A 10-second fluid challenge guided by transthoracic echocardiography can predict fluid responsiveness

Introduction: The accurate assessment of intravascular volume status for the therapy of severe hypovolemia and shock is difficult and critical to critically ill patients. Non-invasive evaluation of fluid responsiveness by the rapid infusion of a very limited amount of volume is an important clinical goal. This study aimed to test whether echocardiographic parameters could predict fluid responsiveness in critically ill patients following a low-volume (50-ml crystalloid solution) infusion over 10 seconds. Methods: We prospectively studied 55 mechanically ventilated patients. Echocardiography was performed during a 50-ml infusion of crystalloid solution over 10 seconds and a further 450 ml over 15 minutes. Cardiac output (CO), stroke volume (SV), aortic velocity time index (VTI), and left ventricular ejection fraction (LVEF) were recorded. Patients were classified as responders (Rs) if CO increased by at least 15% following the 500-ml volume expansion or were classified as non-responders (NRs) if CO increased by less than 15%. Area under the receiver operating characteristic curves (AUC) compared CO variations after 50 ml over 10 seconds (Delta CO50) and 500 ml over 15 minutes (Delta CO500) and the variation of VTI after infusion of 50 ml of fluid over 10 seconds (Delta VTI50). Results: In total, 50 patients were enrolled, and 27 (54%) of them were Rs. General characteristics, LVEF, heart rate, and central venous pressure were similar between Rs and NRs. In the Rs group, the AUC for Delta CO50 was 0.95 +/- 0.03 (P < 0.01; best cutoff value, 6%; sensitivity, 93%; specificity, 91%). Moreover, Delta CO50 and Delta CO500 were strongly correlated (r = 0.87; P < 0.01). The AUC for Delta VTI50 was 0.91 +/- 0.04 (P < 0.01; best cutoff value, 9%; sensitivity, 74%; specificity, 95%). Delta VTI50 and Delta CO500 were positively correlated (r = 0.72; P < 0.01). Conclusion: In critically ill patients, the variation of CO and VTI after the administration of 50-ml crystalloid solution over 10 seconds (Delta CO50 and Delta VTI50) can accurately predict fluid responsiveness.