Objective: The purpose of this study was to compare the sensitivity, specificity and positive predictive value of the respiratory changes in the transvalvular flow velocities to those of right atrial collapse and right ventricular collapse in the diagnosis of cardiac tamponade. Methods: Standard twodimensional and Doppler echocardiography were performed in 41 consecutive patients with mild to severe pericardial effusion (13 patients met the clinical criteria for cardiac tamponade, 28 patients were found to have no tamponade). Results: The sensitivity, specificity value were, respectively, 100 percent and 100 percent for an inspiratory decrease
::25 percent in the peak velocity of the early mitral flow. Right atrial collapse and right ventricular collapse had a sensitivity of 100 and 100 percent, a specificity of 85.7 percent and 100 percent, respectively. Conclusions: In the diagnosis of cardiac tamponade:1) right atrial collapse is the most sensitive sign but lacks specificity
2) the respiratory variations in the transmitralval flow velocities' have a reliability and a predictive value comparable with those of right ventricular collapse.