The goal of this study is to assess the predictive capacity of pulse pressure to estimate stroke volume, as assessed by bedside echocardiography in critically ill patients. We hypothesize that pulse pressure will be able to adequately detect low values of stroke volume, and to track changes of stroke volume during commonly used dynamic cardiovascular interventions. Pulse pressure transduced from an arterial line will be measured simultaneously with left ventricular outflow tract velocity time integral in a broad range of critically ill patients. Ancillary clinical, hemodynamic and echocardiographic data will also be registered.