Why does pulsus paradoxus occur?

Pulsus paradoxus occurs due to a significant drop in blood pressure during inhalation, typically seen in conditions like cardiac tamponade, severe Asthma, or chronic obstructive pulmonary disease (COPD). During inhalation, increased intrathoracic pressure can impair venous return to the heart, leading to reduced stroke volume and subsequently lower systolic blood pressure. This phenomenon is characterized by a difference of more than 10 mmHg in blood pressure readings between inhalation and exhalation. It reflects underlying pathophysiological changes in the cardiovascular system in response to respiratory mechanics.