An unrestrained victim of a high-speed motor vehicle crash presents with a sternal bruise, pale and anxious. Vital signs: BP in the right arm 120/80, left arm 110/72; pulse 120; respirations 20; SpO2 96%. Neck veins are flat; breath sounds clear and equal; heart tones normal; abdomen soft. Femoral and pedal pulses diminished. Which injury should the paramedic suspect?

• A. Cardiac tamponade
• B. Thoracic aortic disruption
• C. Massive hemothorax
• D. Blunt cardiac injury

Answer: (B)

In deceleration injuries from a high-speed crash, a tear of the thoracic aorta is a key concern when distal perfusion is compromised but upper-chest findings are not dramatic. The scenario shows tachycardia and pallor with flat neck veins (no signs of tamponade), lungs with clear and equal breath sounds (no pneumothorax or massive hemothorax), yet diminished pulses in the femoral and pedal arteries. This pattern points to reduced blood flow to the lower body from a proximal aortic injury, typically at the aortic isthmus, which is a common site for blunt traumatic disruption in unrestrained occupants. The mechanism (high-speed impact) and the presence of distal pulse deficits without overt chest or lung signs fit thoracic aortic disruption best.

Cardiac tamponade would usually present with elevated neck venous pressure, muffled heart sounds, and hypotension. A massive hemothorax would produce absent/decreased breath sounds on one side and dullness to percussion. A blunt cardiac injury might cause chest pain, arrhythmias, or abnormal heart sounds, which aren’t indicated here.