A 37-year-old female presents with increased work of breathing after blunt chest trauma.

Pericardial tamponade is a life-threatening condition often associated with blunt or penetrating chest trauma. NREMT instruction highlights that tamponade occurs when blood accumulates in the pericardial sac, compressing the heart and impairing cardiac output.

Option D is correct because patients with pericardial tamponade often present with increased work of breathing, hypoxia, and clear lung sounds, as the problem is cardiac rather than pulmonary. Decreasing oxygen saturation results from reduced cardiac output and poor tissue perfusion.

Option B is incorrect because tension pneumothorax typically presents with absent or diminished lung sounds on one side.

Option C usually produces crackles or signs of lung injury rather than clear lung sounds.

Option A is rare and usually associated with severe vomiting or penetrating trauma.

Early recognition of tamponade and rapid transport are critical per NREMT trauma care priorities.