Which of the following is a cause of obstructive shock?

• A. Pulmonary embolism
• B. Myocardial infarction
• C. Hypovolemia
• D. Sepsis

Answer: (A)

Obstructive shock occurs when a physical blockage impedes blood flow, preventing adequate return to the heart or outflow from it, which lowers cardiac output and tissue perfusion. A massive pulmonary embolism fits this pattern by blocking the pulmonary arteries, increasing right-heart afterload, and reducing left-ventricular filling, leading to hypotension and shock even if the patient’s blood volume is normal. The other conditions produce different types of shock: myocardial infarction typically causes cardiogenic shock from pump failure; severe fluid loss causes hypovolemic shock; and sepsis causes distributive shock with widespread vasodilation and maldistribution of blood flow.