Laboratory Studies
Laboratory examinations are rarely required in the acute treatment of patients with penetrating chest trauma (PCT).
Hemoglobin or hematocrit values and arterial blood gas determinations offer the most useful information for treating these patients; however, tests may be temporarily delayed until patients are stabilized. Blood chemistry results, serum electrolyte values, and white blood cell (WBC) and platelet counts add little information for initial treatment but can establish a baseline by which to follow the course of the patient through his or her therapy.
Underlying medical conditions (eg, diabetes, chronic renal insufficiency), either known or discovered via the laboratory examinations, should be noted and treated when appropriate.
Imaging Studies
With improvements in modern imaging, a number of different diagnostic modalities have become available to aid in precisely defining the extent of trauma. Various groups have championed their own protocols as preeminent. In reality, any number of acceptable algorithms can help in the treatment of a patient with PCT.
As noted, the history and physical examination are usually brief and oriented to the injury. If the patient is stable and no significant injury is found that necessitates immediate surgery, a full diagnostic evaluation can be performed.
Chest radiography remains the basis for initiating other investigations.
Computed tomography (CT) is rapidly evolving into a primary diagnostic tool because of its ability to image various intrathoracic structures and to differentiate substances of different densities (eg, solid vs air-containing fluid collections). The advent of multidetector CT (MDCT) in clinical practice has dramatically increased the speed of data acquisition and image reconstruction, and many reports emphasizing this change in imaging approach have been published. [11]
Delayed radiographs have been the standard of care for stable patients with PCT. Initial chest CT obviates the need for repeat chest radiography after PCT. [12]
Aortography, once considered the criterion standard for determining vascular injuries, has gradually fallen out of favor and been largely supplanted by faster, less invasive, and better-tolerated imaging techniques. The revival of aortography with endovascular intervention for trauma to the thoracic aorta or branches of the aortic arch (innominate, carotid, and subclavian arteries) is largely a product of modern technology. Endovascular stent graft arterial repair has altered the approach to vascular trauma. [13]
Penetrating injuries traversing the mediastinum or in proximity to posterior mediastinal structures dictate esophageal and tracheal evaluation, preferably via direct visualization (eg, esophagoscopy or bronchoscopy).
Specialized windows for ultrasonography (US) have been developed to allow imaging of some intrathoracic structures despite the presence of lung air. With the focused sssessment with sonography for trauma (FAST) protocols, evaluation of the thorax and the abdomen can be completed within minutes.
Readily available in most centers, echocardiography has developed to the point where it is indispensable in helping evaluate injuries to the heart and the ascending and descending aortas. Studies have demonstrated that echocardiography can also be used to detect hemothoraces and pneumothoraces with accuracy. [14]
In appropriate settings, close observation (without thoracotomy) may be considered. However, the limitations of each of the above-noted diagnostic modalities must be remembered, and these modalities must not be extended beyond their functional limits, especially if patient safety is compromised.
Other Tests
Because most trauma patients are young, extensive cardiac evaluations are often unnecessary. Admission electrocardiography (ECG) can be deferred until the patient is stable, unless cardiac injury is considered likely. Frequently, however, immediacy of resuscitation and definitive treatment preclude obtaining ECGs. In elderly patients, ECG evidence of prior myocardial infarctions may assist in the management of dysrhythmias or potential cardiac failure.
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Upright posteroanterior chest radiograph of patient with right-side hemothorax.
