Beck's triad for pericardial tamponade (hypotension, distended neck veins, and, rarely, distant or muffled heart tones) is sometimes difficult to demonstrate clinically, especially in the midst of a major resuscitation with concomitant hypovolemia. The most reliable signs of pericardial tamponade are a central venous pressure (CVP) elevated to 15 cm H2O or higher associated with hypotension and tachycardia. Pulsus paradoxus may also be present. As with any patient in shock, the physical findings can include dyspnea, agitation, restlessness, cyanosis, tachycardia, hypotension, and decreasing mental activity. The cardinal signs of tension pneumothorax are tachycardia, jugular venous distention, and absent breath sounds on the ipsilateral side. These patients can also be dyspneic, agitated, restless, cyanotic, tachycardic, hypotensive, and confused. Absent breath sounds are the key to clinically differentiating these two conditions.