[Physical diagnosis--paradoxical pulse].

Pulsus paradoxus is generally defined as a decline in the systemic systolic blood pressure by more than 10 mmHg during inspiration. The main clinical situations in which a paradoxical pulse may be observed are inflow obstruction into the heart (as in exsudative pericarditis or cardiac tamponade) or extreme respiratory variations in intrathoracal pressure (as during an asthma attack). However, clinical studies indicate that in both situations the predictive value of a present or absent pulsus paradoxus is rather limited.