Pulsus paradoxus is most commonly observed in which condition?

• A. Heart attack
• B. Not related to intrathoracic pressure
• C. Severe obstructive lung disease
• D. Healthy individuals

Answer: (C)

Pulsus paradoxus is the exaggerated drop in systolic blood pressure that occurs during inspiration, typically more than 10 mmHg. This happens because severe obstructive lung disease creates very negative intrathoracic pressure when you breathe in. That strong negative pressure increases venous return to the right heart and shifts the interventricular septum, which reduces left-sided filling and stroke volume during inspiration. The result is a larger-than-normal fall in systolic blood pressure with inspiration.

This sign is most commonly seen in severe obstructive lung conditions, such as asthma or COPD, where the inspiratory effort and air trapping amplify the intrathoracic pressure changes. It’s not a typical feature in healthy individuals, and while pulsus paradoxus can also occur with other conditions like cardiac tamponade, the given scenario best matches severe obstructive lung disease.