Fig. 4From: Rationale for using the velocity–time integral and the minute distance for assessing the stroke volume and cardiac output in point-of-care settingsLeft ventricular tract velocity–time integral (LVOT VTI, yellow boxes) for assessing changes in the SV with treatments, in a patient with suspicion of hypovolemia. a Baseline. b After a fluid challenge. A > 15% increase in the VTI indicates a positive response to therapy, as seen in this caseBack to article page