Which of the following injuries would MOST likely cause obstructive shock?

• A. Simple pneumothorax
• B. Spinal cord injury
• C. Liver laceration
• D. Cardiac tamponade

Answer: (D)

Obstructive shock happens when something physically blocks blood flow through the heart or great vessels, so the heart can’t fill properly or eject effectively, leading to a drop in cardiac output. Cardiac tamponade fits this mechanism because blood or fluid accumulating in the pericardial sac raises pressure around the heart and prevents it from filling, causing a sudden and severe drop in output. Among the injuries listed, tamponade is the one that directly creates that filling obstruction.

A simple pneumothorax won’t typically block venous return to the heart; a tension pneumothorax could cause obstructive effects, but the option here specifies a simple pneumothorax, which generally doesn’t produce the pressure needed to compress the heart. A spinal cord injury tends to cause neurogenic shock, with widespread vasodilation and hypotension rather than an obstruction to blood flow. A liver laceration leads to hemorrhagic (hypovolemic) shock from blood loss, not a mechanical obstruction to circulation.

So, the injury most likely to cause obstructive shock is cardiac tamponade.