Pulsus Paradoxus: Sensitivity and Specificity
>12 mmHg. Note that pooled results from additional studies only looking at sensitivity showed a decreased sensitivity of around 82%.
The examiner inflates the sphygmomanometer cuff fully, listens for Korotkoff sounds as the cuff is slowly deflated, and then notes the pressure at which Korotkoff sounds are initially audible only during expiration. As the cuff is further deflated, the examiner notes the pressure at which Korotkoff sounds become audible during expiration and inspiration. The difference between these 2 pressures is the pulsus paradoxus. In cardiac tamponade, the pulsus paradoxus measures greater than 10 mm Hg. Inspiratory diminution in the pulse wave amplitude seen on this arterial tracing demonstrates pulsus paradoxus. A similar phenomenon may be observed on a pulse oximeter waveform.
98% sensitive, 83% specific