Stroke volume variations

During the cyclic changes in intrathoracic pressure, changes in stroke volume characterize the state at which both ventricles are preload dependant. Determining stoke volume variations may thus help to predict fluid responsiveness in mechanically ventilated patients. Selected review of the articles having investigated the stroke volume variations in critically ill patients. Stroke volume variations can effectively predict preload dependency in mechanically ventilated patients. Stroke volume can either be measured directly or estimated using the analysis of the arterial pressure waveform. Alternatively, pulse pressure variations can be calculated. However, these index are sensitive to tidal volume. During mechanical ventilation with low tidal volumes, the ventilatory-induced changes in preload may be too small to generate changes in stroke volume, even in preload dependant patients. Stroke volume variations can be useful to detect fluid responsiveness in mechanically ventilated patients.