What does "pulsus paradoxus" indicate?

Pulsus paradoxus is a clinical phenomenon characterized by a significant drop in blood pressure during inhalation. During normal respiration, there may be slight variations in blood pressure with respiration, but in pulsus paradoxus, this drop exceeds what is considered normal and is often more than 10 mmHg.

This condition is typically associated with various clinical scenarios, such as cardiac tamponade, severe asthma, or COPD exacerbations. The mechanism behind this phenomenon is related to the increased negative intrathoracic pressure that occurs during inhalation, which can lead to decreased venous return to the heart and subsequently reduce cardiac output. Hence, identifying pulsus paradoxus is crucial in assessing conditions where fluid accumulation around the heart or severe respiratory compromise could be present.