Correct Answer:

Findings on physical examination are neither sensitive nor specific for this injury; the diagnosis depends on ancillary studies.

Educational Objective:

Recognize that aortic rupture may not present with obvious clinical signs.

Key Point:

More often than not, alive, awake patients with aortic rupture from blunt trauma will have hypertension (not hypotension) or present with nonspecific findings on physical examination.

Explanation:

The radiographic findings shown in the Figure are the classic findings of traumatic aortic rupture or disruption, ie, widened mediastinum with an obscured aortic knob. Despite the severe nature of the injury, the clinical manifestations of aortic rupture in awake patients are often deceptively meager. Typically, the physical examination is neither sensitive nor specific for aortic injury, thereby creating a dependence on ancillary testing to pursue the diagnosis.

Interestingly, traumatic aortic rupture presents somewhat commonly with hypertension (very counterintuitive, leading to missed diagnoses); in fact, hypertension has been known to occur in more than 70% of awake patients. This is thought to be due to sympathetic afferent nerve fibers, located in the area of the aortic isthmus, that are capable of causing reflex hypertension as a response to a stretching stimulus. Generalized hypertension, when present in a trauma patient, is an important clinical sign of possible blunt aortic rupture.

Other signs occur less frequently. Up to 50% of patients have no external signs of chest trauma. The classic symptom of nontraumatic aortic rupture–interscapular or retrosternal pain–is found in only 25% of patients with blunt traumatic aortic rupture. Upper extremity hypertension, along with absent or diminished femoral pulses (pseudocoarctation syndrome), has been reported to occur in one-third of these patients. Equally commonly (one-third of patients) is a harsh systolic murmur heard over the precordium or posterior interscapular area.

References:

Raja A. Thoracic trauma (chapter 38). In: Walls R, et al. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed., 2018:382-403.e2.