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

Which type of shock is characterized by decreased blood volume?

1. Cardiogenic shock

2. Distributive shock

3. Hypovolemic shock

4. Obstructive shock

The correct answer is: Hypovolemic shock

Hypovolemic shock is characterized by a significant decrease in blood volume, which can result from a variety of causes such as severe bleeding, dehydration, or fluid loss due to conditions like burns or diarrhea. When the blood volume decreases, the heart does not have enough fluid to pump effectively, leading to a drop in blood pressure and inadequate perfusion of tissues and organs. In this type of shock, the body attempts to compensate for the low blood volume through mechanisms such as increasing heart rate and constricting blood vessels, but if the volume loss is significant and not corrected, it can lead to shock symptoms including confusion, lethargy, and even organ failure. The other types of shock involve different underlying mechanisms. For instance, cardiogenic shock is primarily due to the heart's inability to pump blood effectively, distributive shock involves abnormal distribution of blood flow often due to vasodilation (like in septic shock), and obstructive shock is caused by a physical obstruction of blood flow (like in tension pneumothorax or pulmonary embolism). Each of these has distinct causes and physiological responses, which underscores why hypovolemic shock is specifically linked to decreased blood volume.