What is an important physical exam finding in a patient with pericardial effusion?

In the context of pericardial effusion, pulsus paradoxus is a key physical examination finding. This phenomenon refers to an exaggerated drop in systolic blood pressure during inspiration—typically more than 10 mm Hg. It occurs because the presence of fluid in the pericardial space restricts the heart's ability to fill properly during diastole, especially under the influence of inspiratory negative pressure, leading to decreased cardiac output and blood pressure during inspiration.

Patients with significant pericardial effusion may demonstrate this finding, particularly if the effusion is large or has progressed to cardiac tamponade, where it becomes more pronounced. Therefore, recognizing pulsus paradoxus is critical in assessing the hemodynamic consequences of pericardial effusion.