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.