Obstructive shock in trauma patients is most likely caused by which condition?

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

Answer: (A)

Obstructive shock occurs when a physical barrier prevents the heart from filling or pumping effectively, so cardiac output drops even if there is enough blood in the vessels. In trauma, cardiac tamponade is the classic cause because blood leaking into the pericardial sac builds up pressure around the heart, restricting diastolic filling. With reduced filling, the stroke volume and cardiac output fall, leading to shock that is due to obstruction of the heart’s ability to fill.

Liver laceration leads to loss of blood volume (hypovolemic shock) rather than an obstruction to filling. A simple pneumothorax mainly impairs ventilation rather than creating a true obstruction to cardiac filling; obstructive shock is more associated with tension pneumothorax, which is not the same as a simple pneumothorax. Spinal cord injury causes neurogenic shock from loss of vascular tone, not an obstruction to heart filling.