Does a pulsus paradoxus greater than 10 mm Hg help diagnose cardiac tamponade in patients with a pericardial effusion?
In patients with pericardial effusion, a pulsus paradoxus >10 mm Hg is a key clinical finding to help identify cardiac tamponade.
Among patients with cardiac tamponade, a minority will not have dyspnea, tachycardia, elevated jugular venous pressure, or cardiomegaly on chest radiograph. A pulsus paradoxus greater than 10 mm Hg among patients with a pericardial effusion helps distinguish those with cardiac tamponade from those without. Diagnostic certainty of the presence of tamponade requires additional testing.
Roy et al. (2007) studied this question.