Page 49 - Clinical Pearls in Cardiology

Arterial Pulse and Blood Pressure 37

“pulsus paradoxus” is used to denote a greater than the
normal fall in blood pressure during inspiration (i.e
greater than 10 mm Hg fall). The most common cause
of pulsus paradoxus is cardiac tamponade. However,
the most severe degree of pulsus paradoxus is seen in
acute severe asthma, where the systolic blood pressure
may fall by about 40 mm Hg during inspiration (Fig. 5).

Fig. 5: Pulsus paradoxus
The degree or severity of paradox is best documented
using a sphygmomanometer cuff. In a patient with
pulsus paradoxus, as the pressure of the cuff is
reduced, initially there is a point (Point A) where the
Korotkoff’s sounds are heard intermittently, i.e. only
during expiration. With a further reduction in cuff
pressure, there is another point (Point B) where the
Korotkoff’s sounds are heard continuously with every
beat, i.e. during both inspiration and expiration. The
difference between these two points (i.e. Point A minus
Point B) gives the degree of paradox and it is recorded
in mm Hg.