Value of Pulse Pressure Variations and Corrected Flow Time in Esophageal Doppler as a Predictor of Fluid Responsiveness in Prone Position During Spinal Surgery

In patients under mechanical ventilation, Usefulness of dynamic indices based on the heart-lung interactions for guiding volume resuscitation has been well validated. Recently, validity of pulse pressure variation (PPV) has been also reported to predict fluid responsiveness. Oesophageal Doppler (OED) allows continuous monitoring of several important hemodynamic variables. Of the OED variables, corrected flow time (FTc) has been evaluated and used as a preload index, and has been reported to predict fluid responsiveness. Prone position caused physiologic and hemodynamic changes and influenced the predictability and cut-off values of SVV and PPV for fluid responsiveness. In this prospective controlled study, the investigators evaluated the validity of PPV and FTc as predictors for fluid responsiveness in supine and prone position in patients undergoing posterior lumbar spinal fusion