In medicine, a pulsus paradoxus (PP), also paradoxic pulse and paradoxical pulse, is a sign that is indicative of several conditions including cardiac tamponade and obstructive lung diseases (e.g. asthma).Khasnis A, Lokhandwala Y. Clinical signs in medicine: pulsus paradoxus. J Postgrad Med. 2002 Jan-Mar;48(1):46-9. PMID 12082330. Full Text.

The paradox in pulsus paradoxus is that one can detect extra beats in cardiac auscultation when compared to the radial pulse. PP is quantified using a blood pressure cuff and stethoscope, by measuring the variation of the pressure in systole with respiration. Normal systolic blood pressure variation (with respiration) is considered to be 10 mmHg.

PP has been shown to be predictive of the severity of cardiac tamponade.Curtiss EI, Reddy PS, Uretsky BF, Cecchetti AA. Pulsus paradoxus: definition and relation to the severity of cardiac tamponade. Am Heart J. 1988 Feb;115(2):391-8. PMID 3341174.

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