Paradoxical pulse/pulsus paradoxus is defined as?

Paradoxical pulse, or pulsus paradoxus, refers specifically to a variation in pulse amplitude with respiration. It is characterized by a drop in blood pressure during inspiration, causing the pulse to weaken or diminish, and then returning to normal or increasing during expiration. This phenomenon is often observed in conditions such as cardiac tamponade or severe asthma, where the changes in thoracic pressure during breathing have a significant impact on blood flow and circulation.

In this context, the correct answer identifies the variability of the pulse that occurs with changes in respiration. The other choices do not accurately describe this condition: a pulse that is consistently absent does not align with the definition of pulsus paradoxus, which describes a pulse that is present but fluctuates; a pulse that increases with inspiration incorrectly suggests the opposite of what occurs; and a rapid and irregular pulse does not encompass the definition related to respiratory variation. Thus, recognizing that pulsus paradoxus involves changes in pulse strength related to the phases of breathing is essential for understanding its clinical significance.