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Background  Assessment of cardiac preload is important for clinical management of some emergencies related to hypovolemia. Effects of acute simulated hypovolemia on Doppler blood flow velocity indices of tricuspid valve (TV) and superior vena cava (SVC) were investigated in order to find sensitive Doppler indices for predicting right ventricular preload.    Methods  Doppler flow patterns of SVC and TV in 12 healthy young men were examined by transthoracic echocardiography (TTE) during graded lower body negative pressure (LBNP) of up to -60 mm Hg which simulated acute hypovolemia. Peak velocities of all waves and their related ratios (SVC S/D and tricuspid E/A) were measured, calculated and statistically analyzed.    Results  Except for the velocity of tricuspid A wave, velocities of all waves and their related ratios declined during volume decentralization. Of all indices measured, the peak velocities of S wave and AR wave in SVC correlated most strongly with levels of LBNP (r = -0.744 and -0.771,  p  < 0.001).    Conclusion  The S and AR velocities are of good values in assessing right ventricular preload. Monitoring SVC flow may provide a relatively noninvasive means to assess direct changes in right ventricular preload.

cardiovascular ultrasound

Comparison of tricuspid inflow and superior vena caval Doppler velocities in acute simulated hypovolemia: new non-invasive indices for evaluating right ventricular preload