American Association of Critical-Care Nurses (AACN) Certification Practice Test

Which condition is NOT considered a cause of obstructive shock?

1. Pulmonary embolus

2. Tension pneumothorax

3. Severe burns

4. Cardiac tamponade

The correct answer is: Severe burns

Severe burns are not considered a cause of obstructive shock primarily because they typically lead to a different physiological response. In cases of severe burns, the body experiences significant fluid loss and can result in distributive shock due to vasodilation and increased vascular permeability, rather than obstruction of blood flow to the heart or major vessels. In contrast, other listed conditions such as pulmonary embolus, tension pneumothorax, and cardiac tamponade are all characterized by direct mechanical obstruction affecting the heart's ability to pump effectively or restricting blood flow returning to the heart. For instance, a pulmonary embolus blocks blood flow in the pulmonary arteries, tension pneumothorax increases pressure within the chest and compresses the heart, and cardiac tamponade results from fluid accumulation in the pericardial space which hinders the heart’s capacity to fill appropriately. These conditions disrupt circulation in ways that lead to obstructive shock, while severe burns follow a different pathophysiological route.