How is pulsus paradoxus identified in the evaluation of acute pericarditis?

Updated: Apr 02, 2019
  • Author: Sean Spangler, MD; Chief Editor: Terrence X O'Brien, MD, MS, FACC  more...
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Pulsus paradoxus occurs in 70-80% of patients with pericardial tamponade and is measured by careful auscultation with a blood pressure cuff. The first sphygmomanometer reading is recorded at the point when the beats are audible during expiration and disappear with inspiration. The second reading is taken when each beat is audible during the entire respiratory cycle (ie, both inspiration and expiration).

A difference of more than 10 mm Hg defines pulsus paradoxus. This decrease is important in patients with more slowly developing tamponade, because they may lack findings of the Beck triad. If an associated hemorrhage is outside the pericardial sac, hypotension and tachycardia without elevated jugular venous distension may be found.

Pulsus paradoxus also occurs in patients with severe asthma, constrictive pericarditis, and severe congestive heart failure. See the image below.

Recording of aortic pressure showing pulsus parado Recording of aortic pressure showing pulsus paradoxus. During inspiration, systolic pressure declines 20 mm Hg. Courtesy of Zhi Zhou, MD.

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