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Overview :
In classic pulsus paradoxicus the radial pulse is
nonpalpable yet heart sounds are heard on auscultation. Normally the systolic
blood pressure drops slightly during inspiration. Under certain circumstances
this drop may be increased.
Pulsus paradoxicus requires both of the following:
(1) drop in systolic blood pressure >= 10 mm Hg that
(2) occurs during the inspiratory phase while breathing
normally
systolic pressure difference in mm Hg =
= (systolic pressure during expiration) - (systolic pressure
during inspiration)
There is a concomitant decrease in stroke volume and cardiac
output.
Causes of pulsus paradoxicus:
(1) massive pulmonary embolism
(2) extreme hypotension, including hemorrhagic shock
(3) severe asthma or severe emphysema with hyperinflated
lungs
(4) cardiac tamponade
(5) constrictive pericarditis
(6) morbid obesity
Conditions which may cause a patient with cardiac tamponade
not to show pulsus:
(1) extreme
hypotension (including severe tamponade)
(2) acute left
ventricular myocardial infarction
(3) pericardial
adhesions
(4) right ventricular
hypertrophy without pulmonary hypertension
(5) severe
aortic regurgitation
(6) atrial
septal defect
(7)
low-pressure tamponade
(8) left
ventricular stiffness, left ventricular diastolic pressure, and pulmonary
venous diastolic pressure much greater than pressure in the right ventricle
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