Why does tension pneumothorax cause hypotension?

Why does tension pneumothorax cause hypotension?

• A. Increased venous return
• B. The heart and great vessels are compressed/shifted and cardiac output is reduced
• C. Hypertension
• D. Dehydration

Answer: (B)

In tension pneumothorax, air builds up under pressure in the pleural space, raising intrathoracic pressure. This pressure compresses the heart and great vessels and can push the mediastinum to the opposite side. As a result, venous return to the heart is hindered, preload drops, stroke volume falls, and cardiac output declines, leading to hypotension. This is a form of obstructive shock caused by external pressure on the heart and vessels. Increased venous return would not cause hypotension, hypertension is not the consequence of this mechanism, and dehydration isn’t the acute driver in this scenario.

In tension pneumothorax, air builds up under pressure in the pleural space, raising intrathoracic pressure. This pressure compresses the heart and great vessels and can push the mediastinum to the opposite side. As a result, venous return to the heart is hindered, preload drops, stroke volume falls, and cardiac output declines, leading to hypotension. This is a form of obstructive shock caused by external pressure on the heart and vessels. Increased venous return would not cause hypotension, hypertension is not the consequence of this mechanism, and dehydration isn’t the acute driver in this scenario.