Which clinical sign involves the observation of a decrease in systolic blood pressure during inspiration?

Pulsus paradoxus is a clinical sign characterized by a notable decrease in systolic blood pressure during inspiration, typically defined as a drop of more than 10 mmHg. This phenomenon occurs due to changes in intrathoracic pressure during the respiratory cycle; when a patient inhales, the negative pressure causes increased venous return to the right side of the heart while simultaneously reducing left ventricular filling. As a consequence, the left ventricle may not pump effectively under the expanded volume, leading to a decrease in blood pressure.

Understanding pulsus paradoxus is crucial, especially in the context of conditions such as cardiac tamponade or severe asthma, where this sign can indicate significant hemodynamic changes. The other terms listed—Beck’s Triad, gallop rhythm, and normal sinus rhythm—do not pertain specifically to the decrease in systolic blood pressure during inspiration, making pulsus paradoxus the relevant and accurate choice in this scenario.