Fluid Responsiveness Prediction During Prone Position

Bed tilting from the +13° position to the -13° position for 60 seconds. Evaluator: relative change in continuous cardiac index between baseline, and the highest value observed during the maneuver

"End-expiratory pause performed on the ventilator, and maintained for 15 seconds.~Evaluator: relative change in continuous cardiac index between baseline, and the value observed in the last 5 seconds of the respiratory pause"

"End-inspiratory pause performed on the ventilator, and maintained for 15 seconds.~Evaluator: relative change in continuous cardiac index between baseline, and the value observed in the last 5 seconds of the respiratory pause. The evaluator is calculated as the sum of the relative change in cardiac index observed during the end-expiratory pause and that of the end-inspiratory pause. Hence, for this test, the evaluator will be coupled with that of intervention 2 (end-expiratory occlusion test)."

"Increase in tidal volume set on the ventilator from 6 ml.kg-1 of predicted body weight, to 8 ml.kg-1 for 60 seconds.~Evaluator: difference in the pulse pressure variation measured at 6 ml.kg-1 and at 8 ml.kg-1."

"After the 4 tests, the patient will receive a 500-ml fluid bolus of crystalloids in less than 15 minutes.~Evaluator (reference method): cardiac index measured by transpulmonary thermodilution before and immediately after the fluid bolus. Patients with a relative change in cardiac index \> 15% will be identified as being fluid responders, and the others as non-responders."