Echocardiographic prediction of volume responsiveness in critically ill patients with spontaneously breathing activity

Objective: In hemodynamically unstable patients with spontaneous breathing activity, predicting volume responsiveness is a difficult challenge since the respiratory variation in arterial pressure cannot be used. Our objective was to test whether volume responsiveness can be predicted by the response of stroke volume measured with transthoracic echocardiography to passive leg raising in patients with spontaneous breathing activity. We also examined whether common echocardiographic indices of cardiac filling status are valuable to predict volume responsiveness in this category of patients. Design and setting: Prospective study in the medical intensive care unit of a university hospital. Patients: 24 patients with spontaneously breathing activity considered for volume expansion. Measurements: We measured the response of the echocardiographic stroke volume to passive leg raising and to saline infusion (500ml over 15min). The left ventricular end-diastolic area and the ratio of mitral inflow E wave velocity to early diastolic mitral annulus velocity (E/Ea) were also measured before and after saline infusion. Results: A passive leg raising induced increase in stroke volume of 12.5% or more predicted an increase in stroke volume of 15% or more after volume expansion with a sensitivity of 77% and a specificity of 100%. Neither left ventricular end-diastolic area nor E/Ea predicted volume responsiveness. Conclusions: In our critically ill patients with spontaneous breathing activity the response of echocardiographic stroke volume to passive leg raising was a good predictor of volume responsiveness. On the other hand, the common echocardiographic markers of cardiac filling status were not valuable for this purpose.