Combination of Static Echocardiographic Indices for Prediction of Fluid Responsiveness During Cardiac Surgery

In the perioperative or critical care of hemodynamically unstable patients, appropriate fluid resuscitation guided by reliable preload indices is of pivotal importance as only half of them are fluid responsive, and that empiric fluid administration actually leads to dismal prognosis. In the continuum of being non-invasive, combinations of tissue Doppler-derived parameters of early (e') and late (a') diastolic, and peak systolic velocity (s') of the mitral annulus provide information regarding the systolic dysfunction and preload (e'/s'), and LV stiffness (e'/a'). Although the left ventricular end-diastolic area (LVEDA) alone is not a valid predictor of fluid responsiveness, combining LVEDA with these indices would provide comprehensive information regarding the LV dimension, preload, and compliance as well as systolic function. Also, it seems logical to assume that patients with low LVEDA and high e' velocity indicating preserved early diastolic relaxation or low e (early mitral inflow velocity) /e' ratio indicating normal LV filling pressure would more likely be fluid responsive. Yet, these assumptions have not been tested before. Moreover, these values can be reliably obtained regardless of the heart rhythm, except for a', and do not completely rely on heart-lung interaction as opposed to the dynamic indices. Thus, the aim of this prospective trial is to investigate the role of LVEDA combined with e, e', a' or s' as a preload index in predicting fluid responsiveness in patients scheduled for off-pump coronary bypass surgery, in closed-chest conditions.