Esophageal Doppler monitoring predicts fluid responsiveness in critically ill ventilated patients

Objective To test whether fluid responsiveness can be predicted by the respiratory variation in aortic blood flow and/or the flow time corrected for heart rate monitored with esophageal Doppler.Design and setting Prospective study in a 24-bed medical intensive care unit of a university hospital.Patients 38 mechanically ventilated patients with sinus rhythm and without spontaneous breathing activity in whom volume expansion was planned.Interventions The aortic blood flow was measured using an esophageal Doppler monitoring device before and after fluid infusion (500 ml NaCl 0.9% over 10 min). The variation in aortic blood flow over a respiratory cycle between its minimal and maximal values was calculated. The flow time was also measured.Measurements and results Aortic blood flow increased by at least 15% after volume expansion in 20 patients (defined as responders). Before fluid infusion the respiratory variation in aortic flow was higher in responders than in nonresponders (28±12% vs. 12±5%). It significantly decreased after volume expansion (18±11%) in responders only. A respiratory variation in aortic flow before volume expansion of at least 18% predicted fluid responsiveness with a sensitivity of 90% and a specificity of 94%. Flow time increased with fluid infusion in responders and nonresponders. A flow time corrected for heart rate below 277 ms predicted fluid responsiveness with a sensitivity of 55% and a specificity of 94%. The area under the ROC curve generated for variation in aortic blood flow ABF was greater than that generated for flow time.Conclusions The respiratory variation in aortic blood flow reliably predicts fluid responsiveness in patients with sinus rhythm and without breathing activity.