA) are being used more commonly in the diagnosis of patients with possible blunt aortic injuries. Most authors recommend that positive findings or findings suggestive of an aortic injury (eg, mediastinal hematoma) be augmented by aortography for more precise definition of the location and extent of the injury. [8, 9, 10]

In a study by Akoglu et al, abdominal CT alone or combined with cervical spinal CT detected almost all occult small pneumothoraces in one study of patients with blunt trauma, whereas cervical spinal CT alone detected only one third of cases. [11]

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Ultrasonography

Thoracic ultrasonography

Ultrasound examinations of the pericardium, heart, and thoracic cavities can be expeditiously performed by surgeons and emergency department (ED) physicians within the ED. Pericardial effusions or tamponade can be reliably recognized, as can hemothoraces associated with trauma. The sensitivity, specificity, and overall accuracy of ultrasonography in these settings are all greater than 90%.

Focused assessment with sonography for trauma

The focused assessment with sonography for trauma (FAST) is routinely conducted in many trauma centers. Although this examination mainly deals with abdominal trauma, the first step is to obtain an image of the heart and pericardium to assess for evidence of intrapericardial bleeding.

Echocardiography

Transesophageal echocardiography (TEE) has been extensively studied for use in the workup of possible blunt rupture of the thoracic aorta. Its sensitivity, specificity, and accuracy in the diagnosis of this injury are each approximately 93-96%.

The advantages of TEE include the easy portability, the absence of a need for contrast material, the minimal invasiveness, and the short time required to perform it. TEE can also be used intraoperatively to help identify cardiac abnormalities and monitor cardiac function. [12, 13, 14]  The disadvantages include the requirement for operator expertise, the long learning curve, and the relative weakness of the modality for helping identify injuries to the descending aorta.

Transthoracic echocardiography (TTE) can help identify pericardial effusions and tamponade, valvular abnormalities, and disturbances in cardiac wall motion. TTE is also performed in cases where patients have possible blunt myocardial injuries and abnormal ECG findings.

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Endoscopy

Esophagoscopy

Esophagoscopy is the initial diagnostic procedure of choice in patients with possible esophageal injuries. Either flexible or rigid esophagoscopy is appropriate, and the choice depends on the experience of the clinician. Some authors prefer rigid esophagoscopy to evaluate the cervical esophagus and flexible esophagoscopy for possible injuries of the thoracic and abdominal esophagus. If esophagoscopy findings are negative, esophagography should be performed as outlined above.

Bronchoscopy

Fiberoptic or rigid bronchoscopy is performed in patients with possible tracheobronchial injuries. Both techniques are extremely sensitive for the diagnosis of these injuries. Fiberoptic bronchoscopy offers the advantage of allowing an endotracheal tube to be loaded onto the scope and the endotracheal intubation to be performed under direct visualization if necessary.

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Electrocardiography

The 12-lead ECG is a standard test performed on all thoracic trauma victims. ECG findings can help identify new cardiac abnormalities and help discover underlying problems that may impact treatment decisions. Furthermore, it is the most important discriminator to help identify patients with clinically significant blunt cardiac injuries.

Patients with possible blunt cardiac injuries and normal ECG findings require no further treatment or investigation for this injury. The most common ECG abnormalities found in patients with blunt cardiac injuries are tachyarrhythmias and conduction disturbances, such as first-degree heart block and bundle-branch blocks.

However, according to a 2012 practice management guideline from the Eastern Association for the Surgery of Trauma (see Guidelines), ECG alone should not be considered sufficient for ruling out blunt cardiac injury. The guideline recommends obtaining an admission ECG and troponin I from all patients in whom blunt cardiac injury is suspected and states that such injury can be ruled out only if both the ECG and the troponin I level are normal. [15]

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